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Title: A Treatise on Anatomy, Physiology, and Hygiene (Revised Edition)
Author: Cutter, Calvin, 1807-1872
Language: English
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Copyright Status: Not copyrighted in the United States. If you live elsewhere check the laws of your country before downloading this ebook. See comments about copyright issues at end of book.

*** Start of this Doctrine Publishing Corporation Digital Book "A Treatise on Anatomy, Physiology, and Hygiene (Revised Edition)" ***

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                    A
                 TREATISE
                    ON
           ANATOMY, PHYSIOLOGY,
               AND HYGIENE

               DESIGNED FOR
    COLLEGES, ACADEMIES, AND FAMILIES.

          BY CALVIN CUTTER, M.D.

                  -----
  WITH ONE HUNDRED AND FIFTY ENGRAVINGS.
                  -----

       REVISED STEREOTYPE EDITION.

                NEW YORK:
         CLARK, AUSTIN AND SMITH.
      CINCINNATI:--W. B. SMITH & CO.
     ST. LOUIS, MO.:--KEITH & WOODS.

                  1858.



  Entered according to Act of Congress, in the year 1852, by

  CALVIN CUTTER, M. D.,

  In the Clerk's Office of the District Court of the District
  of Massachusetts.

  C. A. ALVORD, Printer,
  No. 15 Vandewater Street, N. Y.



PREFACE.


Agesilaus, king of Sparta, when asked what things boys should learn,
replied, "Those which they will _practise_ when they become men." As
health requires the observance of the laws inherent to the different
organs of the human system, so not only boys, but girls, should
acquire a knowledge of the laws of their organization. If sound
morality depends upon the inculcation of correct principles in youth,
equally so does a sound physical system depend on a correct physical
education during the same period of life. If the teacher and parents
who are deficient in moral feelings and sentiments, are unfit to
communicate to children and youth those high moral principles demanded
by the nature of man, so are they equally incompetent directors of the
physical training of the youthful system, if ignorant of the organic
laws and the physiological conditions upon which health and disease
depend.

For these reasons, the study of the structure of the human system, and
the laws of the different organs, are subjects of interest to
all,--the young and the old, the learned and the unlearned, the rich
and the poor. Every scholar, and particularly every young miss, after
acquiring a knowledge of the primary branches,--as spelling, reading,
writing, and arithmetic,--should learn the structure of the human
system, and the conditions upon which health and disease depend, as
this knowledge will be required in _practice_ in after life.

"It is somewhat unaccountable," says Dr. Dick, "and not a little
inconsistent, that while we direct the young to look abroad over the
surface of the earth, and survey its mountains, rivers, seas, and
continents, and guide their views to the regions of the firmament,
where they may contemplate the moons of Jupiter, the rings of Saturn,
and thousands of luminaries placed at immeasurable distances, ... that
we should never teach them _to look into themselves_; to consider
their own corporeal structures, the numerous parts of which they are
composed, the admirable functions they perform, the wisdom and
goodness displayed in their mechanism, and the lessons of practical
instruction which may be derived from such contemplations."

Again he says, "One great practical end which should always be kept in
view in the study of physiology, is the invigoration and improvement
of the corporeal powers and functions, the preservation of health, and
the prevention of disease."

The design of the following pages is, to diffuse in the community,
especially among the youth, a knowledge of Human Anatomy, Physiology,
and Hygiene. To make the work clear and practical, the following
method has been adopted:--

1st. The structure of the different organs of the system has been
described in a clear and concise manner. To render this description
more intelligible, one hundred and fifty engravings have been
introduced, to show the situation of the various organs. Hence the
work may be regarded as an elementary treatise on anatomy.

2d. The functions, or uses of the several parts have been briefly and
plainly detailed; making a primary treatise on human physiology.

3d. To make a knowledge of the structure and functions of the
different organs _practical_, the laws of the several parts, and the
conditions on which health depends, have been clearly and succinctly
explained. Hence it may be called a treatise on the principles of
hygiene, or health.

To render this department more complete, there has been added the
appropriate treatment for burns, wounds, hemorrhage from divided
arteries, the management of persons asphyxiated from drowning,
carbonic acid, or strangling, directions for nurses, watchers, and the
removal of disease, together with an Appendix, containing antidotes
for poisons, so that persons may know what _should be done_, and what
_should not be done_, until a surgeon or physician can be called.

In attempting to effect this in a brief elementary treatise designed
for schools and families, it has not been deemed necessary to use
vulgar phrases for the purpose of being understood. The appropriate
scientific term should be applied to each organ. No more effort is
required to learn the meaning of a _proper_, than an improper term.
For example: a child will pronounce the word as readily, and obtain as
correct an idea, if you say _lungs_, as if you used the word _lights_.
A little effort on the part of teachers and parents, would diminish
the number of vulgar terms and phrases, and, consequently, improve the
language of our country. To obviate all objections to the use of
proper scientific terms, a Glossary has been appended to the work.

The author makes no pretensions to new discoveries in physiological
science. In preparing the anatomical department, the able treatises of
Wilson, Cruveilhier, and others have been freely consulted. In the
physiological part, the splendid works of Carpenter, Dunglison,
Liebig, and others have been perused. In the department of hygiene
many valuable hints have been obtained from the meritorious works of
Combe, Rivers, and others.

We are under obligations to R. D. Mussey, M. D., formerly Professor of
Anatomy and Surgery, Dartmouth College, N. H., now Professor of
Surgery in the Ohio Medical College; to J. E. M'Girr, A. M., M. D.,
Professor of Anatomy, Physiology, and Chemistry, St. Mary's
University, Ill.; to E. Hitchcock, Jr., A. M., M. D., Teacher of
Chemistry and Natural History, Williston Seminary, Mass.; to Rev. E.
Hitchcock, D. D., President of Amherst College, Mass., who examined
the revised edition of this work, and whose valuable suggestions
rendered important aid in preparing the manuscript for the present
stereotype edition.

We return our acknowledgments for the aid afforded by the Principals
of the several Academies and Normal Schools who formed classes in
their institutions, and examined the revised edition as their pupils
progressed, thus giving the work the best possible test trial, namely,
the recitation-room.

To the examination of an intelligent public, the work is respectfully
submitted by

                                                        CALVIN CUTTER.

WARREN, MASS., _Sept. 1, 1852_.



TO TEACHERS AND PARENTS.


As the work is divided into chapters, the subjects of which are
complete in themselves, the pupil may commence the study of the
structure, use, and laws of the several parts of which the human
system is composed, by selecting such chapters as fancy or utility may
dictate, without reference to their present arrangement,--as well
commence with the chapter on the digestive organs as on the bones.

The acquisition of a correct pronunciation of the technical words is
of great importance, both in recitation and in conversation. In this
work, the technical words interspersed with the text, have been
divided into syllables, and the accented syllables designated. An
ample Glossary of technical terms has also been appended to the work,
to which reference should be made.

It is recommended that the subject be examined in the form of
_topics_. The questions in _Italics_ are designed for this method of
recitation. The teacher may call on a pupil of the class to describe
the anatomy of an organ from an anatomical outline plate; afterwards
call upon another to give the physiology of the part, while a third
may state the hygiene, after which, the questions at the bottom of
the page may be asked promiscuously, and thus the detailed knowledge
of the subject possessed by the pupils will be tested.

At the close of the chapters upon the Hygiene of the several portions
of the system, it is advised that the instructor give a lecture
reviewing the anatomy, physiology, and hygiene, of the topic last
considered. This may be followed by a general examination of the class
upon the same subject. By this course a clear and definite knowledge
of the mutual relation of the Anatomy, Physiology, and Hygiene, of
different parts of the human body, will be presented.

We also suggest the utility of the pupils' giving analogous
illustrations, examples, and observations, where these are interspersed
in the different chapters, not only to induce inventive thought, but to
discipline the mind.

To parents and others we beg leave to say, that about two thirds of
the present work is devoted to a concise and practical description of
the uses of the important organs of the human body, and to show how
such information may be usefully applied, both in the preservation of
health, and the improvement of physical education. To this have been
added directions for the treatment of those accidents which are daily
occurring in the community, making it a treatise proper and profitable
for the FAMILY LIBRARY, as well as the school-room.



CONTENTS.


 Chapter.                                                        Page.
       1. General Remarks,                                          13
       2. Structure of Man,                                         17
       3. Chemistry of the Human Body,                              25
       4. Anatomy of the Bones,                                     29
       5. Anatomy of the Bones, continued,                          39
       6. Physiology of the Bones,                                  48
       7. Hygiene of the Bones,                                     53
       8. Anatomy of the Muscles,                                   64
       9. Physiology of the muscles,                                76
      10. Hygiene of the Muscles,                                   85
      11. Hygiene of the Muscles, continued,                        96
      12. Anatomy of the Teeth,                                    105
      12. Physiology of the Teeth,                                 109
      12. Hygiene of the Teeth,                                    110
      13. Anatomy of the Digestive Organs,                         113
      14. Physiology of the Digestive Organs,                      124
      15. Hygiene of the Digestive Organs,                         129
      16. Hygiene of the Digestive Organs, continued,              142
      17. Anatomy of the Circulatory Organs,                       154
      18. Physiology of the Circulatory Organs,                    164
      19. Hygiene of the Circulatory Organs,                       172
      20. Anatomy of the Lymphatic Vessels,                        181
      20. Physiology of the Lymphatic Vessels,                     183
      20. Hygiene of the Lymphatic Vessels,                        188
      21. Anatomy of the Secretory Organs.                         192
      21. Physiology of the Secretory Organs,                      193
      21. Hygiene of the Secretory Organs,                         197
      22. Nutrition,                                               200
      22. Hygiene of Nutrition,                                    205
      23. Anatomy of the Respiratory Organs,                       209
      24. Physiology of the Respiratory Organs,                    217
      25. Hygiene of the Respiratory Organs,                       228
      26. Hygiene of the Respiratory Organs, continued,            239
      27. Animal Heat,                                             252
      28. Hygiene of Animal Heat,                                  261
      29. Anatomy of the Vocal Organs,                             268
      29. Physiology of the Vocal Organs,                          272
      30. Hygiene of the Vocal Organs,                             274
      31. Anatomy of the Skin,                                     282
      32. Physiology of the Skin,                                  293
      33. Hygiene of the Skin,                                     301
      34. Hygiene of the Skin, continued,                          311
      35. Appendages of the Skin,                                  322
      36. Anatomy of the Nervous System,                           327
      37. Anatomy of the Nervous System, continued,                340
      38. Physiology of the Nervous System,                        346
      39. Hygiene of the Nervous System,                           358
      40. Hygiene of the Nervous System, continued,                368
      41. The Sense of Touch,                                      378
      42. Anatomy of the Organs of Taste,                          384
      42. Physiology of the Organs of Taste,                       386
      43. Anatomy of the Organs of Smell,                          389
      43. Physiology of the Organs of Smell,                       391
      44. Anatomy of the Organs of Vision,                         394
      45. Physiology of the Organs of Vision,                      404
      45. Hygiene of the Organs of Vision,                         410
      46. Anatomy of the Organs of Hearing,                        414
      47. Physiology of the Organs of Hearing,                     420
      47. Hygiene of the Organs of Hearing,                        422
      48. Means of preserving the Health,                          425
      49. Directions for Nurses,                                   432
          -   -   -   -   -
          APPENDIX,                                                439
          GLOSSARY,                                                451
          INDEX,                                                   463



ANATOMY, &c.

CHAPTER I.

GENERAL REMARKS.


1. ANATOMY is the science which treats of the structure and relations
of the different parts of animals and plants.

2. It is divided into _Vegetable_ and _Animal_ anatomy. The latter of
these divisions is subdivided into _Human_ anatomy, which considers,
exclusively, human beings; and _Comparative_ anatomy, which treats of
the mechanism of the lower orders of animals.

3. PHYSIOLOGY treats of the functions, or uses of the organs of
animals and plants. Another definition is, "the science of life."

4. This is also divided into _Vegetable_ and _Animal_ physiology, as
it treats of the vegetable or animal kingdom; and into _Human_ and
_Comparative_ physiology, as it describes the vital functions of man
or the inferior animals.

5. HYGIENE is the art or science of maintaining health, or a knowledge
of those laws by which health may be preserved.

6. The kingdom of nature is divided into _organic_ and _inorganic_
bodies. Organic bodies possess organs, on whose action depend their
growth and perfection. This division includes animals and plants.
Inorganic bodies are devoid of organs, or instruments of life. In this
division are classed the earths, metals, and other minerals.

  -=-=-=-=-=-=-=-=-=-=-=-=

1. What is anatomy? 2. How is it divided? How is the latter division
subdivided? 3. What is physiology? Give another definition. 4. How is
physiology divided? Give a subdivision. 5. What is hygiene? 6. Define
organic bodies.

  -=-=-=-=-=-=-=-=-=-=-=-=

7. In general, organic matter differs so materially from inorganic,
that the one can readily be distinguished from the other. In the
organic world, every individual of necessity springs from some
_parent, or immediate producing agent_; for while inorganic substances
are formed by chemical laws alone, we see no case of an animal or
plant coming into existence by accident or chance, or chemical
operations.

8. Animals and plants _are supported by means of nourishment_, and die
without it. They also increase in size _by the addition of new
particles of matter to all parts of their substances_; while rocks and
minerals grow only by additions to their surfaces.

9. "Organized bodies always present a combination of both solids and
fluids;--of solids, differing in character and properties, arranged
into organs, and these endowed with functional powers, and so
associated as to form of the whole a single system;--and of fluids,
contained in these organs, and holding such relation to the solids
that the existence, nature, and properties of both mutually and
necessarily depend on each other."

10. Another characteristic is, that organic substances have a _certain
order of parts_. For example, plants possess organs to gain
nourishment from the soil and atmosphere, and the power to give
strength and increase to all their parts. And animals need not only a
digesting and circulating apparatus, but organs for breathing, a
nervous system, &c.

  -=-=-=-=-=-=-=-=-=-=-=-=

6. Define inorganic bodies. 7. What is said of the difference, in
general, between organic and inorganic bodies? 8. What of the growth
of organic and inorganic bodies? 9. What do organized bodies always
present? 10. Give another characteristic of organized substances.

  -=-=-=-=-=-=-=-=-=-=-=-=

11. _Individuality_ is an important characteristic. For instance, a
large rock may be broken into a number of smaller pieces, and yet
every fragment will be rock; but if an organic substance be separated
into two or more divisions, neither of them can be considered an
individual. Closely associated with this is the power of _life_, or
_vitality_, which is the most distinguishing characteristic of organic
structure; since we find nothing similar to this in the inorganic
creation.

12. _The distinction between plants and animals_ is also of much
importance. _Animals grow proportionally in all directions_, while
plants grow upwards and downwards from a collet only. The _food_ of
animals is _organic_, while that of plants is _inorganic_; the latter
feeding entirely upon the elements of the soil and atmosphere, while
the former subsist upon the products of the animal and vegetable
kingdoms. The size of the vegetable is in most cases limited only by
the duration of existence, as a tree continues to put forth new
branches during each period of its life, while the animal, at a
certain time of life, attains the average size of its species.

13. One of the most important distinctions between animals and plants,
is _the different effects of respiration_. Animals consume the oxygen
of the atmosphere, and give off carbonic acid; while plants take up
the carbonic acid, and restore to animals the oxygen, thus affording
an admirable example of the principle of compensation in nature.

14. But the decisive distinctions between animals and plants are
_sensation_ and _voluntary motion_, the power of acquiring a knowledge
of external objects through the senses, and the ability to move from
place to place at will. These are the characteristics which, in their
fullest development in man, show intellect and reasoning powers, and
thereby in a greater degree exhibit to us the wisdom and goodness of
the Creator.

  -=-=-=-=-=-=-=-=-=-=-=-=

11. What is said of the individuality of organized and inorganized
bodies? What is closely associated with this? 12. Give a distinction
between animals and plants as regards growth. The food of animals and
plants. What is said in respect to size? 13. What important
distinction in the effects of respiration of animals and plants? 14.
What are the decisive distinctions between animals and plants?

  -=-=-=-=-=-=-=-=-=-=-=-=

15. DISEASE, which consists in an unnatural condition of the bodily
organs, is in most cases under the control of fixed laws, which we are
capable of understanding and obeying. Nor do diseases come by chance;
they are penalties for violating physical laws. If we carelessly cut
or bruise our flesh, pain and soreness follow, to induce us to be more
careful in the future; or, if we take improper food into the stomach,
we are warned, perhaps immediately by a friendly pain, that we have
violated an organic law.

16. Sometimes, however, the penalty does not directly follow the sin,
and it requires great physiological knowledge to be able to trace the
effect to its true cause. If we possess good constitutions, we are
responsible for most of our sickness; and bad constitutions, or
hereditary diseases, are but the results of the same great law,--the
iniquities of the parents being visited on the children. In this view
of the subject, how important is the study of physiology and hygiene!
For how can we expect to obey laws which we do not understand?

  -=-=-=-=-=-=-=-=-=-=-=-=

15. What is said of disease? 16. Why is the study of physiology and
hygiene important?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER II.

STRUCTURE OF MAN,


17. In the structure of the human body, there is a union of fluids and
solids. These are essentially the same, for the one is readily changed
into the other. There is no fluid that does not contain solid matter
in solution, and no solid matter that is destitute of fluid.

18. In different individuals, and at different periods of life the
proportion of fluids and solids varies. In youth, the fluids are more
abundant than in advanced life. For this reason, the limbs in
childhood are soft and round, while in old age they assume a hard and
wrinkled appearance.

19. The fluids not only contain the materials from which every part of
the body is formed, but they are the medium for conveying the waste,
decayed particles of matter from the system. They have various names,
according to their nature and function; as, the blood, and the bile.

20. The solids are formed from the fluids, and consequently they are
reduced, by chemical analysis, to the same ultimate elements. The
particles of matter in solids are arranged variously; sometimes in
_fi´bres_, (threads,) sometimes in _lam´i-næ_, (plates,) sometimes
homogeneously, as in basement membranes. (Appendix A.)

21. The parts of the body are arranged into _Fi´bres_, _Fas-cic´u-li_,
_Tis´sues_, _Or´gans_, _Ap-pa-ra´tus-es_, and _Sys´tems_.

  -=-=-=-=-=-=-=-=-=-=-=-=

17. What substances enter into the structure of the human body? Are
they essentially the same? 18. What is said of these substances at
different periods of life? 19. What offices do the fluids of the
system perform? 20. What is said of the solids? How are the particles
of matter arranged in solids? 21. Give an arrangement of the parts of
the body.

  -=-=-=-=-=-=-=-=-=-=-=-=

22. A FIBRE is a thread of exceeding fineness. It is either
cylindriform or flattened.

23. A FASCICULUS is the term applied to several fibres united. Its
general characteristics are the same as fibres.

24. A TISSUE is a term applied to several different solids of the
body.

25. An ORGAN is composed of tissues so arranged as to form an
instrument designed for action. The action of an organ is called its
_function_, or use.

_Example._ The liver is an organ, and the secretion of the bile from
the blood is one of its functions.[1]

   [1] Where examples and observations are given or experiments
       suggested, let the pupil mention other analogous ones.

26. An APPARATUS is an assemblage of organs designed to produce
certain results.

_Example._ The digestive apparatus consists of the teeth, stomach,
liver, &c., all of which aid in the digestion of food.

[Illustration: Fig. 2. Represents a portion of broken muscular fibre of
animal life, (magnified about seven hundred diameters.)]

27. The term SYSTEM is applied to an assemblage of organs arranged
according to some plan, or method; as the nervous system, the
respiratory system.

  -=-=-=-=-=-=-=-=-=-=-=-=

22. Define a fibre. 23. Define a fasciculus. 24. Define a tissue. 25.
Define an organ. What is the action of an organ called? Give examples.
_Mention other examples._ 26. What is an apparatus? Give an example
27. How is the term system applied?

  -=-=-=-=-=-=-=-=-=-=-=-=

28. A TISSUE is a simple form of organized animal substance. It is
flexible, and formed of fibres interwoven in various ways; as, the
cellular tissue.

29. However various all organs may appear in their structure and
composition, it is now supposed that they can be reduced to a few
tissues; as, the _Cel´lu-lar_, _Os´se-ous_, _Mus´cu-lar_, _Mu´cous_,
_Ner´vous_, &c. (Appendix B.)

30. The CELLULAR TISSUE,[2] now called the _areolar tissue_, consists
of small fibres, or bands, interlaced in every direction, so as to
form a net-work, with numerous interstices that communicate freely
with each other. These interstices are filled, during life, with a
fluid resembling the serum of blood. The use of the areolar tissue is
to connect together organs and parts of organs, and to envelop, fix,
and protect the vessels and nerves of organs.

   [2] The _Cellular_, _Serous_, _Dermoid_, _Fibrous_, and _Mucous
       tissues_ are very generally called _membranes_.

[Illustration: Fig. 3. Arrangement of fibres of the cellular tissue
magnified one hundred and thirty diameters.]

  -=-=-=-=-=-=-=-=-=-=-=-=

28. What is a tissue? 29. What is said respecting the structure and
composition of the various organs? Name the primary membranes. 30.
Describe the cellular tissue. How are the cells imbedded in certain
tissues? Give observation 1st, relative to the cellular tissue.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observations._ 1st. When this fluid becomes too great in quantity, in
consequence of disease, the patient labors under general dropsy. The
swelling of the feet when standing, and their return to a proper shape
during the night, so often noticed in feeble persons, furnish a
striking proof both of the existence and peculiarity of this tissue,
which allows the fluid to flow from cell to cell, until it settles in
the lower extremities.

2d. The free communication between the cells is still more remarkable
in regard to air. Sometimes, when an accidental opening has been made
from the air-cells of the lungs into the contiguous cellular tissue,
the air in respiration has penetrated every part until the whole body
is so inflated as to occasion suffocation. Butchers often avail
themselves of the knowledge of this fact, and inflate their meat to
give it a fat appearance.

31. "Although this tissue enters into the composition of all organs,
it never loses its own structure, nor participates in the functions of
the organ of which it forms a part. Though present in the nerves, it
does not share in their sensibility; and though it accompanies every
muscle and every muscular fibre, it does not partake of the
irritability which belongs to these organs."

32. Several varieties of tissue are formed from the cellular; as, the
_Se´rous_, _Der´moid_, _Fi´brous_, and several others.

33. The SEROUS TISSUE lines all the closed, or sac-like cavities of
the body; as, the chest, joints, and abdomen. It not only lines these
cavities, but is reflected, and invests the organs contained in them.
The liver and the lungs are thus invested. This membrane is of a
whitish color, and smooth on its free surfaces. These surfaces are
kept moist, and prevented from adhering by a _se´rous_ fluid, which is
separated from the blood. The use of this membrane is to separate
organs and also to facilitate the movement of one part upon another,
by means of its moist, polished surfaces.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give observation 2d. 31. What is said of the identity of this tissue?
32. Name the varieties of tissue formed from the cellular. 33. Where
is the serous tissue found? What two offices does it perform? Give its
structure. What is the use of this membrane?

  -=-=-=-=-=-=-=-=-=-=-=-=

34. The DERMOID TISSUE covers the outside of the body. It is called
the _cu´tis_, (skin.) This membrane is continuous with the mucous at
the various orifices of the body, and in these situations, from the
similarity of their structure, it is difficult to distinguish between
them.

_Observations._ 1st. In consequence of the continuity and similarity
of structure, there is close sympathy between the mucous and dermoid
membranes. If the functions of the skin are disturbed, as by a chill,
it will frequently cause a catarrh, (cold,) or diarrhoea. Again, in
consequence of this intimate sympathy, these complaints can be
relieved by exciting a free action in the vessels of the skin.

2d. It is no uncommon occurrence that diseased or irritated conditions
of the mucous membrane of the stomach or intestines produce diseases
or irritations of the skin, as is seen in the rashes attendant on
dyspepsia, and eating certain species of fish. These eruptions of the
skin can be relieved by removing the diseased condition of the
stomach.

35. The FIBROUS TISSUE consists of longitudinal, parallel fibres,
which are closely united. These fibres, in some situations, form a
thin, dense, strong membrane, like that which lines the internal
surface of the skull, or invests the external surface of the bones.
In other instances, they form strong, inelastic bands, called
_lig´a-ments_, which bind one bone to another. This tissue also
forms _ten´dons_, (white cords,) by which the muscles are attached
to the bones.

_Observation._ In the disease called rheumatism, the fibrous tissue is
the part principally affected; hence the joints, where this tissue is
most abundant, suffer most from this affection.

  -=-=-=-=-=-=-=-=-=-=-=-=

34. Describe the dermoid tissue. What is said of the sympathy between
the functions of the skin and mucous membrane? Give another instance
of the sympathy between these membranes. 35. Of what does the fibrous
tissue consist? How do these appear in some situations? How in others?
What tissue is generally affected in rheumatism?

  -=-=-=-=-=-=-=-=-=-=-=-=

36. The ADIPOSE TISSUE is so arranged as to form distinct bags, or
cells. These contain a substance called _fat_. This tissue is
principally found beneath the skin, abdominal muscles, and around the
heart and kidneys; while none is found in the brain, eye, ear, nose,
and several other organs.

_Observation._ In those individuals who are corpulent, there is in
many instances, a great deposit of this substance. This tissue
accumulates more readily than others when a person becomes gross, and
is earliest removed when the system emaciates, in acute or chronic
diseases. Some of the masses become, in some instances, enlarged.
These enlargements are called _adipose_, or _fatty tumors_.

[Illustration: Fig. 4. 1, A portion of the adipose tissue. 2, 2, 2,
Minute bags containing fat. 3, A cluster of these bags, separated and
suspended.]

37. The CARTILAGINOUS TISSUE is firm, smooth, and highly elastic.
Except bone, it is the hardest part of the animal frame. It tips the
ends of the bones that concur in forming a joint. Its use is to
facilitate the motion of the joints by its smooth surface, while its
elastic character diminishes the shock that would otherwise be
experienced if this tissue were inelastic.

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36. Describe the adipose tissue. Where does this tissue principally
exist? Give observation in regard to the adipose tissue. 37. Describe
the cartilaginous tissue. What is its use?

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38 The OSSEOUS TISSUE, in composition and arrangement of matter,
varies at different periods of life, and in different bones. In some
instances, the bony matter is disposed in plates, while in other
instances, the arrangement is cylindrical. Sometimes, the bony matter
is dense and compact; again, it is spongy, or porous. In the centre of
the long bones, a space is left which is filled with a fatty
substance, called _mar´row_.

_Observation._ Various opinions exist among physiologists in regard to
the use of marrow. Some suppose it serves as a reservoir of
nourishment, while others, that it keeps the bones from becoming dry
and brittle. The latter opinion, however, has been called in question,
as the bones of the aged man contain more marrow than those of the
child, and they are likewise more brittle.

[Illustration: Fig. 5. A section of the femur, (thigh-bone.) 1, 1, The
extremities, showing a thin plate of compact texture, which covers small
cells, that diminish in size, but increase in number, as they approach
the articulation. 2, 2, The walls of the shaft, which are very firm and
solid. 3, The cavity that contains the marrow.]

39. The MUSCULAR TISSUE is composed of many fibres, that unite to form
fasciculi, each of which is enclosed in a delicate layer of cellular
tissue. Bundles of these fasciculi constitute a muscle.

_Observation._ A piece of boiled beef will clearly illustrate the
arrangement of muscular fibre.

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38. What is said of the osseous tissue? How is the bony matter
arranged in different parts of the animal frame? What is said of the
use of marrow? 39. Of what is the muscular tissue composed? How may
the arrangement of muscular fibre be illustrated?

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40. The MUCOUS TISSUE differs from the serous by its lining all
the cavities which communicate with the air. The nostrils, the
mouth, and the stomach afford examples. The external surface of this
membrane, or that which is exposed to the air, is soft, and bears some
resemblance to the downy rind of a peach. It is covered by a viscid
fluid called _mu´cus_. This is secreted by small _gland-cells_,
called _ep-i-the´li-a_, or secretory cells of the mucous membrane.
The use of this membrane and its secreted mucus is to protect the
inner surface of the cavities which it lines.

_Observation._ A remarkable sympathy exists between the remote parts
of the mucous membrane. Thus the condition of the stomach may be
ascertained by an examination of the tongue.

41. The NERVOUS TISSUE consists of soft, pulpy matter, enclosed in
a sheath, called _neu-ri-lem´a_. This tissue consists of two
substances. The one, of a pulpy character and gray color, is called
_cin-e-ri´tious_, (ash-colored.) The other, of a fibrous character and
white, is named _med´ul-la-ry_, (marrow-like.) In every part of the
nervous system both substances are united, with the exception of the
nervous fibres and filaments, which are solely composed of the
medullary matter enclosed in a delicate sheath.

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40. How does the mucous differ from the serous tissue? What is the
appearance of the external surface of this membrane? Where is the
mucus secreted? What is the use of this membrane? 41. Of what does the
nervous tissue consist? Describe the two substances that enter into
the composition of the nervous tissue.

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER III

CHEMISTRY OF THE HUMAN BODY.


42. An ULTIMATE ELEMENT is the simplest form of matter with which we
are acquainted; as gold, iron, &c.

43. These elements are divided into _metallic_ and _non-metallic_
substances. The metallic substances are _Po-tas´si-um_, _So´di-um_,
_Cal´ci-um_, _Mag-ne´si-um_, _A-lu´min-um_, _I´ron_, _Man´ga-nese_, and
_Cop´per_. The non-metallic substances are _Ox´y-gen_, _Hy´dro-gen_,
_Car´bon_, _Ni´tro-gen_, _Si-li´-ci-um_, _Phos´phor-us_, _Sul´phur_,
_Chlo´rine_, and a few others.

44. POTASH (potassium united with oxygen) is found in the blood, bile,
perspiration, milk, &c.

45. SODA (sodium combined with oxygen) exists in the muscles, and in
the same fluids in which potash is found.

46. LIME (calcium combined with oxygen) forms the principal ingredient
of the bones. The lime in them is combined with phosphoric and
carbonic acid.

47. MAGNESIA (magnesium combined with oxygen) exists in the bones,
brain, and in some of the animal fluids; as milk.

48. SILEX (silicium combined with oxygen) is contained in the hair and
in some of the secretions.

49. IRON forms the coloring principle of the red globules of the
blood, and is found in every part of the system.

_Observation._ As metallic or mineral substances enter into the
ultimate elements of the body, the assertion that all minerals are
poisonous, however small the quantity, is untrue.

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42. What is an ultimate element? Give examples. 43. How are they
divided? Name the metallic substances. Name the non-metallic
substances. 44. What is said of potash? 45. Of soda? 46. Of lime? 47.
Of magnesia? 48. Of silex? 49. What forms the coloring principle of
the blood? What is said of mineral substances?

  -=-=-=-=-=-=-=-=-=-=-=-=

50. OXYGEN is contained in all the fluids and solids of the body. It
is almost entirely derived from the inspired air and water. It is
expelled in the form of carbonic acid and water from the lungs and
skin. It is likewise removed in the other secretions.

51. HYDROGEN is found in all the fluids and in all the solids of
the body. It is derived from the food, as well as from water and
other drinks. It exists in the greatest abundance in the impure,
dark-colored blood of the system. It is removed by the agency of the
kidneys, skin, lungs, and other excretory organs.

52. CARBON is an element in the oil, fat, albumen, fibrin, gelatin,
bile, and mucus. This element likewise exists in the impure blood in
the form of carbonic acid gas. Carbon is obtained from the food, and
discharged from the system by the secretions and respiration.

53. NITROGEN is contained in most animal matter, but is most abundant
in fibrin. It is not contained in fat and a few other substances.

_Observation._ The peculiar smell of animal matter when burning is
owing to nitrogen. This element combined with hydrogen forms
_am-mo´ni-a_, (hartshorn,) when animal matter is in a state of
putrefaction.

54. PHOSPHORUS is contained in many parts of the system, but more
particularly in the bones. It is generally found in combination with
oxygen, forming _phosphoric acid_. The phosphoric acid is usually
combined with alkaline bases; as lime in the bones, forming phosphate
of lime.

55. SULPHUR exists in the bones, muscles, hair, and nails. It is
expelled from the system by the skin and intestines.

56. CHLORINE is found in the blood, gastric juice, milk, perspiration,
and saliva.

  -=-=-=-=-=-=-=-=-=-=-=-=

50. What is said of oxygen? 51. Of hydrogen? 52. What is said of
carbon? 53. Of nitrogen? How is ammonia formed? 54. What is said of
phosphorus? 55. What is said of sulphur? 56. Of chlorine?

  -=-=-=-=-=-=-=-=-=-=-=-=

57. PROXIMATE ELEMENTS are forms of matter that exist in organized
bodies in abundance, and are composed chiefly of oxygen, hydrogen,
carbon, and nitrogen, arranged in different proportions. They exist
already formed, and may be separated in many instances, by heat or
mechanical means. The most important compounds are _Al-bu´men_,
_Fi´brin_, _Gel´a-tin_, _Mu´cus_, _Fat_, _Ca´se-ine_, _Chon´drine_,
_Lac´tic acid_, and _Os´ma-zome_.

58. ALBUMEN is found in the body, both in a fluid and solid form. It
is an element of the skin, glands, hair, and nails, and forms the
principal ingredient of the brain. Albumen is without color, taste, or
smell, and it coagulates by heat, acids, and alcohol.

_Observation._ The white of an egg is composed of albumen, which can
be coagulated or hardened by alcohol. As albumen enters so largely
into the composition of the brain, is not the impaired intellect and
moral degradation of the inebriate attributable to the effect of
alcohol in hardening the albumen of this organ?

59. FIBRIN exists abundantly in the blood, chyle, and lymph. It
constitutes the basis of the muscles. Fibrin is of a whitish color,
inodorous, and insoluble in cold water. It differs from albumen by
possessing the property of coagulating at all temperatures.

_Observation._ Fibrin may be obtained by washing the thick part of
blood with cold water; by this process, the red globules, or coloring
matter, are separated from this element.

60. GELATIN is found in nearly all the solids, but it is not known to
exist in any of the fluids. It forms the basis of the cellular tissue,
and exists largely in the skin, bones, ligaments, and cartilages.

  -=-=-=-=-=-=-=-=-=-=-=-=

57. What are proximate elements? Do they exist already formed in
organized bodies? Name the most important compounds. 58. What is said
of albumen? Give observation relative to this element. 59. Of fibrin?
How does albumen differ from fibrin? How can fibrin be obtained? 60.
What is said of gelatin?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Gelatin is known from other organic principles by its
dissolving in warm water, and forming "jelly." When dry, it forms the
hard, brittle substance, called _glue_. Isinglass, which is used in
the various mechanical arts, is obtained from the sounds of the
sturgeon.

61. MUCUS is a viscid fluid secreted by the gland-cells, or epithelia.
Various substances are included under the name of mucus. It is
generally alkaline, but its true chemical character is imperfectly
understood. It serves to moisten and defend the mucous membrane. It is
found in the cuticle, brain, and nails; and is scarcely soluble in
water, especially when dry. (Appendix C.)

62. OSMAZOME is a substance of an aromatic flavor. It is of a
yellowish-brown color, and is soluble both in water and alcohol, but
does not form a jelly by concentration. It is found in all the fluids,
and in some of the solids; as the brain.

_Observation._ The characteristic odor and taste of soup are owing to
osmazome.

63. There are several acids found in the human system; as the
_A-ce´tic_, _Ben-zo´ic_, _Ox-al´ic_, _U´ric_, and some other
substances, but not of sufficient importance to require a particular
description.

  -=-=-=-=-=-=-=-=-=-=-=-=

How is it known from other organic principles? 61. What is said of
mucus? 62. Of osmazome? To what are the taste and odor of soup owing?
63. What acids are found in the system?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER IV.

THE BONES.


64. The bones are firm and hard, and of a dull white color. In all the
higher orders of animals, among which is man, they are in the interior
of the body, while in lobsters, crabs, &c., they are on the outside,
forming a case which protects the more delicate parts from injury.

65. In the mechanism of man, the variety of movements he is called to
perform requires a correspondent variety of component parts, and the
different bones of the system are so admirably adapted to each other,
that they admit of numerous and varied motions.

66. When the bones composing the skeleton are united by natural
ligaments, they form what is called a _natural skeleton_, when united
by wires, what is termed an _artificial skeleton_.

67. The elevations, or protuberances, of the bones are called
_proc´es-ses_, and are, generally, the points of attachment for the
muscles and ligaments.


ANATOMY OF THE BONES.

68. The BONES are composed of both animal and earthy matter. The
earthy portion of the bones gives them solidity and strength, while
the animal part endows them with vitality.

  -=-=-=-=-=-=-=-=-=-=-=-=

64. What is said of the bones? 65. Is there an adaptation of the bones
of the system to the offices they are required to perform? 66. What is
a natural skeleton? What an artificial? 67. What part of the bones are
called processes? 68-73. _Give the structure of the bones._ 68. Of
what are the bones composed? What are the different uses of the
component parts of the bones?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Experiments._ 1st. To show the earthy without the animal matter, burn
a bone in a clear fire for about fifteen minutes, and it becomes white
and brittle, because the gelatin, or animal matter of the bone, has
been destroyed.

2d. To show the animal without the earthy matter of the bones, immerse
a slender bone for a few days in a weak acid, (one part muriatic acid
and six parts water,) and it can then be bent in any direction. In
this experiment, the acid has removed the earthy matter, (carbonate
and phosphate of lime,) yet the form of the bone is unchanged.

69. The bones are formed from the blood, and are subjected to several
changes before they are perfected. At their early formative stage,
they are cartilaginous. The vessels of the cartilage, at this period,
convey only the _lymph_, or white portion of the blood; subsequently,
they convey red blood. At this time, true ossification (the deposition
of phosphate and carbonate of lime) commences at certain points, which
are called _the points of ossification_.

70. Most of the bones are formed of several pieces, or centres of
ossification. This is seen in the long bones which have their
extremities separated from the body by a thin partition of cartilage.
It is some time before these separate pieces are united to form one
bone.

71. When the process of ossification is completed, there is still a
constant change in the bones. They increase in bulk, and become less
vascular, until middle age. In advanced life, the elevations upon
their surface and near the extremities become more prominent,
particularly in individuals accustomed to labor. As a person advances
in years, the vitality diminishes, and in extreme old age, the earthy
substance predominates; consequently, the bones are extremely
brittle.

  -=-=-=-=-=-=-=-=-=-=-=-=

How can the earthy matter of the bones be shown? The animal? 69.
What is the appearance of the bones in their early formative stage?
When does true ossification commence? 70. How are most of the bones
formed? 71. What is said of the various changes of the bones after
ossification?

  -=-=-=-=-=-=-=-=-=-=-=-=

72. The fibrous membrane that invests the bones is called
_per-i-os´te-um_; that which covers the cartilages is called
_per-i-chon´dri-um_. When this membrane invests the skull, it is
called _per-i-cra´ni-um_.

[Illustration: Fig. 6. A section of the knee-joint. The lower part of the
femur, (thigh-bone,) and upper part of the tibia, (leg-bone,) are seen
ossified at 1, 1. The cartilaginous extremities of the two bones are seen
at _d_, _d_. The points of ossification of the extremities, are seen at
2, 2. The patella, or knee-pan, is seen at _c_. 3, A point, or centre of
ossification.]

73. The PERIOSTEUM is a firm membrane immediately investing the bones,
except where they are tipped with cartilage, and the crowns of the
teeth, which are protected by enamel. This membrane has minute nerves,
and when healthy, possesses but little sensibility. It is the
nutrient membrane of the bone, endowing its exterior with vitality; it
also gives insertion to the tendons and connecting ligaments of the
joints.

  -=-=-=-=-=-=-=-=-=-=-=-=

72. What is the membrane called that invests the bones? That covers
the cartilage? That invests the skull? Explain fig. 6. 73. Describe
the periosteum.

  -=-=-=-=-=-=-=-=-=-=-=-=

74. There are two hundred and eight[3] bones in the human body,
beside the teeth. These, for convenience, are divided into four
parts: 1st. The bones of the _Head_. 2d. The bones of the _Trunk_.
3d. The bones of the _Upper Extremities_. 4th. The bones of the
_Lower Extremities_.

   [3] Some anatomists reckon more than this number, others less, for
       the reason that, at different periods of life, the number of
       pieces of which one bone is formed, varies. _Example._ The
       breast-bone, in infancy, has _eight_ pieces; in youth, _three_;
       in old age, but _one_.

75. The bones of the HEAD are divided into those of the _Skull_,
_Ear_, and _Face_.

76. The SKULL is composed of eight bones. They are formed of two
plates, or tablets of bony matter, united by a porous portion of bone.
The external tablet is fibrous and tough; the internal plate is dense
and hard, and is called the _vit´re-ous_, or glassy table. These
tough, hard plates are adapted to resist the penetration of sharp
instruments, while the different degrees of density possessed by the
two tablets, and the intervening spongy bone, serve to diminish the
vibrations that would occur in falls or blows.

77. The skull is convex externally, and at the base much thicker than
at the top or sides. The most important part of the brain is placed
here, completely out of the way of injury, unless of a very serious
nature. The base of the cranium, or skull, has many projections,
depressions, and apertures; the latter affording passages for the
nerves and blood-vessels.

  -=-=-=-=-=-=-=-=-=-=-=-=

74. How many bones in the human body? How are they divided? 75-81.
_Give the anatomy of the bones of the head._ 75. How are the bones of
the head divided? 76. Describe the bones of the skull. 77. What is the
form of the skull? What does the base of the skull present?

  -=-=-=-=-=-=-=-=-=-=-=-=

78. The bones of the cranium are united by ragged edges, called
_sut´ures_. The edges of each bone interlock with each other,
producing a union, styled, in carpentry, _dovetailing_. They
interrupt, in a measure, the vibrations produced by external blows,
and also prevent fractures from extending as far as they otherwise
would, in one continued bone. From infancy to the twelfth year, the
sutures are imperfect; but, from that time to thirty-five or forty,
they are distinctly marked; in old age, they are nearly obliterated.

[Illustration: Fig. 7. 1, 1, The coronal suture at the front and upper
part of the skull, or cranium. 2, The sagittal suture on the top of the
skull. 3, 3, The lambdoidal suture at the back part of the cranium.]

79. We find as great a diversity in the form and texture of the
skull-bone, as in the expression of the face. The head of the New
Hollander is small; that of the African is compressed; while the
Caucasian is distinguished for the beautiful oval form of the head.
The Greek skulls, in texture, are close and fine, while the Swiss are
softer and more open.

  -=-=-=-=-=-=-=-=-=-=-=-=

78. How are the bones of the skull united? What are the uses of the
sutures? Mention the appearance of the sutures at different ages. What
does fig. 7 represent? 79. What is said respecting the form and
texture of the skull in different nations?

  -=-=-=-=-=-=-=-=-=-=-=-=

80. In each EAR are four very small bones. They aid in hearing.

81. In the FACE are fourteen bones, some of which serve for the
attachment of powerful muscles, which are more or less called into
action in masticating food; others retain in place the soft parts of
the face.

[Illustration: Fig. 8. 1, The frontal, or bone of the forehead. 2. The
parietal bone. 3, The temporal bone. 4, The zygomatic process of the
temporal bone. 5, The malar (cheek) bone. 6, The superior maxillary bone,
(upper jaw.) 7, The vomer, that separates the cavities of the nose. 8,
The inferior maxillary bone, (lower jaw.) 9. The cavity for the eye.]

82. The TRUNK has fifty-four bones--twenty-four _Ribs_; twenty-four
bones in the _Spi´nal Col´umn_, (back-bone;) four in the _Pel´vis_;
the _Ster´num_, (breast-bone;) and the _Os hy-oid´es_, (the bone at
the base of the tongue.) They are so arranged as to form, with the
soft parts attached to them, two cavities, called the _Tho´rax_
(chest) and _Ab-do´men_.

  -=-=-=-=-=-=-=-=-=-=-=-=

80. How many bones in the ear? 81. How many bones in the face? What is
their use? Explain fig. 8. 82-94. _Give the anatomy of the bones of
the trunk._ 82. How many bones in the trunk? Name them. What do they
form by their arrangement?

  -=-=-=-=-=-=-=-=-=-=-=-=

83. The THORAX is formed by the sternum in front; the ribs, at the
sides; and the twelve dorsal bones of the spinal column, posteriorly.
The natural form of the chest is a cone, with its apex above; but
fashion, in many instances, has nearly inverted this order. This
cavity contains the lungs, heart, and large blood-vessels.

[Illustration: Fig. 9. 1, The first bone of the sternum, (breast-bone.)
2. The second bone of the sternum. 3, The cartilage of the sternum. 4,
The first dorsal vertebra, (a bone of the spinal column.) 5, The last
dorsal vertebra. 6, The first rib. 7, Its head. 8, Its neck. 9, Its
tubercle. 10, The seventh, or last true rib. 11, The cartilage of the
third rib. 12, The floating ribs.]

84. The STERNUM is composed of eight pieces in the child. These unite
and form but three parts in the adult. In youth, the two upper
portions are converted into bone, while the lower portion remains
cartilaginous and flexible until extreme old age, when it is often
converted into bone.

85. The RIBS are connected with the spinal column, and increase in
length as far as the seventh. From this they successively become
shorter. The direction of the ribs from above, downward, is oblique,
and their curve diminishes from the first to the twelfth. The external
surface of each rib is convex; the internal, concave. The inferior, or
lower ribs, are, however, very flat.

  -=-=-=-=-=-=-=-=-=-=-=-=

83. Describe the thorax. Explain fig. 9. 84. Describe the sternum. 85.
Describe the ribs.

  -=-=-=-=-=-=-=-=-=-=-=-=

86. The seven upper ribs are united to the sternum, through the medium
of cartilages, and are called the _true ribs_. The cartilages of the
next three are united with each other, and are not attached to the
sternum; these are called _false ribs_. The lowest two are called
_floating ribs_, as they are not connected either with the sternum or
the other ribs.

87. The SPINAL COLUMN is composed of twenty-four pieces of bone. Each
piece is called a _vert´e-bra_. On examining one of the bones, we find
seven projections, called _processes_; four of these, that are
employed in binding the bones together, are called _articulating_
processes; two of the remaining are called the _transverse_; and the
other, the _spinous_. The last three give attachment to the muscles of
the back.

88. The large part of the vertebra, called the body, is round and
spongy in its texture, like the extremity of the round bones. The
processes are of a more dense character. The projections are so
arranged that a tube, or canal, is formed immediately behind the
bodies of the vertebræ, in which is placed the _me-dul´la spi-na´lis_,
(spinal cord,) sometimes called the pith of the back-bone.

89. Between these joints, or vertebræ, is a peculiar and highly
elastic substance, which much facilitates the bending movements of the
back. This compressible cushion of cartilage also serves the important
purpose of diffusing and diminishing the shock in walking, running, or
leaping, and tends to protect the delicate texture of the brain.

  -=-=-=-=-=-=-=-=-=-=-=-=

86. How are the ribs united to the sternum? 87. Describe the spinal
column. 88. Give the structure of the vertebra. Where is the spinal
cord placed? 89. What is placed between each vertebra? What is its
use?

  -=-=-=-=-=-=-=-=-=-=-=-=

90. Another provision for the protection of the brain, which bears
convincing proof of the wisdom and beneficence of the Creator, is the
antero-posterior, or forward and backward curve of the spinal column.
Were it a straight column, standing perpendicularly, the slightest
jar, in walking, would cause it to recoil with a sudden jerk; because,
the weight bearing equally, the spine would neither yield to the one
side nor the other. But, shaped as it is, we find it yielding in the
direction of the curves, and thus the force of the shock is diffused.

[Illustration: Fig. 10. A vertebra of the neck. 1, The body of the
vertebra. 2, The spinal canal. 4, The spinous process, cleft at its
extremity. 5, The transverse process. 7, The inferior articulating
process. 8, The superior articulating process.]

[Illustration: Fig. 11. 1, The cartilaginous substance that connects the
bodies of the vertebræ. 2, The body of the vertebra. 3, The spinous
process. 4, 4, The transverse processes. 5, 5, The articulating
processes. 6, 6, A portion of the bony bridge that assists in forming the
spinal canal, (7.)]

_Observation._ A good idea of the structure of the vertebræ may be
obtained by examining the spinal column of a domestic animal, as the
dog, cat, or pig.

91. The PELVIS is composed of four bones; the two _in-nom-i-na´ta_,
(nameless bones,) the _sa´crum_, and the _coc´cyx_.

92. The INNOMINATUM, in the child, consists of three pieces. These,
in the adult, become united, and constitute but one bone. In the sides
of these bones is a deep socket, or depression, like a cup, called the
_ac-e-tab´u-lum_, in which the round head of the thigh-bone is
placed.

  -=-=-=-=-=-=-=-=-=-=-=-=

90. What is said of the curves of the spinal column? What is
represented by fig. 10? By fig. 11? How can the structure of the
vertebræ be seen? 91. Of how many bones is the pelvis composed? 92.
What is said of the innominatum in the child?

  -=-=-=-=-=-=-=-=-=-=-=-=

93. The SACRUM, so called because the ancients offered it in
sacrifices, is a wedge-shaped bone, that is placed between the
innominata, and to which it is bound by ligaments. Upon its upper
surface it connects with the lower vertebra. At its inferior, or lower
angle, it is united to the coccyx. It is concave upon its anterior,
and convex upon its posterior surface.

[Illustration: Fig. 12. 1, 1, The innominata, (nameless bones.) 2, The
sacrum. 3, The coccyx. 4, 4, The acetabulum. a, a, The pubic portion of
the innominata. d, The arch of the pubes; e, The junction of the sacrum
and lower lumbar vertebra.]

94. The COCCYX, in infants, consists of several pieces, which, in
youth, become united and form one bone. This is the terminal extremity
of the spinal column.

  -=-=-=-=-=-=-=-=-=-=-=-=

In the adult? Describe the acetabulum. 93. Describe the sacrum.
Explain fig. 12. 94. Describe the coccyx.

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER V.

ANATOMY OF THE BONES, CONTINUED


95. The bones of the upper and lower limbs are enlarged at each
extremity, and have projections, or processes. To these, the tendons
of muscles and ligaments are attached, which connect one bone with
another. The shaft of these bones is cylindrical and hollow, and in
structure, their exterior surface is hard and compact, while the
interior portion is of a reticulated character. The enlarged
extremities of the round bones are more porous than the main shaft.

96. The UPPER EXTREMITIES contain sixty-four bones--the _Scap´u-la_,
(shoulder-blade;) the _Clav´i-cle_, (collar-bone;) the _Hu´mer-us_,
(first bone of the arm;) the _Ul´na_ and _Ra´di-us_, (bones of the
fore-arm;) the _Car´pus_, (wrist;) the _Met-a-car´pus_, (palm of the
hand;) and the _Pha-lan´ges_, (fingers and thumb.)

97. The CLAVICLE is attached, at one extremity, to the sternum; at the
other, it is united to the scapula. It is shaped like the Italic
_[s]_. Its use is to keep the arms from sliding toward the breast.

98. The SCAPULA is situated upon the upper and back part of the chest.
It is flat, thin, and of a triangular form. This bone lies upon and is
retained in its position by muscles. By their contractions it may be
moved in different directions.

99. The HUMERUS is cylindrical, and is joined at the elbow with the
ulna of the fore-arm; at the scapular extremity, it is lodged in the
_glenoid_ cavity, where it is surrounded by a membranous bag, called
the _capsular ligament_.

  -=-=-=-=-=-=-=-=-=-=-=-=

95-104. _Give the anatomy of the bones of the upper extremities._ 95.
Give the structure of the bones of the extremities. 96. How many bones
in the upper extremities? Name them. 97. Give the attachments of the
clavicle. What is its use? 98. Describe the scapula. How is it
retained in its position? 99. Describe the humerus.

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[Illustration: Fig. 13. 1, The shaft of the humerus. 2, The large, round
head that is placed in the glenoid cavity. 3, 4, Processes, to which
muscles are attached. 5, A process, called the external elbow. 6, A
process, called the internal elbow. 7, The articulating surface upon
which the ulna rolls.]

[Illustration: Fig. 14. 1, The body of the ulna. 2, The shaft of the
radius. 3, The upper articulation of the radius and ulna. 4, Articulating
cavity, in which the lower extremity of the humerus is placed. 5, Upper
extremity of the ulna, called the olecranon process, which forms the
point of the elbow. 6, Space between the radius and ulna, filled by the
intervening ligament. 7, Styloid process of the ulna. 8, Surface of the
radius and the ulna, where they articulate with the bones of the wrist.
9, Styloid process of the radius.]

100. The ULNA articulates with the humerus at the elbow, and forms a
perfect hinge-joint. This bone is situated on the inner side of the
fore-arm.

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What is represented by fig. 13? By fig. 14? 100. Describe the ulna.

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101. The RADIUS articulates with the bones of the carpus and forms the
wrist-joint. This bone is situated on the outside of the fore-arm,
(the side on which the thumb is placed.) The ulna and radius, at their
extremities, articulate with each other, by which union the hand is
made to rotate, permitting its complicated and varied movements.

102. The CARPUS is composed of eight bones, ranged in two rows, and so
firmly bound together, as to permit only a small amount of movement.

[Illustration: Fig. 15. U, The ulna. R, The radius. S, The scaphoid bone.
L, The semilunar bone. C, The cuneiform bone. P, The pisiform bone. These
four form the first row of carpal bones. T, T, The trapezium and
trapezoid bones. M, The os magnum. U, The unciform bone. These four form
the second row of carpal bones. 1, 1, 1, 1, 1, The metacarpal bones of
the thumb and fingers.]

[Illustration: Fig. 16. 10, 10, 10, The metacarpal bones of the hand. 11,
11, First range of finger-bones. 12, 12, Second range of finger-bones.
13, 13, Third range of finger-bones. 14, 15, Bones of the thumb.]

103. The METACARPUS is composed of five bones, upon four of which the
first range of the finger-bones is placed; and upon the other, the
first bone of the thumb. The five metacarpal bones articulate with the
second range of carpal bones.

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101. The radius. 102. How many bones in the carpus? How are they
ranged? 103. Describe the metacarpus.

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104. The PHALANGES of the fingers have three ranges of bones, while
the thumb has but two.

_Observation._ The wonderful adaptation of the hand to all the
mechanical offices of life, is one cause of man's superiority over the
rest of creation. This arises from the size and strength of the
thumbs, and the different lengths of the fingers.

105. The LOWER EXTREMITIES contain sixty bones--the _Fe´mur_,
(thigh-bone;) the _Pa-tel´la_, (knee-pan;) the _Tib´i-a_, (shin-bone;)
the _Fib´u-la_, (small bone of the leg;) the _Tar´sus_, (instep;) the
_Met-a-tar´sus_, (middle of the foot;) and the _Pha-lan´ges_, (toes.)

106. The FEMUR is the longest bone in the system. It supports the
weight of the head, trunk, and upper extremities. The large, round
head of this bone is placed in the acetabulum. This articulation is a
perfect specimen of the ball and socket joint.

107. The PATELLA is a small bone connected with the tibia by a strong
ligament. The tendon of the _ex-tens´or_ muscles of the leg is
attached to its upper edge. This bone is placed on the anterior part
of the lower extremity of the femur, and acts like a pulley, in the
extension of the limb.

108. The TIBIA is the largest bone of the leg. It is of a triangular
shape, and enlarged at each extremity.

109. The FIBULA is a smaller bone than the tibia, but of similar
shape. It is firmly bound to the tibia, at each extremity.

110. The TARSUS is formed of seven irregular bones, which are so
firmly bound together as to permit but little movement.

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104. How many ranges of bones have the phalanges? 105-112. _Give the
anatomy of the bones of the lower extremities._ 105. How many bones in
the lower extremities? Name them. 106. Describe the femur. 107.
Describe the patella. What is its function? 108. What is the largest
bone of the leg called? What is its form? 109. What is said of the
fibula? 110. Describe the tarsus.

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[Illustration: Fig. 17. 1, The shaft of the femur, (thigh-bone.) 2, A
projection, called the trochantar minor, to which are attached some
strong muscles. 4, The trochantar major, to which the large muscles of
the hip are attached. 3, The head of the femur. 5, The external
projection of the femur, called the external condyle. 6, The internal
projection, called the internal condyle. 7, The surface of the lower
extremity of the femur, that articulates with the tibia, and upon which
the patella slides.]

[Illustration: Fig. 18. 1, The tibia. 5, The fibula. 8, The space between
the two, filled with the inter-osseous ligament. 6, The junction of the
tibia and fibula at their upper extremity. 2, The external malleolar
process, called the external ankle. 3, The internal malleolar process,
called the internal ankle. 4, The surface of the lower extremity of the
tibia, that unites with one of the tarsal bones to form the ankle-joint.
7, The upper extremity of the tibia, upon which the lower extremity of
the femur rests.]

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Explain fig. 17. Explain fig. 18.

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111. The METATARSAL bones are five in number. They articulate at one
extremity with one range of tarsal bones; at the other extremity, with
the first range of the toe-bones.

[Illustration: Fig. 19. A representation of the upper surface of the
bones of the foot. 1, The surface of the astragulus, where it unites with
the tibia. 2, The body of the astragulus. 3, The calcis, (heel-bone.) 4,
The scaphoid bone. 5, 6, 7, The cuneiform bones. 8, The cuboid. 9, 9, 9,
The metatarsal bones. 10, The first bone of the great toe. 11, The second
bone. 12, 13, 14, Three ranges of bones, forming the small toes]

[Illustration: Fig. 20. A side view of the bones of the foot, showing its
arched form. The arch rests upon the _heel_ behind, and the _ball_ of the
toes in front. 1, The lower part of the tibia. 2, 3, 4, 5, Bones of the
tarsus. 6, The metatarsal bone. 7, 8, The bones of the great toe. These
bones are so united as to secure a great degree of elasticity, or spring.]

_Observation._ The tarsal and metatarsal bones are united so as to
give the foot an arched form, convex above, and concave below. This
structure conduces to the elasticity of the step, and the weight of
the body is transmitted to the ground by the spring of the arch, in a
manner which prevents injury to the numerous organs.

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111. Describe the metatarsal bones. Explain fig. 19. What is
represented by fig. 20? What is said of the arrangement of the bones
of the foot?

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112. The PHALANGES (fig. 19) are composed of fourteen bones; each of
the small toes has three ranges of bones, while the great toe has but
two.

113. The JOINTS form an interesting part of the body. In their
construction, every thing shows the regard that has been paid to the
security and the facility of motion of the parts thus connected
together. They are composed of the extremities of two or more
bones, _Car´ti-lages_, (gristles,) _Syn-o´vi-al_ membrane, and
_Lig´a-ments_.

[Illustration: Fig. 21 The relative position of the bones, cartilages,
and synovial membrane. 1, 1, The extremities of two bones that concur to
form a joint. 2, 2, The cartilages that cover the end of the bones. 3, 3,
3, 3, The synovial membrane which covers the cartilage of both bones, and
is then doubled back from one to the other; it is represented by the
dotted lines.]

[Illustration: Fig. 22. A vertical section of the knee-joint. 1, The
femur. 3, The patella. 5, The tibia. 2, 4, The ligaments of the patella.
6, The cartilage of the tibia 12, The cartilage of the femur. * * * *,
The synovial membrane.]

114. CARTILAGE is a smooth, solid, elastic substance, of a pearly
whiteness, softer than bone. It forms upon the articular surfaces of
the bones a thin incrustation, not more than the sixteenth of an inch
in thickness. Upon convex surfaces it is the thickest in the centre,
and thin toward the circumference; while upon concave surfaces, an
opposite arrangement is presented.

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112. Describe the phalanges. 113-118. _Give the anatomy of the
joints._ 113. What is said of the joints? Of what are the joints
composed? What is illustrated by fig. 21? By fig. 22? 114. Define
cartilage.

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115. The SYNOVIAL MEMBRANE is a thin, membranous layer, which covers
the cartilages, and is thence bent back, or reflected upon the inner
surfaces of the ligaments which surround and enter into the
composition of the joints. This membrane forms a closed sac, like the
membrane that lines an egg-shell.

[Illustration: Fig. 23. The anterior ligaments of the knee-joint. 1, The
tendon of the muscle that extends the leg. 2, The patella. 3, The
anterior ligament of the patella, near its insertion. 4, 4, The synovial
membrane. 5, The internal lateral ligament. 6, The long external lateral
ligament. 7, The anterior and superior ligament that unites the fibula to
the tibia.]

[Illustration: Fig. 24. 2, 3, The ligaments that extend from the clavicle
(1) to the scapula (4.) The ligaments 5, 6, extend from the scapula to
the first bone of the arm.]

116. Beside the synovial membrane, there are numerous smaller sacs,
called _bur´sæ mu-co´sæ_. These are often associated with the
articulation. In structure, they are analogous to synovial membranes,
and secrete a similar fluid.

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115. Describe the synovial membrane. 116. Describe the bursæ mucosæ.
What is represented by fig. 23? By fig. 24?

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117. The LIGAMENTS are composed of numerous straight fibres, collected
together, and arranged into short bands of various breadths, or so
interwoven as to form a broad layer, which completely surrounds the
articular extremities of the bones, and constitutes a capsular
ligament. These connecting bands are white, glistening, and inelastic.
Most of the ligaments are found exterior to the synovial membrane.

118. The bones, cartilages, ligaments, and synovial membrane are
insensible when in health; yet they are supplied with organic nerves,
as well as with arteries, veins, and lymphatics.

_Observation._ The joints of the domestic animals are similar in their
construction to those of man. To illustrate this part of the body, a
fresh joint of the calf or sheep may be used. After divesting the
joints of the skin, the satin-like bands, or ligaments, will be seen
passing from one bone to the other, under which may be observed the
membranous bag, called the capsular ligament. This is very smooth, as
it is lined with the soft synovial membrane, beneath which will be
seen the cartilage, that may be cut with a knife, and under this the
rough extremity of the ends of the bones.

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117. Of what are ligaments composed? What is the appearance of these
bands? Where are they found? 118. With what vessels are the cartilages
and ligaments supplied? How can the structure of the joints be
explained?

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CHAPTER VI.

PHYSIOLOGY OF THE BONES.


119. The bones are the framework of the system. By their solidity and
form, they not only retain every part of the fabric in its proper
shape, but afford a firm surface for the attachment of the muscles and
ligaments. By means of the bones, the human frame presents to the eye
a wonderful piece of mechanism, uniting the most finished symmetry of
form with freedom of motion, and also giving security to many
important organs.

120. To give a clear idea of the relative uses of the bones and
muscles, we will quote the comparison of another, though, as in other
comparisons, there are points of difference. The "bones are to the
body what the masts and spars are to the ship,--they give support and
the power of resistance. The muscles are to the bones what the ropes
are to the masts and spars. The bones are the levers of the system; by
the action of the muscles their relative positions are changed. As the
masts and spars of a vessel must be sufficiently firm to sustain the
action of the ropes, so the bones must possess the same quality to
sustain the action of the muscles in the human body."

121. Some of the bones are designed exclusively for the protection of
the organs which they enclose. Of this number are those that form the
skull, the sockets of the eye, and the cavity of the nose. Others, in
addition to the protection they give to important organs, are useful
in movements of certain kinds. Of this class are the bones of the
spinal column, and ribs. Others are subservient to motion. Of this
class are the upper and lower extremities.

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119-128. _Give the physiology of the bones._ 119. How may the bones be
considered? 120. To what may the bones be compared? 121. Give the
different offices of the bones.

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122. The bones are subject to growth and decay; to removal of old,
useless matter, and the deposit of new particles, as in other tissues.
This has been tested by the following experiment. Some of the inferior
animals were fed with food that contained madder. In a few days, some
of the animals were killed, and their bones exhibited an unusually
reddish appearance. The remainder of the animals were, for a few
weeks, fed on food that contained no coloring principle. When they
were killed, their bones exhibited the usual color of such animals.
The coloring matter, which had been deposited, had been removed by the
action of the lymphatics.

123. The extremities of the bones that concur in forming a joint,
correspond by having their respective configurations reciprocal. They
are, in general, the one convex, and the other concave. In texture
they are porous, and consequently more elastic than if more compact.
These are covered with a cushion of cartilage. The elastic character
of these parts acts as so many springs, in diminishing the jar which
important organs of the system would otherwise receive.

124. The synovial membrane secretes a viscous fluid, which is called
_syn-o´vi-a_. This lubricating fluid of the joints enables the
surfaces of the bones and tendons to move smoothly upon each other,
thus diminishing the friction consequent on their action.

_Observations._ 1st. In this secretion is manifested the skill and
omnipotence of the Great Architect; for no machine of human invention
supplies to itself, by its own operations, the necessary lubricating
fluid. But, in the animal frame, it is supplied in proper quantities,
and applied in the proper place, and at the proper time.

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122. What is said of the change in bones? How was it proved that there
was a constant change in the osseous fabric? 123. What is said of the
extremities of the bones that form a joint? 124. What is synovia? Its
use? What is said of this lubricating fluid?

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2d. In some cases of injury and disease, the synovial fluid is
secreted in large quantities, and distends the sac of the joint. This
affection is called dropsy of the joint, and occurs most frequently in
that of the knee.

125. The function of the ligaments is to connect and bind together the
bones of the system. By them the small bones of the wrist and foot, as
well as the large bones, are as securely fastened as if retained by
clasps of steel. Some of them are situated within the joints, like a
central cord, or pivot, (3, fig. 26.) Some surround it like a hood,
and contain the lubricating synovial fluid, (8, 9, fig. 25,) and some
in the form of bands at the side, (5, 6, fig. 23.)

[Illustration: Fig. 25. 8, 9, The ligaments that extend from the hip-bone
(6) to the femur, (5.)]

[Illustration: Fig. 26. 2, The socket of the hip-joint. 5, The head of
the femur, which is lodged in the socket. 3, The ligament within the
socket.]

126. By the ligaments the lower jaw is bound to the temporal bones,
and the head to the neck. They extend the whole length of the spinal
column, in powerful bands, on the outer surface, between the spinal
bones, and from one spinous process to another. They bind the ribs to
the vertebræ, to the transverse process behind, and to the sternum in
front; and this to the clavicle; and this to the first rib and
scapula; and this last to the humerus.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is the effect when the synovial fluid is secreted in large
quantities? 125. What is the function of the ligaments? 126. Mention
how the bones of the system are connected.

  -=-=-=-=-=-=-=-=-=-=-=-=

127. They also bind the two bones of the fore-arm at the elbow-joint;
and these to the wrist; and these to each other and to those of the
hand; and these last to each other and to those of the fingers and
thumb. In the same manner, they bind the bones of the pelvis together;
and these to the femur; and this to the two bones of the leg and
patella; and so on, to the ankle, foot, and toes, as in the upper
extremities.

[Illustration: Fig. 27. 1, A front view of the lateral ligaments of the
finger-joints. 2, A view of the anterior ligaments (_a_, _b_,) of the
finger-joints. 3, A side view of the lateral ligaments of the finger
joints.]

128. The different joints vary in range of movement, and in complexity
of structure. Some permit motions in all directions, as the shoulder;
some move in two directions, permitting only flexion and extension of
the part, as the elbow; while others have no movement, as the bones of
the head in the adult.

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Explain fig. 27. 128. Describe the variety of movements in the
different joints.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 28. 1, 1, The spinal column. 2, The skull. 3, The
lower jaw. 4, The sternum. 5, The ribs. 6, 6, The cartilages of the ribs.
7, The clavicle. 8, The humerus. 9, The shoulder-joint. 10, The radius.
11, The ulna. 12, The elbow joint. 13, The wrist. 14, The hand. 15, The
haunch-bone. 16, The sacrum. 17, The hip-joint. 18, The thigh-bone. 19,
The patella. 20, The knee-joint. 21, The fibula. 22, The tibia. 23, The
ankle-joint. 24, The foot. 25, 26, The ligaments of the clavicle,
sternum, and ribs. 27, 28, 29, The ligaments of the shoulder, elbow, and
wrist. 30, The large artery of the arm. 31, The ligaments of the
hip-joint. 32, The large blood-vessels of the thigh. 33, The artery of
the leg. 34, 35, 36, The ligaments of the patella, knee, and ankle.]

_Note._ Let the pupil, in form of topics, review the anatomy and
physiology of the bones from fig. 28, or from anatomical outline
plates No. 1 and 2.



CHAPTER VII

HYGIENE OF THE BONES.


129. _The bones increase in size and strength by use, while they are
weakened by inaction._ Exercise favors the deposition of both animal
and earthy matter, by increasing the circulation and nutrition in this
texture. For this reason, the bones of the laborer are dense and
strong, while those who neglect exercise, or are unaccustomed to
manual employment, are deficient in size, and have not a due
proportion of earthy matter to give them the solidity and strength of
the laboring man.

_Observation._ The tendons of the muscles are attached near the
extremities of the bones. Exercise of the muscles increases the action
of the vessels of that part to which the tendons are attached, and
thus increases the nutrition and size of this portion of the bone.
Hence the joints of an industrious mechanic or farmer are larger than
those of an individual who has not pursued manual vocations.

130. _The gelatinous bones of the child are not so well adapted for
labor and severe exercise as those of an adult._ 1st. They are liable
to become distorted. 2d. They are consolidated by the deposition of
earthy material before they are fully and properly developed. If a
young animal, as the colt, be put to severe, continued labor, the
deposition of earthy matter is hastened, and the bones are
consolidated before they attain full growth. Such colts make small and
inferior animals. Similar results follow, if a youth is compelled to
toil unduly before maturity of growth is attained. On the other hand,
moderate and regular labor favors a healthy development and
consolidation of the bones.

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129-148. _Give the hygiene of the bones._ 129. What effect has
exercise upon the bones? What effect has inaction? Why are the joints
of the industrious farmer and mechanic larger than those of a person
unaccustomed to manual employment? 130. Give the first reason why the
bones of the child are not adapted to severe exercise. The second
reason.

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131. _The kind and amount of labor should be adapted to the age,
health, and development of the bones._ Neither the flexible bones of
the child nor the brittle bones of the aged man are adapted, by their
organization, to long-continued, and hard labor. Those of the one bend
too easily, while those of the other fracture too readily. In middle
age, the proportions of animal and earthy matter are, usually, such as
to give the proper degree of flexibility, firmness, and strength for
labor, with little liability to injury.

132. _The imperfectly developed bones of the young child will not bear
long-continued exertions or positions without injury._ Hence the
requisitions of the rigid disciplinarian of schools, are unwise when
he compels his pupils to remain in one position for a long time. He
may have a "quiet school;" but, not unfrequently, by such discipline,
the constitution is impaired, and permanent injury is done to the
pupils.

133. _The lower extremities, in early life, contain but a small
proportion of earthy matter_; they bend when the weight of the body is
thrown upon them for a long time. Hence, the assiduous attempts to
induce children to stand or walk, either naturally or artificially,
when very young, are ill advised, and often productive of serious and
permanent evil. The "bandy" or bow legs are thus produced.

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What effect has moderate, regular labor upon the growing youth? 131.
What remark respecting the kind and amount of labor? At what age are
the bones best fitted for labor? 132. What effect has long-continued
exertions or positions on the bones of a child? What is said of the
requisitions of some teachers, who have the famed "quiet schools"?
133. Why should not the child be induced to stand or walk, either
naturally or artificially, at too early an age?

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134. _The benches or chairs for children in a school-room should be of
such a height as to permit the feet to rest on the floor._ If the
bench is so high as not to permit the feet to rest upon the floor, the
weight of the limbs below the knee may cause the flexible bone of the
thigh to become curved. The child thus seated, is inclined to lean
forward, contracting an injurious and ungraceful habit. Again, when
the feet are not supported, the child soon becomes exhausted,
restless, and unfit for study. In the construction of a school-room,
the benches should be of different heights, so as to be adapted to the
different pupils, and they should also have appropriate backs.

[Illustration: Fig. 29. The position assumed when the seat is of proper
height, and the feet supported.]

[Illustration: Fig. 30. The position a child naturally assumes when the
seat is so high that the feet are not supported.]

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134. What is said of the benches or chairs in a school-room? What is
represented by fig. 29? By fig. 30? What is the effect when the lower
limbs are not supported?

  -=-=-=-=-=-=-=-=-=-=-=-=

135. _Compression of the chest should be avoided._ In children, and
also in adults, the ribs are very flexible, and a small amount of
pressure will increase their curvature, particularly at the lower part
of the chest, and thus lessen the size of this cavity. The lower ribs
are united to the breast-bone, by long, yielding cartilages, and
compression may not only contract the chest, but an unseemly and
painful ridge may be produced, by the bending of the cartilages, on
one or both sides of the sternum.

[Illustration: Fig. 31. A natural and well-proportioned chest.]

[Illustration: Fig. 32. A chest fashionably deformed.]

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135. Why should compression of the chest be avoided? What is
represented by fig. 31? By fig. 32?

  -=-=-=-=-=-=-=-=-=-=-=-=

136. Again, the cartilages on one side may be bent outward, while
those on the opposite side are bent inward, thus forming a depression
parallel with the sternum. In some instances, the anterior extremity
of the lower ribs on each side are brought nearly or quite together.
In these instances, the movable extremities of the ribs are drawn down
toward the haunch-bones, while the space between the ribs is lessened.
All this may be effected by tight or "snug" clothing. Therefore the
apparel of a child should be loose, and supported over the shoulders,
to avoid the before-mentioned evils. The same may be said of the
clothing for adults.

137. _The erect position in sitting and standing should be assiduously
observed._ The spinal column, in its natural position, curves from
front to back, but not from side to side The admirable arrangement of
the bones, alternating with cartilages, permits a great variety of
motions and positions; and when the spine is inclined to either side,
the elasticity of its cartilages tends to restore it to its natural
position. For this reason we may incline the spinal column in any
direction for a short time, without danger of permanent curvature, if,
afterward, the erect position is assumed.[4]

   [4] Compare 1, 1, Fig. 28, with 2, 2, 2, Fig. 48.

138. But if a stooping position, or a lateral curved posture, is
continued for a long time, the spinal column does not easily recover
its proper position, for the compressed edges of the cartilages lose
their power of reaction, and finally one side of the cartilage becomes
thinned, while the other is thickened; and these wedge-shaped
cartilages produce a permanent curvature of the spinal column. In a
similar way, the student, seamstress, artisan, and mechanic acquire a
stooping position, and become round shouldered, by inclining forward
to bring their books or work nearer the eyes.

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136. May simply "snug" clothing compress the cartilages? How should
the apparel of a child be worn? 137. In what direction does the spinal
column, in its natural position, curve? What restores it to its
natural position when curved laterally? 138. What is the effect if a
lateral curved position of the spinal column is continued for a long
time? 139. When one shoulder is elevated for a long time, what is the
effect upon the spinal column?

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139. Pupils, while writing, drawing, and sometimes while studying,
frequently incline the spinal column to one side, in order to
accommodate themselves to the desks at which they are seated. Often,
these are higher than the elbow as it hangs from the shoulder while at
rest. This attitude elevates one shoulder while it depresses the
other; consequently, the upper part of the spinal column is inclined
toward the elevated shoulder, and the lower part is curved in the
opposite direction, giving the form of the letter _S_ to the
supporting column of the body.

[Illustration: Fig. 33. The table is of proper height, the position is
correct, and the spinal column, 1, 1, is straight, while the shoulders
are of equal height.]

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What does fig. 33 represent?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Experiment._ Let a pupil be placed at a desk or table with one elbow
raised, as is frequently seen while writing, or at study, and observe
the condition of the shoulder and spinal column in this position.
Place another pupil at a table no higher than the elbow when it hangs
by the side while sitting, and observe the appearance of the shoulders
and spinal column. By a comparison of the two attitudes, the preceding
remarks will be comprehended and appreciated.

[Illustration: Fig. 34. The table is too high, and the position is
oblique and improper. The right shoulder is seen higher than the left,
while the spinal column, 1, 1, exhibits three curves.]

140. One shoulder may be elevated, and no injurious results follow,
provided care is taken not to keep it in the raised position too long,
or if the opposite shoulder is elevated for the same period of time.
The right shoulder projects more frequently than the left. This arises
from the greater use of the right hand with the shoulder elevated, and
not unfrequently the oblique positions assumed in performing the daily
vocations of life. With proper care, and by calling into action the
left shoulder, this deformity can be prevented.

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What experiment is mentioned? What does fig. 34 represent? 140. How
can one shoulder be elevated and no injurious results follow?

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[Illustration: Fig. 35. A representation of a deformed trunk.]

141. The loss of symmetry and diminution of height from deformed
spines are minor considerations, compared with the distortions that
the chest experiences, thereby impairing respiration and inducing
diseases of the heart and lungs. The invasion of the functions of
these two important organs lessens the vitality of the whole system,
and causes general ill health. Again, the curvature of the spinal
column is frequently attended by irritation and disease of the spinal
cord.

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Why does the right shoulder project more frequently than the left? How
can this deformity be prevented? 141. What is said of deformed spinal
columns?

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142. Eminent physicians, both in this country and France state that
not more than one female in ten, who has been fashionably educated, is
free from deformities of the shoulder or spinal column. Teachers, as
well as mothers, should notice the positions of the child in
performing the tasks allotted to it, whether studying or pursuing any
employment. The feebler the organization of the child, the more
frequently should there be a change of position.

143. When a slight projection of the shoulder, with a curvature of the
spine, exists, it can be improved by walking with a book, or something
heavier, upon the head; to balance which, the spinal column must be
nearly erect. Those people that carry burdens upon their heads seldom
have crooked spines.

_Observation._ Persons from the North, in travelling through the
Southern States, are surprised to see the heavy burdens that the
porters carry on their heads. It is not unusual to see them walking at
a rapid pace, with one or two trunks, weighing fifty or eighty pounds
each, upon their heads. Occasionally, we meet an itinerant toy-man,
with his tray of fragile merchandise upon his head, walking with as
much apparent security, as though his toys, or images, were in his
hands. This is the easiest method of carrying burdens, because the
position of the head and spinal column is erect.

144. _If the animal and earthy matter of the bones is not deposited in
proper proportions, they are deficient in strength._ If the gelatin
predominates, the bones are weak, and become distorted. When
nutrition is defective in the cylindrical bones, the heads are
generally enlarged, and the shafts crooked; if in the spinal column,
it may be curved; or in the cranium, it may be enlarged. This disease
is familiarly known by the name of rickets. It is most common among
these who have poor and insufficient food, live in dark, damp rooms,
and breathe a vitiated air. The prevention and remedies for this
disease are cleanliness, regular exercise, pure air, and nutritious
food.

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142. What statement by eminent physicians respecting deformities of
the spine? What caution to teachers and mothers? 143. Why should we
stand and sit erect? How may slight deformities of the spine be
prevented? What is frequently noticed in travelling South? 144. What
is the effect upon the bones when the gelatin preponderates?

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145. When a bone is broken, some days elapse before the substance that
reunites it is thrown out from the blood. In young persons, it may be
secreted during the second or third week, and in individuals advanced
in life, usually during the third and fourth week. When the bone is
uniting, during the second, third, or fourth week, the attention of a
surgeon is more needed than during the first week. At this time, the
ends of the bone should be placed together with accuracy, which
requires the careful application of proper dressing. After the bones
have united, it will take some weeks to consolidate the uniting
material and render the "callus," or union, firm. During this time,
the limb should be used with care.

_Observation._ When a bone is fractured, a surgeon is immediately
called, and the bone is "set." While the limb remains swelled and
painful, the surgeon is required to attend and keep the dressings
(bandages and splints) on. When the swelling has abated, and the pain
subsided, frequently the patient intimates to the surgeon that his
services can be dispensed with, as the "limb is doing well." This is
the most important period, as the bone is uniting, and, unless the
ends are nicely adjusted, the dressing properly applied, the person
will find, on recovery, a shortened and crooked limb. The surgeon is
then censured, when he is not blamable.

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What is one cause of rickets? What are the prevention and remedies for
this disease? 145. Does the time vary when the reuniting substance of
the bone is secreted from the blood? When is the surgeon's care most
needed? Why?

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146. It is seldom that a bone is displaced without injury to the
connecting ligaments and membranes. When these connecting bands are
lacerated, pain, swelling, and other symptoms indicating inflammation
succeed, which should be removed by proper treatment, directed by a
surgical adviser.

147. In sprains, but few, if any, of the fibres of the connecting
ligaments are lacerated; but they are unduly strained and twisted,
which occasions acute pain at the time of the injury. This is followed
by inflammation and weakness of the joints. The treatment of these
injuries is similar to that of a dislocated bone after its reduction.
The most important item in the treatment during the few first days, is
rest.

148. In persons of scrofulous constitutions, and those in whom the
system is enfeebled by disease, white swellings and other chronic
diseases of the joints frequently succeed sprains. Such persons cannot
be too assiduous in adopting a proper and early treatment of injured
joints.

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146. What parts are injured in the displacement of a bone? 147. What
causes the acute pain in sprains? What is a good remedy for this kind
of injury? 148. What caution to persons of scrofulous constitutions?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER VIII

THE MUSCLES.


149. All the great motions of the body are caused by the movement of
some of the bones which form the framework of the system; but these,
independently of themselves, have not the power of motion, and only
change their position through the action of other organs attached to
them, which, by contracting, draw the bones after them. In some of the
slight movements, as the winking of the eye, no bones are displaced.
These moving, contracting organs are the _Mus´cles_, (lean meat.)


ANATOMY OF THE MUSCLES.

150. The MUSCLES, by their size and number, constitute the great bulk
of the body, upon which they bestow form and symmetry. In the limbs,
they are situated around the bones, which they invest and defend,
while they form, to some of the joints, their principal protection. In
the trunk, they are spread out to enclose cavities, and constitute a
defensive wall, capable of yielding to internal pressure, and
reassuming its original state.

151. In structure, a muscle is composed of _fas-cic´u-li_ (bundles of
fibres) of variable size. These are enclosed in a cellular membranous
investment, or sheath. Every bundle composed of a number of small
fibres, and each fibre consists of a number of filaments, each of
which is enclosed in a delicate sheath. Toward the extremity of the
organ the muscular fibre ceases, and the cellular structure becomes
aggregated, and so modified as to constitute _ten´dons_, (cords,) by
which the muscle is tied to the surface of the bone. The union is so
firm, that, under extreme violence, the bone will sooner break than
permit the tendon to separate from its attachment. In some situations,
there is an expansion of the tendon, in the manner of a membrane,
called _Ap-o-neu-ro´sis_, or _Fas´ci-a_.

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149. How are all the motions of the body produced? What are these
motor organs called? 150-160. _Give the anatomy of the muscles._ 150.
What is said of the muscles? 151. Give their structure.

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_Observation._ The pupil can examine a piece of boiled beef, or the
leg of a fowl, and see the structure of the fibres and tendons of a
muscle.

[Illustration: Fig. 36. 1, A representation of the direction and
arrangement of the fibres in a fusiform, or spindle-shaped muscle. 2, In
a radiated muscle. 3, In a penniform muscle. 4, In a bipenniform muscle.
_t_, _t_, The tendons of a muscle.]

152. Muscles present various modifications in the arrangement of their
fibres, as relates to their tendinous structure. Sometimes they are
completely longitudinal, and terminate, at each extremity, in a
tendon, the entire muscle being spindle-shaped. In other situations,
they are disposed like the rays of a fan, converging to a tendinous
point, and constituting a _ra´di-ate_ muscle. Again they are
_pen´ni-form_, converging, like the plumes of a pen, to one side of a
tendon, which runs the whole length of the muscle; or they are
_bi-pen´ni-form_, converging to both sides of the tendon.

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How are tendons or cords formed? What is the expansion of a tendon
called? How can the structure of muscles and their fibres be shown?
What does fig. 36 represent? 152. Give the different arrangements of
muscular fibres.

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153. In the description of a muscle, its attachments are expressed by
the terms "origin" and "insertion." The term _origin_ is generally
applied to the more fixed or central attachment, or to the point
toward which motion is directed; while _insertion_ is assigned to the
more movable point, or to that most distant from the centre. The
middle, fleshy portion is called the "belly," or "swell." The color of
a muscle is red in warm-blooded fish and animals; and each fibre is
supplied with arteries, veins, lymphatics, and both sensitive and
motor nervous filaments.

154. The FASCIA is of various extent and thickness, distributed
through the different regions of the body, for the purpose of
investing and protecting the softer and more delicate organs. An
instance is seen in the membrane which envelopes a leg of beef, and
which is observed on the edges of the slices when it is cut for
broiling. When freshly exposed, it is brilliant in appearance, tough,
and inelastic. In the limbs it forms distinct sheaths to all the
muscles.

155. This tendinous membrane assists the muscles in their action, by
keeping up a tonic pressure on their surface. It aids materially in
the circulation of the fluids, in opposition to the laws of gravity.
In the palm of the hand and sole of the foot, it is a powerful
protection to the structures that enter into the formation of these
parts. In all parts of the system, the separate muscles are not only
invested by fascia, but they are arranged in layers, one over
another. The sheath of each muscle is loosely connected with another,
by the cellular membrane.

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153. What is meant by the origin of a muscle? The insertion? The
swell? What is the color of muscles? With what is each muscular fibre
supplied? 154. What is said of fascia? What is its appearance when
freshly exposed? 155. What effect has it on the muscles? Give other
uses of the fascia.

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156. The interstices between the different muscles are filled with
adipose matter, or fat. This is sometimes called the packing of the
system. To the presence of this tissue, youth are indebted for the
roundness and beauty of their limbs.

[Illustration: Fig. 37. A transverse section of the neck. The separate
muscles, as they are arranged in layers, with their investing fasciæ, are
beautifully represented. As the system is symmetrical, figures are placed
only on one side. In the trunk the muscles are arranged in layers,
surrounded by fasciæ, as in the neck. The same is true of the muscles of
the upper and lower limbs.

12, The trachea, (windpipe.) 13, The oesophagus, (gullet.) 14, The
carotid artery and jugular vein. 28, One of the bones of the spinal
column. The figures that are placed in the white spaces represent some of
the fasciæ; the other figures indicate muscles.]

157. The muscles may be arranged, in conformity with the general
division of the body, into four parts: 1st. Those of the _Head_
and _Neck_. 2d. Those of the _Trunk_. 3d. Those of the _Upper
Extremities_. 4th. Those of the _Lower Extremities_.

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156. Give a reason why the limbs of youth are rounder than those of
the aged. Describe fig. 37.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 38. The superficial layer of muscles on the face and
neck. 1, 1, The occipito-frontalis muscle. 2, The orbicularis
palpebrarum. 6, The levator labii superioris 7, The levator anguli oris.
8, The zygomaticus minor. 9, The zygomaticus major 10, The masseter. 11,
The depressor labii superioris. 13, The orbicularis oris. 15, The
depressor anguli oris. 16, The depressor labii inferioris. 18, The
sterno-hyoideus. 19, The platysma-myodes. 20, The superior belly of the
omo-hyoideus. 21, The sterno-cleido mastoideus. 20, The scalenus medius.
23, The inferior belly of the omo-hyoideus. 24, The trapezius.[5]

_Practical Explanation._ The muscle 1, 1, elevates the eyebrows. The
muscle 2 closes the eye. The muscle 6 elevates the upper lip. The muscles
7, 8, 9, elevate the angle of the mouth. The muscle 10 brings the teeth
together when eating. The muscle 11 depresses the upper lip. The muscle
13 closes the mouth. The muscle 15 depresses the angle of the mouth. The
muscle 16 draws down the lower lip. The muscles 18, 19, 20, 23, depress
the lower jaw and larynx and elevate the sternum. The muscle 21, when
both sides contract, draws the head forward, or elevates the sternum;
when only one contracts, the face is turned one side toward the opposite
shoulder. The muscles 18, 19, 20, 21, 22, 23, 24, aid in respiration.]

   [5] In the plates illustrating the muscular system, the names of such
       muscles are given as are referred to in the paragraph
       "Practical Explanation." These names need not be committed to
       memory. If a pupil wishes to acquire a knowledge of the general
       attachment of the muscles represented in the plates, he can do
       so by _comparing_ the muscular plate with that of the skeleton,
       (fig. 28.)

_Observation._ When we are sick, and cannot take food, the body is
sustained by absorption of the fat. The removal of it into the blood
causes the sunken cheek, hollow eye, and prominent appearance of the
bones after a severe illness.

158. The number of muscles in the human body is more than five
hundred; in general, they form about the skeleton two layers, and are
distinguished into superficial and deep-seated muscles. Some of the
muscles are voluntary in their motions, or act under the government of
the will, as those which move the fingers, limbs, and trunk; while
others are involuntary, or act under the impression of their proper
stimulants, without the control of the individual, as the heart.

_Observations._ 1st. The abdominal muscles are expiratory, and the
chief agents for expelling the residuum from the rectum, the bile from
the gall bladder, the contents of the stomach and bowels when
vomiting, and the mucus and irritating substances from the bronchial
tubes, trachea, and nasal passages by coughing and sneezing. To
produce these effects they all act together. Their violent and
continued action sometimes produces hernia, and, when spasmodic, may
occasion ruptures of the different organs.

2d. The contraction and relaxation of the abdominal muscles and
diaphragm stimulate the stomach, liver, and intestines to a healthy
action, and are subservient to the digestive powers. If the
contractility of their muscular fibres is destroyed or impaired, the
tone of the digestive apparatus will be diminished, as in indigestion
and costiveness. This is frequently attended by a displacement of
those organs, as they generally gravitate towards the lower portion of
the abdominal cavity, when the sustaining muscles lose their tone and
become relaxed.

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What causes the hollow eye and sunken cheek after a severe sickness?
158. How many muscles in the human system? Into how many layers are
they arranged? What is a voluntary muscle? Give examples. What is an
involuntary muscle? Mention examples. Give observation 1st, respecting
the use of the abdominal muscles? Observation 2d.

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[Illustration: Fig. 39. A front view of the muscles of the trunk. On the
left side the superficial layer is seen; on the right, the deep layer. 1,
The pectoralis major muscle. 2, The deltoid muscle. 6, The pectoralis
minor muscle. 9, The coracoid process of the scapula. 11, The external
intercostal muscle. 12, The external oblique muscle 13, Its aponeurosis.
16, The rectus muscle of the right side. 18, The internal oblique muscle.

_Practical Explanation._ The muscle 1 draws the arm by the side, and
across the chest, and likewise draws the scapula forward. The muscle 2
elevates the arm. The muscle 6 elevates the ribs when the scapula is
fixed, or draws the scapula forward and downward when the ribs are fixed.
The muscles 12, 16, 18, bend the body forward or elevate the hips when
the muscles of both sides act. They likewise depress the rib in
expiration. When the muscles on only one side act, the body is twisted to
the same side.]

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Explain fig. 39. Give the function of some of the most prominent
muscles, from this figure.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 40. A lateral view of the muscles of the trunk. 3,
The upper part of the external oblique muscle. 4, Two of the external
intercostal muscles. 5, Two of the internal intercostals. 6, The
transversalis muscle. 7, Its posterior aponeurosis. 8, Its anterior
aponeurosis. 11, The right rectus muscle. 13, The crest of the ilium, or
haunch-bone.

_Practical Explanation._ The rectus muscle, 11, bends the thorax upon the
abdomen when the lower extremity of the muscle is the fixed point; but
when the upper extremity is the fixed point, the effect is to bring
forward and raise the pelvis and lower extremities. They likewise depress
the ribs in respiration. The transverse muscle, 6, 7, 8, lessens the
cavity of the abdomen, and presses the intestines; stomach, and liver
upward, against the diaphragm, in expiration.]

3d. The region of the back, in consequence of its extent, is common to
the neck, the upper extremities, and the abdomen. The muscles of which
it is composed are numerous, and are arranged in six layers.

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What is represented by fig. 40? Give the function of some of the
muscles represented by this figure.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 41 The first, second, and part of the third layer of
muscles of the back. The first layer is shown on the right, and the
second on the left side. 1, The trapezius muscle. 2, The spinous
processes of the vertebræ. 3, The acromion process and spine of the
scapula. 4, The latissimus dorsi muscle. 5, The deltoid muscle. 7, The
external oblique muscle. 8, The gluteus medius muscle. 9, The gluteus
maximus muscle, 11, 12, The rhomboideus major and minor muscles. 15, The
vertebral aponeurosis. 16, The serratus posticus inferior muscle. 22, The
serratus magnus muscle. 23, The internal oblique muscle.

_Practical Explanation._ The muscles 1, 11, 12, draw the scapula back
toward the spine. The muscles 11, 12, draw the scapula upward toward the
head, and slightly backward. The muscle 4 draws the arm by the side, and
backward, The muscle 5 elevates the arm. The muscles 8, 9, extend the
thigh on the body. The muscle 1 draws the head back and elevates the
chin. The muscle 16 depresses the ribs in expiration. The muscle 22
elevates the ribs in inspiration.]

159. The diaphragm, or midriff, is the muscular division between the
thorax and the abdomen. It is penetrated by the oesophagus on its way
to the stomach, by the aorta conveying blood toward the lower
extremity, and by the ascending vena cava, or vein, on its way to the
heart.

[Illustration: Fig. 42. A representation of the under, or abdominal side
of the diaphragm. 1, 2, 3, 4, The portion which is attached to the margin
of the ribs. 8, 10, The two fleshy pillars of the diaphragm, which are
attached to the third and fourth lumbar vertebræ. 9, The spinal column.
11, The opening for the passage of the aorta. 12, The opening for the
oesophagus. 13, The opening for the ascending vena cava, or vein.]

_Observation._ The diaphragm may be compared to an inverted basin, its
bottom being turned upward into the thorax, while its edge corresponds
with the outline of the edges of the lower ribs and sternum. Its
concavity is directed toward the abdomen, and thus, this cavity is
very much enlarged at the expense of that of the chest, which is
diminished to an equal extent.

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159. Describe the diaphragm. What vessels penetrate this muscular
septum?

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160. "The motions of the fingers do not merely result from the action
of the large muscles which lie on the fore-arm, these being concerned
more especially in the stronger actions of the hands. The finer and
more delicate movements of the fingers are performed by small muscles
situated in the palm and between the bones of the hand, and by which
the fingers are expanded and moved in all directions with wonderful
rapidity."

[Illustration: Fig. 43. A front view of the superficial layer of muscles
of the fore-arm. 5, The flexor carpi radialis muscle. 6, The palmaris
longus muscle. 7, One of the fasciculi of the flexor sublimis digitorum
muscle, (the rest of the muscle is seen beneath the tendons of the
pintails longus.) 8, The flexor carpi ulnaris muscle. 9, The palmar
fascia. 11, The abductor pollicis muscle. 12, One portion of the flexor
orevis pollicis muscle. 13, The supinator longus muscle. 14, The extensor
ossis metacarpi, and extensor primi internodii pollicis muscles, curving
around the lower border of the fore-arm. 15, The anterior portion of the
annular ligament, which binds the tendons in their places.

_Practical Explanation._ The muscles 5, 6, 8, bend the wrist on the bones
of the fore-arm. The muscle 7 bends the second range of finger-bones on
the first. The muscle 11 draws the thumb from the fingers. The muscle 12
flexes the thumb. The muscle 13 turns the palm of the hand upward. The
muscles 8, 13, 14, move the hand laterally.]

[Illustration: Fig. 44. A back view of the superficial layer of muscles
of the fore-arm. 5, The extensor carpi radialis longior muscle. 6, The
extensor carpi radialis brevior muscle. 7, The tendons of insertion of
these two muscles. 8, The extensor communis digitorum muscle. 9, The
extensor minimi dlgiti muscle. 10, The extensor carpi ulnaris muscle. 13,
The extensor ossis metacarpi and extensor primi internodii muscles, lying
together. 14, The extensor secundi internodii muscle; its tendon is seen
crossing the two tendons of the extensor carpi radialis longior and
brevior muscles. 15, The posterior annular ligament. The tendons of the
common extensor muscle of the fingers are seen on the back of the hand,
and their mode of distribution on the back of the fingers.

_Practical Explanation._ The muscles 5, 6, 10, extend the wrist on the
fore-arm. The muscle 8 extends the fingers. The muscle 9 extends the
little finger. The muscles 13 extend the metacarpal bone of the thumb,
and its first phalanx. The muscle 14 extends the last bone of the thumb.
The muscles 10, 13, 14, move the hand laterally.]

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160. Where are the muscles situated that effect the larger movements
of the hand? That perform the delicate movements of the fingers? Give
the use of some of the muscles represented by fig. 43. Those
represented by fig. 44.

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CHAPTER IX.

PHYSIOLOGY OF THE MUSCLES.


161. The muscles exercise great influence upon the system. It is by
their contraction that we are enabled to pursue different employments.
By their action the farmer cultivates his fields, the mechanic wields
his tools, the sportsman pursues his game, the orator gives utterance
to his thoughts, the lady sweeps the keys of the piano, and the young
are whirled in the mazy dance. As the muscles bear so intimate a
relation to the pleasures and employments of man, a knowledge of the
laws by which their action is governed, and the conditions upon which
their health depends, should be possessed by all.

162. The peculiar characteristic of muscular fibres is _contractility_,
or the power of shortening their substance on the application of
stimuli, and again relaxing when the stimulus is withdrawn. This is
illustrated in the most common movements of life. Call into action the
muscles that elevate the arm, by the influence of the _will_, or mind,
(the common stimulus of the muscles,) and the hand and arm are
raised; withdraw this influence by a simple effort of the will, and
the muscles, before rigid and tense, become relaxed and yielding.

163. The contractile effect of the muscles, in producing the varied
movements of the system, may be seen in the bending of the elbow.
The tendon of one extremity of the muscle is attached to the
shoulder-bone, which acts as a fixed point; the tendon of the
other extremity is attached to one of the bones of the fore-arm. When
the swell of the muscle contracts, or shortens, its two extremities
approach nearer each other, and by the approximation of the
terminal extremities of the muscle, the joint at the elbow bends.
On this principle, all the joints of the system are moved. This is
illustrated by fig. 45.

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161-172. _Give the physiology of the muscles._ 161. What are some of
the influences exerted by the muscles on the system? 162. What is
peculiar to muscular fibres? How is this illustrated? 163. Explain how
the movements of the system are effected by the contraction of the
muscles.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 45. A representation of the manner in which all of
the joints of the body are moved. 1, The bone of the arm above the elbow.
2, One of the bones below the elbow. 3, The muscle that bends the elbow.
This muscle is united, by a tendon, to the bone below the elbow, (4,) at
the other extremity, to the bone above the elbow, (5,) 6, The muscle that
extends the elbow. 7, Its attachment to the point of the elbow. 8, A
weight in the hand to be raised. The central part of the muscle 3
contracts, and its two ends are brought nearer together. The bones below
the elbow are brought to the lines shown by 9, 10, 11. The weight is
raised in the direction of the curved line. When the muscle 6 contracts,
the muscle 3 relaxes and the fore-arm is extended.]

_Experiments._ 1st. Clasp the arm midway between the shoulder and
elbow, with the thumb and fingers of the opposite hand. When the arm
is bent, the inside muscle will become hard and prominent, and its
tendon at the elbow rigid, while the muscle on the opposite side will
become flaccid. Extend the arm at the elbow, and the outside muscle
will swell and become firm, while the inside muscle and its tendon at
the elbow will be relaxed.

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Explain fig. 45. Give experiment 1st.

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. Clasp the fore-arm about three inches below the elbow, then open
and shut the fingers rapidly, and the swelling and relaxation of the
muscles on the opposite sides of the arms, alternating with each
other, will be felt, corresponding with the movement of the fingers.
While the fingers are bending, the inside muscles swell, and the
outside ones become flaccid; and, while the fingers are extending, the
inside muscles relax, and the outside ones swell. The alternate
swelling and relaxation of antagonist muscles may be felt in the
different movements of the limbs.

164. Each fibre of the several muscles receives from the brain, through
the nervous filament appropriated to it, a certain influence, called
nervous fluid, or stimulus. It is this that induces contraction, while
the suspension of this stimulus causes relaxation of the fibres. By
this arrangement, the action of the muscular system, both as regards
duration and power, is, to a limited extent, under the control of the
mind. The more perfect the control, the better the education of the
muscular system; as is seen in the graceful, effective, and
well-educated movements of musicians, dancers, skaters, &c.

165. The length of time which a muscle may remain contracted, varies.
The duration of the contraction of the voluntary muscles, in some
measure, is in an inverse ratio to its force. If a muscle has
contracted with violence, as when great effort is made to raise a
heavy weight, relaxation will follow sooner than when the contraction
has been less powerful, as in raising light bodies.

166. The velocity of the muscular contraction depends on the will.
Many of the voluntary muscles in man contract with great rapidity, so
that he is enabled to utter distinctly fifteen hundred letters in a
minute; the pronunciation of each letter requiring both relaxation and
contraction of the same muscle, thus making three thousand actions in
one minute. But the contraction of the muscles of some of the inferior
animals surpasses in rapidity those of man. The race-horse, it is
said, has run a mile in a minute; and many birds of prey will probably
pass not less than a thousand miles daily.

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Give experiment 2d. 164. With what is each muscular fibre supplied?
What effect has this stimulus on the muscles? 165. how long does a
voluntary muscle remain contracted? 166. On what is the velocity of
muscular contraction dependent? How many letters may be pronounced in
a minute?

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167. The functions of the involuntary muscles are necessary the
digestion of food, the absorption and circulation of the nutritive
fluids. They could not be trusted with safety to the control of the
will, lest the passions or the indiscretions of the person should
continually avert those operations so necessary to health, and even to
life. The Divine Builder of this complicated machine has wisely
ordered that the muscles upon which these motions depend, shall act
under the impression of their proper stimulants, without the control
of the individual.

168. Again, there are certain operations which could not be safely
intrusted to the absolute government of the voluntary muscles, or
entirely removed from their control. Thus life can be supported only a
few minutes without breathing; but it would be impossible to perform
the daily vocations of life if we were compelled to breathe at all
times, or at perfectly regular intervals.

169. It has been observed that, among men of the same size, a wide
difference exists in their strength and activity--qualities which
depend upon the size and number of the nerves, the size and activity
of the brain, and the education, or training of the muscles. Men
having large nerves leading to the muscles, with the brain active,
and muscles well trained will perform feats of strength and agility,
that other men, of the same size, cannot effect. Rope-dancers,
harlequins, and other performers of feats, are persons thus
constituted.

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How many contractions and relaxations of the same muscle? What is said
of the rapidity of muscular contractions in other animals? 167. When
are the involuntary muscles called into action? Why would it not have
been safe to trust these important operations to the exclusive control
of the will? 168. Give an instance where some of the muscles act under
the government of the will, conjoined with those that are involuntary.
169. On what does the difference in muscular activity and strength
depend?

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170. Persons with small muscles, and largely developed nervous
systems, will sometimes exhibit very great muscular power for a time;
but it will not be of long continuance, unless the brain is
functionally diseased, as in hysteria, delirium of fever, insanity,
&c. Men of large muscles and small nerves can never perform feats of
great strength; but they have the power of endurance, and are better
capacitated for continued labor. Thus we cannot judge of the ability
of persons to make exertions and continue them, by their stature
alone. Strength, and the power of endurance, are the result of a
combination of well-developed muscles, large nerves, and a full-sized,
healthy, and active brain.

_Observation._ The muscles of fishes are large, and the nerves
distributed to them, comparatively small. The muscles of birds are
small, but their fibres are very compact. The nerves appropriated to
the muscles that are called into action in flying, are large as well
as numerous.

171. The contractile portion of a muscle is, in general, at a distance
from the part to be moved. Thus the principal muscles that move the
fingers are situated upon the forearm; and when the limb is nearly or
quite extended, the angle formed by the part to be moved and the
contractile muscles is small. Again, the attachment of the muscles to
the part to be moved is near the joint that forms the fulcrum, (fig.
45.) By these arrangements there is a loss of power; but we are
compensated for this disadvantage by increased celerity of movement,
beauty of form, and adaptation of the limbs to the varied pursuits of
man.

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170. What is said of those persons who have small muscles and largely
developed nervous systems? Of those who have large muscles and small
nerves? Upon what do strength and the power of endurance depend? 171.
Why is there a loss of power in the action of the muscles?

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_Illustration._ The muscle that bends the elbow acts at disadvantage,
and this is greatest when the arm is nearly or quite extended, as the
angle of action is then least. This disadvantage is further increased
by the attachment of the motive muscles near the joint.

172. The number of muscles which are called into action in the
movements of the different joints, varies. The hinge-joints, as the
elbow, have two sets of muscles--one to bend the joint, the other to
extend it. The ball and socket joints, as the shoulder, are not
limited to mere flexion and extension. No joint in the system has the
range of movement that is possessed by that of the shoulder. By the
action of the muscles attached to the arm, it is not only carried
upward and forward, but forward and backward. Hence the arm may be
moved at any angle, by a combined action of its muscles.

_Observation._ "Could we behold properly the muscular fibres in
operation, nothing, as a mere mechanical exhibition, can be conceived
more superb than the intricate and combined actions that must take
place during our most common movements. Look at a person running or
leaping, or watch the motions of the eye. How rapid, how delicate, how
complicated, and yet how accurate, are the motions required! Think of
the endurance of such a muscle as the heart, that can contract, with a
force equal to sixty pounds, seventy-five times every minute, for
eighty years together, without being weary."

_Note._ It would be a profitable exercise for pupils to press their
fingers upon prominent muscles, and, at the same time, vigorously
contract them, not only to learn their situations, but their use; as
the one that bends the arm, 14, fig. 46.

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How is this illustrated? 172. Do all joints require the same number of
muscles, when called into action? How many are called into action in
the movement of the elbow? What is their office? What is said of the
movement of the ball and socket joint?

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[Illustration: Fig. 46. An anterior view of the muscles of the body. 1.
The frontal swell of the occipito-frontalis. 2, The orbicularis
palpebrarum. 3, The levator labli superioris. 4, The zygomaticus major.
5, The zygomaticus minor. 6, The masseter. 7, The orbicularis oris. 8,
The depressor labli inferioris. 9. The platysma myodes. 10, The deltoid.
11, The pectoralis major. 12, The latissimus dorsi. 14, The biceps flexor
cubiti. 15, The triceps extensor cubiti. 16, The supinator radii longus.
18, The flexor carpi radialis longior. 19, The flexor communis digitorum.
20, The annular ligament. 21, The palmar fascia. 22, The obliquus
externus abdominis. 26, The psoas magnus. 27, The adductor longus. 28,
The sartorius. 29, The rectus femoris. 30, The vastus externus. 31, The
vastus internus. 32, The tendon patellæ. 33, The gastrocnemius. 34, The
tibialis anticus. 36, The tendons of the extensor digitorum communis.]

[Illustration: Fig. 47. A posterior view of the muscles of the body. 3,
The complexus. 4, The splenius. 5, The masseter. 6, The sterno-cleido
mastoideus. 7, The trapezius. 8, The deltoid. 10, The triceps extensor.
13, The tendinous portion of the triceps. 14, The anterior edge of the
triceps. 15, The supinator radii longus. 17, The extensor communis
digitorum. 18, The extensor ossis metacarpi pollicis. 19, The tendons of
the extensor communis digitorum. 20, The olecranon process of the ulna
and insertion of the triceps. 21, The extensor carpi ulnaris. 22, The
extensor communis digitorum. 24, The latissimus dorsi. 25, Its tendinous
origin. 26, The obliquus externus. 27, The gluteus medius. 28, The
gluteus magnus. 29, The biceps flexor cruris. 30, The semi-tendinosus.
31, 32, The gastrocnemius. 33, The tendo Achillis.

_Practical Explanation._ The muscle 1, fig. 46, by its contraction,
raises the eyebrows. The muscle 2, fig. 46, closes the eyelids. The
muscle 3, fig. 46, elevates the upper lip. The muscles 4, 5, fig. 46,
elevate the angles of the mouth. The muscles 6, fig. 46, and 5, fig. 47,
bring the teeth together. The muscle 7, fig. 46, closes the mouth. The
muscle 8, fig. 46, depresses the lower lip. The muscles 9, fig. 46, and
6, fig. 47, bend the neck forward. The muscles 3, 4, fig. 47, elevate the
head and chin. The muscle 22, fig. 46, bends the body forward, and draws
the ribs downward. The muscle 11, fig. 46, brings the shoulder forward.
The muscle 7, fig. 47, draws the shoulder back. The muscles 10, fig. 46,
and 8, fig. 47, elevate the arm. The muscles 11, fig. 46, and 24, fig.
47, bring the arm to the side. The muscle 14, fig. 46, bends the arm at
the elbow. The muscle 10, fig. 47, extends the arm at the elbow. The
muscles 16, 18, fig. 46, bend the wrist and fingers. The muscle 19 bends
the fingers. The muscles 18, 21, 23, fig. 47, extend the wrist. The
muscle 23, fig. 47, extends the fingers. The muscles 26, 27, 28, fig. 46,
bend the lower limbs on the body, at the hip. The muscle 28, fig. 46,
draws one leg over the other, (the position of a tailor when sewing.) The
muscles 27, 28, fig. 47, extend the lower limbs on the body, at the hip.
The muscles 29, 30, 31, fig. 46, extend the leg at the knee. The muscles
29, 30, fig. 47, bend the leg at the knee. The muscles 34, 36, fig. 46,
bend the foot at the ankle, and extend the toes. The muscles 31, 32, 33,
fig. 47, extend the foot at the ankle.]

_Note._ Let the anatomy and physiology of the muscular system be
reviewed, in form of topics, from figs 46, 47, or from the anatomical
outline plates No. 3 and 4.



CHAPTER X.

HYGIENE OF THE MUSCLES


173. _The muscles should be used, in order that the size and strength
of these organs may be adequate to the demand made upon them._ It is a
law of the system that the action and power of an organ are
commensurate, to a certain extent, with the demand made upon it; and
it is a law of the muscular system that, whenever a muscle is called
into frequent use, its fibres increase in thickness within certain
limits, and become capable of acting with greater force; while, on the
contrary, the muscle that is little used decreases in size and power.

_Illustrations._ 1st. The blacksmith uses and rests the muscles of his
arm when striking upon the anvil. They not only increase in size, but
become very firm and hard.

2d. The student uses the muscles of the arm but little, in holding his
books and pen; they not only become small, but soft.

3d. Let the student leave his books, and wield an iron sledge, and the
muscles of his arm will increase in size and firmness. On the other
hand, let the blacksmith assume the student's vocation, and the
muscles of his arm will become soft and less firm.

174. _When the muscles are called into action, the flow of blood in
the arteries and veins is increased._ The increased flow of blood in
the arteries and veins, causes a more rapid deposition of the
particles of matter of which the muscles are composed. If the
exercise is adequate to the power of the system, the deposit of new
material will exceed in quantity the particles of matter removed, and
both the size and energy of the muscles are increased. But there is a
limit to the muscles becoming strong by labor. Sooner or later, man
will attain his growth or power; yet by judicious exercise, care, and
discreet management, the greatest power of the muscles may be
preserved until advanced age.

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173-211. _Give the hygiene of the muscles._ 173. What is necessary
that muscles may attain size and strength? Give a law of the muscular
system. Show this by practical illustrations. 174. Why do muscles
increase in size when exercised?

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175. _The muscles are lessened in size and diminished in power when
the exercise is continued so as to produce a feeling of exhaustion._
The loss of material, in this instance, will exceed the deposition of
the atoms of matter. This is seen in the attenuated frames of
over-tasked domestic animals, as the horse. The same truth is
illustrated by the laborious agriculturist, who, in consequence of too
severe toil while gathering the products of the field, frequently
diminishes his weight several pounds in a few weeks. Exercise, either
for pleasure or profit, may fatigue, yet it should never be protracted
to languor or exhaustion, if the individual desires "a green old
age."

176. _The same amount of exercise will not conduce to the health of
all individuals._ If riding or walking one mile causes slight fatigue,
this may be beneficial; while, by travelling two miles, the exhaustion
may be highly injurious. Exercise and labor should be adapted to the
strength of particular individuals. How little soever the strength,
that must be the measure of exertion. Any other rule would be fatal to
the hopes of invigorating the system, either by exercise or labor.

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Is there a limit to the muscles becoming powerful by action? How may
the strength of muscles be kept until advanced age? 175. What is the
effect when exercise is continued until there is a feeling of
exhaustion? Give a practical illustration. What rule is mentioned in
regard to exercise? 176. Can all persons take the same amount of
exercise? What rule is given as to the amount of exercise?

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177. _Relaxation must follow contraction, or, in other words, rest
must follow exercise._ The necessity of relaxation, when a muscle has
been called into action, is seen in the example of a boy extending his
arm with a book in his hand, as a penalty. The boy can keep the arm
extended but a short time, make what effort he may. It is also seen in
the restlessness and feverish excitement that are evinced by persons
gazing on troops during days of review. The same is noted in shopping.
Such employments call into action the muscles that support the spinal
column in an erect position, and the languor or uneasiness is muscular
pain. The long-continued tension of a muscle enfeebles its action, and
eventually destroys its contractility.

178. _In school, the small children, after sitting a short time,
become restless._ If their position be changed, their imperfectly
developed muscles will acquire tone, and will again support the spinal
column erect without pain. The necessity for frequent recesses in
school, is founded on the organic law of muscular action alternating
with rest. The younger and feebler pupils are, the greater the
necessity for frequent recesses. We would not have the teacher think
that one half of the time should be spent in recesses; or the mother,
that her daughter is going to school to play. But we do maintain that
recesses should be given, and that they should be short and frequent,
especially for small and feeble scholars.

179. _Exhaustion is the inevitable result of continued muscular
contraction._ For example, let a lady ply the needle quickly for some
hours, and the muscles of the back and right arm will become
exhausted, which will be indicated by a sense of weariness in these
parts. A change of employment and position calls into action a
different set of muscles, and the exhausted organs are relieved.

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177. What is said of the contraction and relaxation of the muscles?
Give examples of the necessity of relaxing the muscles. 178. Why
should not small children be confined in one position for a long time?
What evils result from this practice? What class of pupils should have
recesses most frequently? 179. What effect has continued muscular
contraction?

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180. _Much more labor will be accomplished by taking time to relax the
exhausted muscles_, or by so changing the employment as to bring into
action a new set of muscles; the woodman thus relieves himself, by
sawing and splitting alternately. This principle applies to the labor
of the horse and ox; and it is also applicable to all kinds of
employment. With the invalid convalescing from fever, relapses result
from inattention to these laws. When a patient is recovering from
sickness, his physician should take care that his exercise be proper,
neither too much, too little, nor too long continued.

181. _The muscles of growing youths will not endure so much exercise
or labor as those of mature men._ In youth a portion of the vital, or
nervous energy of the system, is expended upon the growth of the
organs of the body, while in the individual who has attained his
growth, this expenditure is not demanded; consequently severe labor or
exercise should not be imposed on growing children.

_Observation._ In the campaigns of Napoleon Bonaparte, his army was
frequently recruited by mere boys. He complained to the French
government, because he was not supplied with men of mature years, as
the youths could not endure the exertion of his forced marches.

182. _The muscles should be gradually called into action._ These
organs in action require more blood and nervous fluid than when at
rest. As the circulation of these fluids can only be increased in a
gradual manner, it follows, that, when the muscular system has been in
a state of rest, it should not suddenly be called into vigorous
action. On arising from a bed, lounge, or chair, the first movements
of the limbs should be slow, and then gradually increased.

_Observation._ if a man has a certain amount of work to perform in
nine hours, and his muscles have been in a state of rest, he will do
it with less fatigue by performing half the amount of the labor in
five hours, and the remainder in four hours. The same principle should
be regarded in driving horses and other beasts of burden.

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180. How can the greatest amount of labor be secured with the least
exhaustion to the muscles? 181. Why should not severe labor be imposed
on growing children? 182. How should the muscles be called into
action?

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183. _The muscles should be rested gradually, when they have been
vigorously used._ If a person has been making great muscular exertion
in cutting wood, or any other employment, instead of sitting down to
rest, he should continue muscular action, for a short time, by some
moderate labor or amusement.

184. _If the system has been heated by muscular action, and the skin
is covered with perspiration, avoid sitting down_ "to cool" in a
current of air; rather, put on more clothing, and continue to exercise
moderately. In instances when severe action of the muscles has been
endured, bathing and rubbing the skin of the limbs and joints that
have been used, are of much importance. The laboring agriculturist and
industrious mechanic, by reducing to practice this suggestion, would
thus prevent soreness of the muscles, and stiffness of the joints.

185. _The muscles should be abundantly supplied with pure blood._ This
state of the circulating fluid requires a healthy condition of the
digestive apparatus, and that the skin should be kept warm by proper
clothing, clean by bathing, and be acted upon by pure air and good
light; the movements of the ribs and diaphragm should be unrestricted,
and the lungs should have ample volume and be supplied with pure air.
In all instances, muscular power is greatest when the preceding
conditions exist, as the muscles are then stimulated by pure blood;
consequently, it is of practical importance to the mechanic, the
farmer, the man of leisure, and not less so to the ladies, to observe
these conditions, whatever vocation of life they pursue.

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183. How should the muscles be rested when they have been vigorously
used? 184. What precaution is given when the skin is covered with
perspiration? How may soreness of the muscles, consequent upon severe
action, be prevented? 185. Should the muscles be supplied with pure
blood? When is muscular power the greatest?

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186. _The muscles should be used in pure air._ The purer the air we
breathe, the more stimulating the blood supplied to the muscles, and
the longer they can be used in labor, walking, or sitting, without
fatigue and injury; hence the benefit derived in thoroughly
ventilating all inhabited rooms. For the same reason, if the air of
the sick-room is pure, the patient will sit up longer than when the
air is impure.

_Observation._ It is a common remark that sick persons will sit up
longer when riding in a carriage, than in an easy chair in the room
where they have lain sick. In the one instance, they breathe pure air;
in the other, usually, a confined, impure air.

187. _The muscles should be exercised in the light._ Light,
particularly that of the sun, exercises more or less influence on man
and the inferior animals as well as on plants. Both require the
stimulus of this agent. Shops occupied by mechanics, kitchens, and
sitting-rooms, should be well lighted, and situated on the sunny side
of the house. Cellar kitchens and underground shops should be avoided.
For similar reasons, students should take their exercise during the
day, rather than in the evening, and, as much as possible, laborers
should avoid night toil.

_Illustrations._ Plants that grow in the shade, as under trees, or in
a dark cellar, are of lighter color and feebler than those that are
exposed to the light of the sun. Persons that dwell in dark rooms are
paler and less vigorous than those who inhabit apartments well
lighted, and exposed to the rays of the sun.

  -=-=-=-=-=-=-=-=-=-=-=-=

186. Why should the muscles be used in pure air? Give a common
observation. 187. What effect has light on the muscular system? What
should the laborer avoid? Why should not students take their daily
exercise in the evening? How is the influence of solar light
illustrated?

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188. _Exercise should be regular and frequent._ The system needs this
means of invigoration as regularly as it does new supplies of food. It
is no more correct that we devote several days to a _proper_ action of
the muscles, and then spend one day inactively, than it is to take a
_proper_ amount of food for several days, and then withdraw this
supply for a day. The industrious mechanic and the studious minister
suffer as surely from undue confinement as the improvident and
indolent. The evil consequences of neglect of exercise are gradual,
and steal slowly upon an individual. But sooner or later they are
manifested in muscular weakness, dyspepsia, and nervous irritability.

_Observation._ The custom among farmers of enduring severe and undue
toil for several successive days, and then spending one or two days in
idleness to _rest_, is injudicious. It would be far better to do less
in a day, and continue the labor through the period devoted to
idleness, and then no rest will be demanded.

189. _Every part of the muscular system should have its appropriate
share of exercise._ Some employments call into exercise the muscles of
the upper limbs, as shoe-making; others, the muscles of the lower
limbs; while some, the muscles of both upper and lower limbs, with
those of the trunk, as farming. In some kinds of exercise, the lower
limbs are mainly used, as in walking; in others, the upper limbs; and
again, the muscles of the trunk, together with those of the upper and
lower limbs, as in archery, quoits, playing ball. Those trades and
kinds of exercise are most salutary, in which all the muscles have
their due proportion of action, as this tends to develop and
strengthen them equally. Thus labor upon the farm and domestic
employment are superior as vocations, and archery, quoits, and
dancing, if the air is pure, among the pastimes. For sedentary
persons, that kind of exercise is best which calls into action the
greatest number of muscles.

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188. How should exercise be taken? What is said respecting irregular
exercise? Are the consequences of neglected exercise immediately
apparent? What practical observation is given? 189. Should every
muscle have its due amount of exercise? Mention some employments that
only call into action the muscles of the upper limbs. Those of the
lower limbs, those of the trunk and limbs. Mention, in the different
pastimes, what muscles are called into action.

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190. _The proper time for labor or exercise should be observed._ This
is modified by many circumstances. As a general rule, the morning,
when the air is pure and the ground dry, is better than the evening;
for then, the powers of the body are greatest. Severe exercise and
labor should be avoided immediately before or after eating a full
meal, for the energies of the system are then required to perform the
digestive function. For similar reasons, it is not an appropriate time
for energetic muscular action immediately before or after severe
mental toil, as the powers of the system are then concentrated upon
the brain.[6]

   [6] It appears to be a fact, that no two important organs can be
       called into intense action at the same time, without injury to
       both, as well as to the general system. This arises from the
       circumstance that an organ, when in functional action, attracts
       fluids (sanguineous and nervous) from other organs of the
       system. Except in a few instances of high health in youth, the
       power of the system is not adequate to supply more than one
       organ in action with the appropriate fluids at the same time.

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What kinds of exercise are best? 190. What rule is given respecting
the time for exercise? 191. Why do the muscles require sleep? What is
the effect of an inversion of the law of rest?

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191. _The muscles require sleep to restore their expended energies._
Among the arrangements of creative wisdom, no one harmonizes with the
wants of the system more than the alternation of day and night. The
natural inclination of man to sleep, is in the stilly hour of night,
when all nature reposes, and to be in action during the light of day.
An inversion of this law of rest causes greater exhaustion of the
system than the same amount of exertion during daylight. This is
illustrated by the wearied and exhausted condition of watchers,
night-police, and other individuals who spend a part of the night in
some active business of life.

192. _The muscles should not be compressed._ Compression prevents the
blood from passing to the muscles with freedom; consequently, they are
not supplied with material to renovate and promote their growth.
Again, pressure stimulates the lymphatics to action; and by the
increased activity of these vessels the muscles are attenuated. In the
case of a man with a fractured limb, the muscles are not only
enfeebled by inaction, but diminished in size by compression from the
dressing. Limbs enfeebled in this way will not recover their size,
tone, and strength, until the bandages are removed, and a proper
amount of exercise taken.

193. The pressure of tight dresses, under the name of a "snug fit,"
enfeebles the muscles of the back, and is a common cause of projecting
shoulders and curvature of the spinal column. Thus every appendage to
the dress of ladies which prevents free motion of the muscles of the
chest and spinal column, weakens the muscles thus restrained, and not
only prevents the proper expansion of the lungs, but, by weakening the
muscles which sustain the spine, induces curvature and disease.
Whalebone, wood, steel, and every other unyielding substance, should
be banished from the toilet, as enemies of the human race.

194. _The mind exerts a great influence upon the tone and contractile
energy of the muscular system._ A person acting under a healthy mental
stimulus will make exertion with less fatigue than he would without
this incentive. For this reason, a sportsman will pursue his game
miles without fatigue, while his attendant, not having any mental
stimulus, will become weary. Again, if the sportsman spends some hours
in pursuit of his favorite game without success, a feeling of languor
creeps over him; but while he is thus fatigued and dispirited, let him
catch a glimpse of the game,--his wearied feelings are immediately
dissipated, and he presses on with renewed energy and recruited
strength.

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192. Why should not the muscles be compressed? 193. What is the effect
of tight clothing upon the muscles? 194. What is said of the influence
of the mind upon muscular activity? Give an illustration of mental
stimulus coöperating with muscular activity in the case of a
sportsman.

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195. This principle was well illustrated in the retreat from Russia of
the defeated and dispirited French army. When no enemy was near,
they had hardly strength sufficient to carry their arms; but no
sooner did they hear the report of the Russian guns, than new life
seemed to pervade them, and they wielded their weapons powerfully
until the foe was repulsed, then there was a relapse to weakness, and
prostration followed. It is thus with the invalid when riding for
his health;--relate an anecdote, or excite this mental stimulus by
agreeable conversation, and much benefit will accrue from the ride
to the debilitated person. So it is in the daily vocations of
life; if the mind have some incentive, the tiresomeness of labor
will be greatly diminished. Let an air of cheerfulness ever pervade
our every employment, and, like music, "it sweetens toil."

196. Facts illustrative of the inutility of calling the muscles into
action, without the coöperation of the mind, are seen in the
spiritless aspect of many of our boarding school processions, when a
walk is taken merely for exercise, without having in view any
attainable object. But present to the mind a botanical or geological
excursion, and the saunter will be exchanged for the elastic step, the
inanimate appearance for the bright eye and glowing cheek. The
difference is, simply, that, in the former case, the muscles are
obliged to work without that full nervous impulse so essential to
their energetic action; and that, in the latter, the nervous influence
is in full and harmonious operation.

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195. Give an illustration of mental stimulus coöperating with muscular
activity in the case of the dispirited French army in their retreat
from Russia. How can a union of mental impulse and muscular action be
beneficial to an invalid? Does this same principle apply to those who
labor? 196. Give an instance of the different effects produced by the
absence and presence of the mental stimulus.

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197. It must not, however, be supposed that a walk simply for the sake
of exercise can never be beneficial. Every one, unless prevented by
disease, should consider it a duty to take exercise every day in the
open air; if possible, let it be had in combination with harmonious
mental exhilaration; if not, let a walk, in an erect position, be made
so brisk as to produce rapid respiration and circulation of the blood,
and in a dress that shall not interfere with free motions of the arms
and free expansion of the chest.

_Observation._ The advantages of combining harmonious mental
excitement, with muscular activity, is thus given by Dr. Armstrong:--

                               "_In whate'er you sweat,
         Indulge your taste._ Some love the manly toils
         The tennis some, and some the graceful dance;
         Others, more hardy, range the purple heath
         Or naked stubble, where, from field to field,
         The sounding covies urge their lab'ring flight,
         Eager amid the rising cloud to pour
         The gun's unerring thunder; and there are
         Whom still the mead of the green archer charm.
         _He chooses best whose labor entertains
         His vacant fancy most; the toil you hate
         Fatigues you soon, and scarce improves your limbs._"

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197. May not a walk, simply as an exercise, be beneficial? What is
preferred?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XI.

HYGIENE OF THE MUSCLES, CONTINUED.


198. _The erect attitude lessens the exhaustion of the muscles._ A
person whose position is erect will stand longer, walk further, and
perform more labor, than an individual whose position is stooping, but
equal in all other respects. The manly port in an erect attitude,
depends chiefly upon the action of the muscles of the back; and it
follows that the fewer the muscles in a state of tension, the less the
draught upon the nervous system, and the less its exhaustion. Another
advantage which attends the erect position is, the trunk and head are
balanced upon the bones and cartilages of the spinal column. If the
body slightly incline forward, the muscles attached to the posterior
side of the spine, by a gentle contraction, will bring it to the
perpendicular, and even incline it backward. This is immediately
removed by a slight contraction of the muscles upon the anterior side
of the spinal column.

199. In the erect position, there is a constant slight oscillation
of the body backward and forward, like the movement of a pendulum;
while, in the stooping posture, the muscles on the posterior side
of the spinal column are kept in a state of continued tension and
contraction, to prevent the body from falling forward. This enfeebles
the muscles of the back, and exhausts the nervous energy, while the
erect position favors their development and power, because there is
an alternate contraction and relaxation of the muscles. Again, in the
stooping position, the lower limbs are curved at the knee. In this
attitude, there is a constant tension of the muscles of the lower
extremities, which produces muscular exhaustion.

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198. Why will a person who stands erect walk further, and perform more
labor, than if he assumed the stooping posture? 199. Why are the
muscles of the back so soon exhausted in the stooping position?

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[Illustration: Fig. 48. 1, A perpendicular line from the centre of the
feet to the upper extremity of the spinal column, where the head rests.
2, 2, 2, The spinal column, with its three natural curves. Here the head
and body are balanced upon the spinal column and joints of the lower
extremities, so that the muscles are not kept in a state of tension. This
erect position of the body and head is always accompanied with straight
lower limbs.]

[Illustration: Fig. 49. 1, A perpendicular line from the centre of the
feet. 2, Represents the unnatural curved spinal column, and its relative
position to the perpendicular, 1. The lower limbs are curved at the knee,
and the body is stooping forward. While standing in this position, the
muscles of the lower limbs and back are in continued tension, which
exhausts and weakens them.]

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What is represented by figs. 48 and 49?

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200. When it is necessary to call into action a part of the muscles of
the system in the performance of any duty, as those of the lower limbs
in walking, if the muscles of other parts are in a state of inaction,
the influence of the nervous system can be determined in an undivided
manner upon those parts of the lower limbs in action; hence they will
not so soon become wearied or exhausted, as when this influence is
divided between a greater number of muscles. In performing any labor,
as in speaking, reading, singing, mowing, sewing, &c., there will be
less exhaustion, and the effort can be longer maintained in the erect
position of the body and head, than in a stooping attitude.

_Experiment._ Hold in each hand a pail of water or equal weights, in a
stooping posture, as long as it can be done without much suffering and
injury. Again, when the muscular pain has ceased, hold the same pails
of water, for the same length of time, in an erect posture, and note
the difference in the fatigue of the muscles.

201. If the stooping posture is acquired in youth, we are quite
certain of seeing the deformed shoulders in old age. Hence the
importance of duly exercising the muscles of the back, for when they
are properly developed, the child can and will stand erect. In this
attitude, the shoulders will be thrown back, and the chest will become
broad and full.

202. Pupils, while standing during recitations, often inadvertently
assume the attitude represented by fig. 49, and it is the duty of
teachers to correct this position when assumed. When a child or adult
has contracted a habit of stooping, and has become round-shouldered,
it can be measurably, and generally, wholly, remedied by moderate and
repeated efforts to bring the shoulders back, and the spinal column in
an erect position. This deformity can and should be remedied in our
schools. It may take months to accomplish the desired end, yet it can
be done as well under the direction of the kind instructor, as under
the stern, military drill sergeant, who never fails to correct this
deformity among his raw recruits.

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200. What suggestion when it is necessary to call into action a part
of the muscular system? Give the experiment that illustrates this
principle. 201. Why should a child he taught to stand erect? 202. How
can round shoulders acquired by habit be remedied?

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[Illustration: Fig. 50. A proper position in sitting.]

203. _The child should be taught to sit erect when employed in study
or work._ This attitude favors a healthy action of the various organs
of the system, and conduces to beauty and symmetry of form. Scholars
are more or less inclined to lean forward and place the elbow on the
table or desk, for support and this is often done when their seats
are provided with backs. Where there is a predisposition to curvature
of the spine, no position is more unfavorable or more productive of
deformities than this; for it is usually continued in one direction,
and the apparent deformity it induces is a projection of the
shoulders. If the girl is so feeble that she cannot sit erect, as
represented by fig. 50, let her stand or recline on a couch; either is
preferable to the position represented by fig. 51. In furnishing
school-rooms, care should be taken that the desks are not so low as to
compel the pupils to lean forward in examining their books.

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203. Why should the erect attitude be assumed in sitting?

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[Illustration: Fig. 51. An improper position in sitting.]

204. _The muscles, when exhausted, cannot endure continued effort._
When the energies of the muscular system have been expended by severe
and long-continued exercise, or the brain and nervous system
prostrated by protracted mental effort, the muscles are unfitted to
maintain the body erect in standing or sitting for a long time, as the
nervous system, in its exhausted state, cannot supply a sufficient
amount of its peculiar influence to maintain the supporting muscles of
the body and head in a state of contraction. Hence, a child or adult,
when much fatigued, should not be compelled to stand or sit erect in
one posture, but should be permitted to vary the position frequently,
as this rests and recruits both the muscular and the nervous system.

205. _A slight relaxation of the muscles tends to prevent their
exhaustion._ In walking, dancing, and most of the mechanical
employments, there will be less fatigue, and the movements will be
more graceful, when the muscles are slightly relaxed. When riding in
cars or coaches, the system does not suffer so severely from the jar
if there is a slight relaxation of the muscles, as when they are in a
state of rigid contraction.

_Experiments._ Attempt to bow with the muscles of the limbs and trunk
rigid, and there will be a stiff bending of the body only at the
hip-joint. On the other hand, attempt to bow with the muscles
moderately relaxed; the ankle, the knee, and the hip-joint will
slightly bend, accompanied with an easy and graceful curve of the
body.

206. The muscles when relaxed, together with the yielding character of
the cartilage, and the porous structure of the ends of the bones that
form a joint, diffuse or deaden the force of jars, or shocks, in
stepping suddenly down stairs, or in falling from moderate heights.
Hence, in jumping or falling from a carriage, or any height, the shock
to the organs of the system may be obviated in the three following
ways: 1st. Let the muscles be relaxed, not rigid. 2d. Let the limbs be
bent at the ankle, knee, and hips; the head should be thrown slightly
forward, with the trunk a little stooping. 3d. Fall upon the toes, not
the heel.

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204. When are the muscles unfitted to maintain the system erect either
in standing or sitting? What is necessary when this condition of the
system exists? 205. Why should the muscular system be slightly relaxed
in walking, &c.? Give illustrative experiments. 206. What is the
reason that we do not feel the jar in falling from a moderate height?

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_Experiments._ Stand with the trunk and lower limbs firm, and the
muscles rigid; then jump a few inches perpendicularly to the floor,
and fall upon the heels. Again, slightly bend the limbs, jump a few
inches, and fall upon the toes, and the difference in the force of the
shock, to the brain and other organs, will be readily noticed.

207. _The muscles require to be educated, or trained._ The power of
giving different intonations in reading, speaking, singing, the varied
and rapid executions in penmanship, and all mechanical or agricultural
employments, depend, in a measure, upon the education of the muscles.
In the first effort of muscular education, the contractions of the
muscular fibres are irregular and feeble, as may be seen when the
child begins to walk, or in the first efforts of penmanship.

208. _Repetition of muscular action is necessary._ To render the
action of the muscles complete and effective, they must be called into
action repeatedly and at proper intervals. This education must be
continued until not only each muscle, but every fibre of the muscle,
is fully under the control of the will. In this way persons become
skilful in every employment. In training the muscles for effective
action, it is very important that correct movements be adopted at the
commencement. If this is neglected, the motions will be constrained
and improper, while power and skill will be lost.

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How is this shown by experiment? 207. Upon what do the different
intonations of sound or mechanical employments depend? Why are the
first efforts in educating the muscles indifferent or irregular? 208.
Why is repetition of muscular action necessary? Why is it important
that correct movements be adopted in the first efforts of muscular
education?

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_Illustration._ If a boy, while learning to mow, is allowed to swing
his scythe in a stooping position, twisting his body at every sweep of
the scythe, he will never become an easy, efficient mower. Proper
instruction is as necessary in many of the agricultural branches as in
the varied mechanical employments.

[Illustration: Fig. 52. An improper, but not an unusual position, when
writing.]

[Illustration: Fig. 53. A proper position, when writing.]

209. _Good penmanship requires properly trained muscles._ To a
deficient analysis of the movements of the arm, hand, and fingers, on
the part of teachers and pupils in penmanship, together with an
improper position in sitting, is to be ascribed the great want of
success in acquiring this art. The pen should be held loosely, and
when the proper position is attained, the scholar should make an
effort to imitate some definite copy as nearly as possible. The
movements of the fingers, hand, and arm, necessary to accomplish this,
should be made with ease and rapidity, striving, at each effort, to
imitate the copy more nearly.

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How is this illustrated? 209. Why have so many pupils failed in
acquiring good penmanship?

  -=-=-=-=-=-=-=-=-=-=-=-=

210. When the arm, hand, and fingers are rigid, the large muscles,
that bend and extend these parts, are called into too intense action.
This requires of the small muscles, that produce the lateral
movements, which are essential to rapidity in writing, an effort which
they cannot make, or can with difficulty accomplish.

_Experiment._ Vigorously extend the fingers by a violent and rigid
contraction of the muscles upon the lower part of the arm, and the
lateral movement which is seen in their separation cannot be made. But
gently extend the fingers, and their oblique movements are made with
freedom.

211. An individual who is acquainted with the laws of health, whose
muscles are well trained, will perform a certain amount of labor with
less fatigue and waste to the system, than one who is ignorant of the
principles of hygiene, and whose muscles are imperfectly trained.
Hence the laboring poor have a deep interest in acquiring a knowledge
of practical physiology, as well as skill in their trade or vocation.
It is emphatically true to those who earn their bread by the "sweat of
their brow," that "knowledge is power."

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210. What is said of the lateral and oblique movements of the arm,
hand, and fingers in writing? How is this shown by experiment? 211.
Why is the study of physiology and hygiene of utility to the laborer?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XII.

THE TEETH.


212. The teeth, in composition, nutrition, and growth, are different
from other bones of the body. They vary in number at different periods
of life, and, unlike other bones, they are exposed to the immediate
action of atmospheric air and foreign substances. The bones of the
system, generally, when fractured, unite; but there is never a
permanent union of a tooth when broken.


ANATOMY OF THE TEETH.

213. The TEETH are attached to the upper and lower jaw-bone, by means
of bony sockets, called _al´ve-o-lar_ processes. These give great
solidity to the attachment of the teeth, and frequently render their
extraction difficult. The gums, by their fibrous, fleshy structure,
serve to fix the teeth more firmly in the jaw.

_Observation._ When a _permanent_ tooth is extracted, these bony
processes are gradually absorbed, so that in advanced age there
remains only the jaw-bone covered by the lining membrane of the gum.
This accounts for the narrow jaw and falling in of the lips in old
age. Frequently, a piece of the alveolar process comes out with the
tooth when extracted, and the dentist has then the credit of "breaking
the jaw." No great injury results from the removal of the process in
this manner.

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212. What is said of the teeth? In what respect do they differ from
other bones of the body? 213-218. _Give the anatomy of the teeth._
213. What confines the teeth in the jaw-bone? What becomes of the
socket when a tooth is removed? What effect has this absorption upon
the jaw and lips?

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214. The teeth are formed in the interior of the jaws, and within
_dent´al cap´sules_, (membranous pouches,) which are enclosed within
the substance of the bone, and present in their interior a fleshy bud,
or granule, from the surface of which exudes the ivory, or the bony
part of the tooth. In proportion as the tooth is formed, it rises in
the socket, which is developed simultaneously with the tooth, and
passes through the gum, and shows itself without.

[Illustration: Fig. 54. 1, The body of the lower jaw. 2, Ramus, or branch
of the jaw, to which the muscles that move it are attached. 3, 3, The
processes which unite the lower jaw with the head. _i_, The middle and
lateral incisor tooth of one side. _b_, The bicuspid teeth. _c_, The
cuspids, or eye teeth. m, The three molar teeth. A, shows the relation of
the permanent to the temporary teeth.]

215. The first set, which appears in infancy, is called _tem´po-ra-ry_,
or milk teeth. They are twenty in number; ten in each jaw. Between
six and fourteen years of age, the temporary teeth are removed, and the
second set appears, called _per´ma-nent_ teeth. They number
thirty-two, sixteen in each jaw.

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214. Where and how are the teeth formed? Explain fig. 54. 215. What
are the first set called? How many in each jaw? The second set? How
many in number?

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216. The four front teeth in each jaw are called _in-ci´sors_,
(cutting teeth;) the next tooth in each side, the _cus´pid_, (eye
tooth;) the next two, _bi-cus´pids_, (small grinders;) the next two,
_mo´lars_, (grinders.) The last one on each side of the jaw is called
a _wisdom tooth_, because it does not appear until a person is about
twenty years old. The incisors, cuspids, and bicuspids, have each but
one root. The molars of the upper jaw have three roots, while those of
the lower jaw have but two.

[Illustration: Fig. 55. The permanent teeth of the upper and lower jaw.
_a_, _b_, The incisors. _c_, The cuspids. _d_, _e_, The bicuspids. _f_,
_g_, The molars, (double teeth.) _h_, The wisdom teeth.]

_Observation._ The shape of the teeth in different species of animals
is adapted to the kind of food on which they subsist. Those animals
that feed exclusively on flesh, as the lion, have the cuspids, or
canine teeth, largely developed, and the molars have sharp cutting
points. Those animals that feed on grass and grain, as the horse and
the sheep, have their molar teeth more rounded and flat on the crown.
The human teeth are adapted to feed on fruits, grain, or flesh, as
they are less pointed than those of the cat, and more pointed than
those of the sheep.

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216. Give the names of the permanent teeth. What teeth have but one
root, or "fang"? How many roots have the molars of the upper jaw? Of
the lower jaw? What is said of the shape of the teeth in different
species of animals?

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217. The teeth are composed principally of two substances--the
_i´vo-ry_ and the _en-am´el_. The internal part of the tooth or the
ivory, is harder and more enduring than bone, and forms the body of
the tooth. The enamel is remarkable for its hardness, and varies
somewhat in color with the age, temperament, habits, and manner of
living of different individuals. When any part of the enamel is
destroyed, it is never regenerated.

[Illustration: Fig. 56. A side view of the body and enamel of a front
tooth.]

[Illustration: Fig. 57. A side view of a molar tooth. 1, The enamel. 2,
The body of the tooth. 3, The cavity in the crown of the tooth that
contains the pulp. 4, A nerve that spreads in the pulp of the tooth. 5,
An artery that ramifies in the pulp of the tooth.]

218. Each tooth is divided into two parts, namely, _crown_ and _root_.
The crown is that part which protrudes from the jaw-bone and gum, and
is covered by the highly polished enamel. The root, or "fang," is
placed in the sockets of the jaw, and consists of bony matter. Through
this bony substance several small vessels pass, to aid in the growth
and also in the removal of the tooth. There are, beside these
vessels, small white cords passing to each tooth, called _nerves_.
(See fig. 57.) When these nerves are diseased, we have the toothache.

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217. Give the structure of the teeth. What is said of the enamel? 218.
Into how many parts are the teeth divided? Describe the crown. The
root. What vessels pass through the bony matter? What is their use?

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PHYSIOLOGY OF THE TEETH.

219. The use of the teeth is twofold. 1st. By the action of the
incisors the food is divided, while the molars grind or break down the
more solid portions of it. By these processes, the food is prepared to
pass more easily and rapidly into the stomach.

220. In the mastication of food there are two movements of the lower
jaw--the action by which the teeth are brought together, and the
lateral motion. In the former, the food is cut or divided, the jaws
acting like shears. This movement is produced by the action of two
large muscles situated on each side of the head and face.

_Observation._ The muscles attached to the lower jaw are of great
strength; by their action alone, some persons are enabled to bite the
hardest substances. By putting the fingers upon the side of the head
above and in front of the ears, and upon the face above the angle of
the jaw, while masticating food, the alternate swelling and relaxation
of these muscles will be clearly felt.

221. The lateral, or grinding movement of the teeth, is produced by
the action of a strong muscle that is attached to the lower jaw on the
inside.

_Observation._ Those animals that live solely on flesh, have only the
cutting, or shear-like movement of the jaws. Those that use
vegetables for food, have the grinding motion; while man has both the
cutting and grinding movement.

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219-222. _Give the physiology of the teeth._ 219. Give one of the
functions of the teeth. 220. How many movements of the lower jaw in
masticating food? What effect has the first movement upon the food?
How produced? What is the character of the masticating muscles? 221.
How is the grinding motion of the teeth produced? What is said of the
movements of the teeth in different animals?

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222. 2d. The teeth aid us in articulating with distinctness certain
letters and words. An individual who has lost his front teeth cannot
enunciate distinctly certain letters called dental. Again, as the
alveolar processes are removed by absorption soon after the removal of
the teeth, the lips and cheeks do not retain their former full
position, thus marring, in no slight degree, the symmetry of the lower
part of the face. Consequently, those simple observances that tend to
the preservation of the teeth are of great practical interest to all
persons.


HYGIENE OF THE TEETH.

223. _To preserve the teeth, they must be kept clean._ After eating
food, they should be cleansed with a brush and water, or rubbed with a
piece of soft flannel, to prevent the _tartar_ collecting, and to
remove the pieces of food that may have lodged between them.
Toothpicks may be useful in removing any particles inaccessible to the
brush. They may be made of bone, ivory, or the common goose-quill.
Metallic toothpicks should not be used, as they injure the enamel.

224. _The mouth should be cleansed with pure tepid water at night, as
well as in the morning_; after which the teeth should be brushed
upward and downward, both on the posterior and anterior surfaces. It
may be beneficial to use refined soap, once or twice every week, to
remove any corroding substance that may exist around the teeth; care
being taken to thoroughly rinse the mouth after its use.

225. _Food or drink should not be taken into the mouth when very hot
or very cold._ Sudden changes of temperature will crack the enamel,
and finally produce decayed teeth.

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222. What is another use of the teeth? 223-232. _Give the hygiene of
the teeth._ 223. How can the teeth be preserved? By what means? 224.
How often should they be cleansed? 225. What is said of very hot or
cold drinks?

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_Observation._ On this account, smoking is pernicious, because the
teeth are subjected to an alternate inhalation of both cold and warm
air.

226. _The temporary teeth should be removed as soon as they become
loose._ If a permanent tooth makes it appearance before the first is
removed, or has become loose, the milk tooth, although not loose,
should be removed without delay. This is necessary that the second set
of teeth may present a regular and beautiful appearance.

227. _In general, when the permanent teeth are irregular, one or more
should be removed._ If the teeth are crowded and irregular, in
consequence of the jaw being narrow and short, or when they press so
hard upon each other as to injure the enamel, remove one or more to
prevent their looking unsightly, and in a few months the remaining
teeth, with a little care, will fill the spaces.

_Observation._ When it is necessary to remove a tooth, apply to some
skilful operator. It requires as much skill and knowledge to extract
teeth _well_, as it does to amputate a limb; yet some persons, who
possess strong arms, will obtain a pair of forceps, or a tooth-key,
and hang out the sign of "surgeon-dentist," although ignorant of the
principles that should guide them.

228. _It is not always necessary to have teeth extracted when they
ache._ The nerve, or the investing membrane of the root, may be
diseased, and the tooth still be sound. In such instances, the tooth
should not be extracted, but the diseased condition may be remedied by
proper medication. There are many sound teeth, that become painful, as
already mentioned, which are unnecessarily removed.

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Why is smoking injurious to the teeth? 226. What remark respecting the
temporary teeth? 227. What remarks respecting the permanent teeth? Do
those persons that extract teeth require skill as well as knowledge?
228. Why should not teeth be extracted at all times when they are
painful?

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_Illustration._ Dr. H. M., of Belfast, Me., related to me that an
individual in that vicinity had his teeth, (all of them sound,) on one
side of the lower jaw, extracted by an ignoramus of a "tooth-puller,"
and this without any relief from pain. The disease was tic douloureux,
which was relieved by Dr. M.

229. _The preservation of the teeth requires that they be frequently
examined._ When a part of the enamel is removed, and a small portion
of the body of the tooth has become carious, in many instances such
teeth may be preserved from further decay by having them filled or
"plugged" with _gold foil_. All amalgams, pastes, and cheap patent
articles for filling, should be avoided, if you would preserve both
the teeth and the general health.

230. The practice of cracking nuts with the teeth, or of lifting heavy
bodies, and the constant habit of biting thread, should be avoided, as
they finally destroy the enamel.

231. _All acidulated drinks and mineral waters, that "set the teeth on
edge," are injurious._ All tooth-powders and washes that contain any
article that is acid, corrosive, or grinding, should be banished from
the toilet. Tobacco is not a preservative of the teeth. It contains
"grit," which wears away the enamel; beside, when chewed, it
debilitates the vessels of the gums, turns the teeth yellow, and
renders the breath and the appearance of the mouth disagreeable.

232. Healthy persons have generally sound teeth, while feeble persons
have decayed teeth. For this reason, we should try to learn and
practise the few simple rules that promote health.

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Give an illustration of the removal of sound teeth. 229. How may
decaying teeth be preserved? What should be avoided in the filling of
teeth? 230. What practices should also be avoided? 231. What is said
of acidulated drinks? What effect has the chewing of tobacco upon the
teeth? 232. What is one reason for preserving health?

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CHAPTER XIII.

THE DIGESTIVE ORGANS.


233. From the earliest existence of the human system to the last ray
of life, change is impressed upon it by the Giver of this curious
fabric. New atoms of matter are deposited, while the old and now
useless particles are constantly removed. The material necessary to
sustain the growth of the body in early life, and also to repair the
waste that is unceasing to animal existence, is the food we eat.

234. Food, animal or vegetable, contains most of the elements of the
different tissues of the system, yet it must undergo certain essential
alterations before it can become a part of the body. The first change
is effected by the action of the _Digestive Organs_.


ANATOMY OF THE DIGESTIVE ORGANS

235. The DIGESTIVE ORGANS are the _Mouth_, _Teeth_,[7] _Sal´i-va-ry
Glands_, _Phar´ynx_, _OE-soph´a-gus_, (gullet,) _Stom´ach_,
_In-tes´tines_, (bowels,) _Lac´te-als_, (milk, or chyle vessels,)
_Tho-rac´ic Duct_, _Liv´er_, and the _Pan´cre-as_, (sweetbread.)

   [7] See Chapter XII.

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233. What is impressed upon the human system from its earliest
existence? What maintains this change? 234. Has animal or vegetable
food any resemblance to the different tissues of which it finally
forms a part? By what organs is the first change in the food effected?
235-258. _Give the anatomy of the digestive organs._ 235. Name them.
236. Describe the mouth.

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MOUTH is an irregular cavity, which contains the instruments of
mastication and the organs of taste. It is bounded in front by the
lips; on each side by the internal surface of the cheeks; above, by
the _hard palate_ (roof of the mouth) and teeth of the upper jaw;
below, by the tongue and teeth of the lower jaw; behind, it is
continuous with the pharynx, but is separated from it by a kind of
movable curtain, called the _soft palate_. This may be elevated or
depressed, so as to close the passage or leave it free.

237. The SALIVARY GLANDS are six in number; three on each side of the
jaw. They are called the _pa-rot´id_, the _sub-max´il-la-ry_ and the
_sub-lin´gual_.

[Illustration: Fig. 58. A view of the salivary glands in their proper
situations. 1, The parotid gland. 2, Its duct. 3, The submaxillary gland.
4, Its duct. 5, The sublingual gland, brought to view by the removal of a
section of the lower jaw.]

238. The PAROTID GLAND, the largest, is situated in front of the
external ear, and behind the angle of the jaw. A duct (Steno's) from
this gland opens into the mouth, opposite the second molar tooth of
the upper jaw.

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237. How many glands about the mouth? Give their names. What does fig.
58 represent? 238. Describe the parotid gland.

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239. The SUBMAXILLARY GLAND is situated within the lower jaw, anterior
to its angle. Its excretory duct (Wharton's) opens into the mouth by
the side of the _fræ´num lin´guæ_, (bridle of the tongue.)

240. The _SUBLINGUAL GLAND_ is elongated and flattened, and situated
beneath the mucous membrane of the floor of the mouth, on each side of
the frænum linguæ. It has seven or eight small ducts, which open into
the mouth by the side of the bridle of the tongue.

_Observation._ In the "mumps," the parotid gland is diseased. The
swelling under the tongue called the "frog" is a disease of the
sublingual gland.

[Illustration: Fig. 59. A side view of the face, oesophagus, and trachea.
1, The trachea (wind pipe.) 2, The larynx. 3, The oesophagus. 4, 4, 4,
The muscles of the upper portion of the oesophagus forming the pharynx.
5, The muscle of the cheek. 6, The muscle that surrounds, the mouth. 7,
The muscle that forms the floor of the mouth.]

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239. The submaxillary. 240. The sublingual. What observation
respecting these glands? What does fig. 59 represent?

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241. The PHARYNX is a membranous sac, situated upon the upper portion
of the spinal column. It extends from the base of the skull to the top
of the _tra´che-a_, (windpipe,) and is continuous with the oesophagus.
From the pharynx are four passages; one opens upward and forward to
the nose, the second leads forward to the mouth, the third downward to
the trachea and lungs, the fourth downward and backward to the
stomach.

242. The OESOPHAGUS is a large membranous tube that extends behind the
trachea, the heart, and lungs, pierces the diaphragm, and terminates
in the stomach. It is composed of two membranes--an internal, or
mucous, and a muscular coat. The latter is composed of two sets of
fibres; one extends lengthwise, the other is arranged in circular
bands.

243. The STOMACH is situated in the left side of the abdomen,
immediately below and in contact with the diaphragm. It has two
openings; one connected with the oesophagus, called the _car´di-ac_
orifice; the other connected with the upper portion of the small
intestine, called the _py-lor´ic_ orifice. It is composed of three
coats, or membranes. The exterior or serous coat is very tough and
strong, and invests every part of this important organ. The middle, or
muscular coat is composed of two layers of muscular fibres, one set of
which is arranged longitudinally, the other circularly. The interior
coat is called the mucous, and is arranged in _ru´gæ_, (folds.) The
stomach is provided with a multitude of small glands, in which is
secreted the gastric fluid.

_Illustration._ The three coats of the stomach anatomically resemble
tripe, which is a preparation of the largest stomach of the cow or ox.
The outer coat is smooth and highly polished. The middle coat is
composed of minute threads, which are arranged in two layers. The
fibres of these layers cross each other. The inner coat is soft, and
presents many folds, usually named "the honey-comb."

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241. Describe the pharynx and the passages leading from it. 242. Give
the structure of the oesophagus. 243. Where is the stomach situated?
How many coats has it? Describe them. What article prepared for food
does the stomach resemble?

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[Illustration: Fig. 60. The inner surface of the stomach and duodenum. 1,
The lower portion of the oesophagus. 2, The opening through which the
food is passed into the stomach. 8, The stomach. 9, The opening through
which the food passes out of the stomach into the duodenum, or upper
portion of the small intestine. 10, 11, 14, The duodenum 12, 13, Ducts
through which the bile and pancreatic fluid pass into it. _a_, _b_, _c_,
The three coats of the stomach.]

244. The INTESTINES, or alimentary canal, are divided into two
parts--the _small_ and _large_. The small intestine is about
twenty-five feet in length, and is divided into three portions,
namely, the _Du-o-de´num_, the _Je-ju´num_, and the _Il´e-um_. The
large intestine is about five feet in length, and is divided into
three parts, namely, the _Cæ´cum_, the _Co´lon_, and the _Rec´tum_.
(Appendix D.)

245. The DUODENUM is somewhat larger than the rest of the small
intestine, and has received its name from being in length about the
breadth of twelve fingers. It commences at the pylorus, and ascends
obliquely backward to the under surface of the liver. It then descends
perpendicularly in front of the right kidney, and passes transversely
across the lower portion of the spinal column, behind the colon, and
terminates in the jejunum. The ducts from the liver and pancreas open
into the perpendicular portion, about six inches from the stomach.

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244. Explain fig. 60. What is the length of the small intestine, and
how is it divided? What is the length of the large intestine? Give its
divisions. 245. Describe the duodenum.

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246. The JEJUNUM is continuous with the duodenum. It is thicker than
the rest of the small intestine, and has a pinkish tinge.

247. The ILEUM is smaller, and thinner in texture, and somewhat paler,
than the jejunum. There is no mark to distinguish the termination of
the one or the commencement of the other. The ileum terminates near
the right haunch-bone, by a valvular opening into the colon at an
obtuse angle. This arrangement prevents the passing of substances from
the colon into the ileum. The jejunum and ileum are surrounded above
and at the sides by the colon.

248. The small intestine, like the stomach, has three coats. The
inner, or mucous coat is thrown into folds, or valves. In consequence
of this valvular arrangement, the mucous membrane is more extensive
than the other tissues, and gives a greater extent of surface with
which the aliment comes in contact. There are imbedded under this
membrane an immense number of minute glands, and it has a great number
of piles, like those upon velvet. For this reason, this membrane is
sometimes called the _vil´lous_ coat.

249. The CÆCUM is the blind pouch, or cul-de-sac, at the commencement
of the large intestine. Attached to its extremity is the _ap-pend´ix
verm-i-form´is_, (a long, worm-shaped tube.) It is from one to six
inches in length, and of the size of a goose-quill.

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What important ducts open into it? 246. Describe the jejunum. 247. The
ileum. 248. What is said of the coats of the intestines? Why is the
mucous membrane sometimes called the villous coat? 249. Describe the
cæcum.

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250. The COLON is divided into three parts--the _ascending_,
_transverse_, and _descending_. The ascending colon passes upward from
the right haunch-bone to the under surface of the liver. It then bends
inward, and crosses the upper part of the abdomen, below the liver and
stomach, to the left side under the name of the transverse colon. At
the left side, it turns, and descends to the left haunch-bone, and is
called the descending colon. Here it makes a peculiar curve upon
itself, which is called the _sig´moid flex´ure_.

[Illustration: Fig. 61. 1, 1, The duodenum. 2, 2, The small intestine. 3,
The junction of the small intestine with the colon. 4, The appendix
vermiformis. 5, The cæcum. 6, The ascending colon. 7, The transverse
colon. 8, The descending colon. 9, The sigmoid flexure of the colon. 10,
The rectum.]

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250. Describe the course of the divisions of the colon. Explain fig.
61.

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251. The RECTUM is the termination of the large intestine. The large
intestine has three coats, like the stomach and small intestine. The
longitudinal fibres of the muscular coat are collected into three
bands. These bands are nearly one half shorter than the intestine, and
give it a sacculated appearance, which is characteristic of the cæcum
and colon.

252. The LACTEALS are minute vessels, which commence in the villi,
upon the mucous surface of the small intestine. From the intestine
they pass between the membranes of the _mes´en-ter-y_ to small glands,
which they enter. The first range of glands collects many small
vessels, and transmits a few larger branches to a second range of
glands; and, finally, after passing through several successive ranges
of these glandular bodies, the lacteals, diminished in number and
increased in size, proceed to the enlarged portion of the thoracic
duct, into which they open. They are most numerous in the upper
portion of the small intestine.

253. The THORACIC DUCT commences in the abdomen, by a considerable
dilatation, which is situated in front of the lower portion of the
spinal column. From this point, it passes through the diaphragm, and
ascends to the lower part of the neck. In its ascent, it lies anterior
to the spine, and by the side of the aorta and oesophagus. At the
lower part of the neck, it makes a sudden turn downward and forward,
and terminates by opening into a large vein which passes to the heart.
The thoracic duct is equal in diameter to a goose-quill, and, at its
termination, is provided with a pair of semilunar valves, which
prevent the admission of venous blood into its cylinder.

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251. What is said of the arrangement of the fibres of the muscular
coat of the large intestine? 252. What are the lacteals? Give their
course from the mucous coat of the intestine to the thoracic duct.
253. Describe the course of the thoracic duct. How is the venous blood
prevented from passing into this duct?

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[Illustration: Fig. 62. A portion of the small intestine, lacteal
vessels, mesenteric glands, and thoracic duct. 1, The intestine. 2, 3, 4,
Mesenteric glands, through which the lacteals pass to the thoracic duct.
5, 6, The thoracic duct. 7, The point in the neck where it turns down to
enter the vein at 8. 9, 10, The aorta. 11, 12, Vessels of the neck. 13,
14, 15, The large veins that convey the blood and chyle to the heart. 16,
17, The spinal column. 18, The diaphragm, (midriff.)]

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Explain fig. 62. What is said respecting the mesenteric glands?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ The mesenteric glands, which are situated between two
layers of serous membrane (mesentery) that connects the small
intestine with the spinal column, occasionally become diseased in
childhood, and prevent the chyle from passing to the thoracic duct.
Children thus affected have a voracious appetite, and at the same time
are becoming more and more emaciated. The disease is called mesenteric
consumption.

254. The LIVER, a gland appended to the alimentary canal, is the
largest organ in the system, and weighs about four pounds. It is
situated in the right side, below the diaphragm, and is composed of
several lobes. Its upper surface is convex; its under, concave. This
organ is retained in its place by several ligaments. It performs the
double office of separating impurities from the venous blood, and of
secreting a fluid (bile) necessary to chylification. On the under
surface of the liver is a membranous sac, called the _gall-cyst_,
which is generally considered as a reservoir for the bile.

[Illustration: Fig. 63. The under surface of the liver. 1, The right
lobe. 2, The left. 3, 4, Smaller lobes. 10, The gall-bladder, or cyst,
lodged in its depression. 17, The notch on the posterior border, for the
spinal column.]

_Observation._ A good idea of the liver and intestines can be obtained
by examining these parts of a pig. In this animal, the sacs, or
pouches, of the large intestine are well defined.

255. The PANCREAS is a long, flattened gland, analogous to the
salivary glands. It is about six inches in length, weighs three or
four ounces, and is situated transversely across the posterior wall of
the abdomen, behind the stomach. A duct from this organ opens into the
duodenum.

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254. Describe the liver. 255. What is said of the pancreas?

  -=-=-=-=-=-=-=-=-=-=-=-=

256. The SPLEEN, (milt,) so called because the ancients supposed it to
be the seat of melancholy, is an oblong, flattened organ, situated in
the left side, in contact with the diaphragm, stomach, and the
pancreas. It is of a dark, bluish color, and is abundantly supplied
with blood, but has no duct which serves as an outlet for any
secretion. Its use is not well determined.

[Illustration: Fig. 64. The pancreas with its duct, through which the
pancreatic secretion passes into the duodenum.]

257. The OMENTUM (caul) consists of four layers of the serous
membrane, which descends from the stomach and transverse colon. A
quantity of adipose matter is deposited around its vessels, which
ramify through its structure. Its function is twofold in the animal
economy. 1st. It protects the intestines from cold. 2d. It facilitates
the movements of the intestines upon each other during their
vermicular, or worm-like action.

258. Every part of the digestive apparatus is supplied with arteries,
veins, lymphatics, and nervous filaments, from the ganglionic system
of nerves.

  -=-=-=-=-=-=-=-=-=-=-=-=

256. Why is the spleen so called? What is peculiar to this organ? 257.
Of what is the omentum composed? What is its use? 258. With what is
every part of the digestive apparatus supplied?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XIV.

PHYSIOLOGY OF THE DIGESTIVE ORGANS.


259. Substances received into the stomach as food, must necessarily
undergo many changes before they are fitted to form part of the animal
body. The solid portions are reduced to a fluid state, and those parts
that will nourish the body are separated from the waste material.

260. The first preparation of food for admission into the system,
consists in its proper mastication. The lips in front, the cheeks upon
the side, the soft palate, by closing down upon the base of the
tongue, retain the food in the mouth, while it is subjected to the;
process of _mas-ti-ca´tion_, (chewing.) The tongue rolls the mass
around, and keeps it between the teeth, while they divide the food to
a fineness suitable for the stomach.

261. While the food is in process of mastication, there is incorporated
with it a considerable amount of _sa-li´va_, (spittle.) This fluid is
furnished by the salivary glands, situated in the vicinity of the
mouth. The saliva moistens and softens the food, so that, when carried
into the pharynx. it is passed, with ease, through the oesophagus into the
stomach.

262. When the food has been properly masticated, (and in rapid eaters
when it is not,) the soft palate is raised from the base of the tongue
backward, so as to close the posterior opening through the nostrils.
By a movement of the muscles of the tongue, cheeks, and floor of the
mouth, simultaneous with that of the soft palate, the food is pressed
into the upper part of the pharynx.

  -=-=-=-=-=-=-=-=-=-=-=-=

259-272. _Give the physiology of the digestive organs._ 259. What is
necessary before food can nourish the body? 260. Describe how
mastication is performed. 261. Of what use is the saliva in the
process of mastication? 262. How is the food pressed into the
pharynx?

  -=-=-=-=-=-=-=-=-=-=-=-=

263. When in the pharynx, the food and drink are prevented from
passing into the trachea by a simple valve-like arrangement, called
the _ep-i-glot´tis_. The ordinary position of this little organ is
perpendicular, so as not to obstruct the passage of air into the
lungs; but in the act of swallowing, it is brought directly over the
opening of the trachea, called the _glot´tis_. The food, being forced
backward, passes rapidly over the epiglottis into the oesophagus,
where the circular band of muscular fibres above, contracts and forces
the food to the next lower band. Each band relaxes and contracts
successively, and thus presses the alimentary ball downward and onward
to the stomach.[8]

   [8] The process of deglutition may be comprehended by analyzing the
       operation of swallowing food or saliva.

_Observation._ If air is inhaled when the food or drink is passing
over the glottis, some portions of it may be carried into the larynx
or trachea. This produces violent spasmodic coughing, and most
generally occurs when an attempt is made to speak while masticating
food; therefore, never talk when the mouth contains food.

  -=-=-=-=-=-=-=-=-=-=-=-=

263. When the food is in the pharynx, how is it prevented from passing
into the trachea, or windpipe? Describe how it is passed into the
stomach? Give the observation. 264. Describe how the food in the
stomach is converted into chyme.

  -=-=-=-=-=-=-=-=-=-=-=-=

264. When the food reaches the stomach, the gastric glands are excited
to action, and they secrete a powerful solvent, called gastric juice.
The presence of food in the stomach also increases a contractile
action of the muscular coat, by which the position of the food is
changed from one part of this cavity to another. Thus the aliment is
brought in contact with the mucous membrane, and each portion of it
becomes saturated with gastric juice, by which it is softened, or
dissolved into a pulpy homogeneous mass, of a creamy consistence,
called _Chyme_. The food is not all converted into chyme at the same
time; but as fast as it is changed, it passes through the pyloric
orifice into the duodenum.

_Observation._ The gastric juice has the property of coagulating
liquid albuminous matter when mixed with it. It is this property of
rennet, which is an infusion of the fourth stomach of the calf, by
which milk is coagulated, or formed into "curd."

265. The CHYME is conveyed through the pyloric orifice of the stomach
into the duodenum. The chyme not only excites an action in the
duodenum, but also in the liver and pancreas. _Mucus_ is then secreted
by the duodenum, _bile_ by the liver, and _pancreatic fluid_ by the
pancreas. The bile and pancreatic fluid are conveyed into the
duodenum, and mixed with the chyme. By the action of these different
fluids, the chyme is converted into a fluid of a whitish color, called
_Chyle_, and into residuum.

_Observation._ The bile has no agency in the change through which
the food passes in the stomach. In a healthy condition of this
organ, no bile is found in it. The common belief, that the stomach
has a redundancy of this secretion, is erroneous. If bile is ejected
in vomiting, it merely shows, not only that the action of the
stomach is inverted, but also that of the duodenum. A powerful
emetic will, in this way, generally bring this fluid from the most
healthy stomach. A knowledge of this fact might save many a stomach
from the evils of emetics, administered on false impressions of
their necessity, and continued from the corroboration of these by
the appearance of bile, till derangement, and perhaps permanent
disease, are the consequences.

266. The CHYLE and residual matter are moved over the mucous surface
of the small intestine, by the action of its muscular coat. As the
chyle is carried along the tract of the intestine, it comes in contact
with the villi, where the lacteal vessels commence. These imbibe, or
take up, the chyle, and transfer it through the mesenteric glands into
the thoracic duct, through which it is conveyed into a large vein at
the lower part of the neck. In this vein the chyle is mixed with the
venous fluid. The residual matter is conveyed into the large
intestine, through which it is carried and excreted from the system.
(Appendix E.)

  -=-=-=-=-=-=-=-=-=-=-=-=

What peculiar property has gastric juice? 265. Where and how is chyme
converted into chyle? What is said in regard to the bile? 266. What
becomes of the chyle? Of the residuum?

  -=-=-=-=-=-=-=-=-=-=-=-=

267. In the process of digestion, the food is subjected to five
different changes. 1st. The chewing and admixture of the saliva with
the food; this process is called _mastication_.

268. 2d. The change through which the food passes in the stomach by
its muscular contraction, and the secretion from the gastric glands;
this is called _chymification_.

269. 3d. The conversion of the homogeneous chyme, by the agency of the
bile and pancreatic secretions, into a fluid of milk-like appearance;
this is _chylification_.

270. 4th. The absorption of the chyle by the lacteals, and its
transfer through them and the thoracic duct, into the subclavian vein
at the lower part of the neck.[9]

   [9] The chyle is changed by the lacteals and mesenteric glands, but
       the nature of this change is not, as yet, well defined or
       understood.

271. 5th. The separation and excretion of the residuum.

272. Perfection of the second process of digestion requires thorough
and slow mastication. The formation of proper chyle demands
appropriate mastication and chymification; while a healthy action of
the lacteals requires that all the anterior stages of the digestive
process be as perfect as possible. (Appendix F.)

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267. Recapitulate the five changes in the digestive process.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Note._ Let the pupil review the anatomy and physiology of the
digestive organs from figs. 62 and 65, or from anatomical outline
plate No. 5.

[Illustration: Fig. 65. An ideal view of the organs of digestion, opened
nearly the whole length. 1, The upper jaw. 2, The lower jaw. 3, The
tongue. 4, The roof of the mouth. 5, The oesophagus. 6, The trachea. 7,
The parotid gland. 8, The sublingual gland. 9, The stomach. 10, 10, The
liver. 11, The gall-cyst. 12, The duct that conveys the bile to the
duodenum, (13, 13.) 14, The pancreas. 15, 15, 15, 15, The small
intestine. 16, The opening of the small intestine into the large
intestine. 17, 18, 19, 20, The large intestine. 21, The spleen. 22, The
upper part of the spinal column.]



CHAPTER XV.

HYGIENE OF THE DIGESTIVE ORGANS.


273. It is a law of the system, that each organ is excited to healthy
and efficient action, when influenced by its appropriate stimulus.
Accordingly, nutrient food, that is adapted to the wants of the
system, imparts a healthy stimulation to the salivary glands during
the process of mastication. The food that is well masticated, and has
blended with it a proper amount of saliva, will induce a healthy
action in the stomach. Well-prepared chyme is the natural stimulus of
the duodenum, liver, and pancreas; pure chyle is the appropriate
excitant of the lacteal vessels.

274. The perfection of the digestive process, as well as the health of
the general system, requires the observance of certain conditions.
These will be considered under four heads:--1st. The _Quantity_ of
food that should be taken. 2d. Its _Quality_. 3d. The _Manner_ in
which it should be taken. 4th. The _Condition_ of the system when food
is taken.

275. The QUANTITY of food necessary for the system varies. Age,
occupation, temperament, temperature, habits, amount of clothing,
health and disease are among the circumstances which produce the
variation.

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273-330. _Give the hygiene of the digestive organs._ 273. Give a law
of the system. What is the appropriate stimulus of the salivary glands
during mastication? Of the stomach? Of the duodenum? Of the lacteal
vessels? 274. What does the perfection of the digestive organs
require? 275. What exert an influence on the quantity of food
necessary for the system?

  -=-=-=-=-=-=-=-=-=-=-=-=

276. _The child and youth require food to promote the growth of the
different parts of the body._ The more rapid the growth of the child,
the greater the demand for food. This accounts for the keen appetite
and vigorous digestion in childhood. When the youth has attained his
full growth, this necessity for nutriment ceases; after this period of
life, if the same amount of food is taken, and there is no increase of
labor or exertion, the digestive apparatus will become diseased, and
the vigor of the whole system diminished.

_Observation._ When the body has become emaciated from want of
nutriment, either from famine or disease, there is an increased demand
for food. This may be gratified with impunity until the individual has
regained the usual size, but repletion should be avoided.

277. _Food is required to repair the waste, or loss of substance
that attends action._ In every department of nature, waste, or loss of
substance, attends and follows action. When an individual increases
his exercise,--changes from light to severe labor,--or the inactive
and sedentary undertake journeys for pleasure, the fluids of the
system circulate with increased energy. The old and exhausted
particles of matter are more rapidly removed through the action of
the vessels of the skin, lungs, kidneys, and other organs, and
their places are filled with new atoms, deposited by the small
blood-vessels.

278. As the chyle supplies the blood with the newly vitalized
particles of matter, there is, consequently, an increased demand for
food. This want of the system induces, in general, a sensation of
hunger or appetite, which may be regarded as an indication of the
general state of the body. The sympathy that exists throughout the
system accords to the stomach the power of making known this state to
the nervous system, and, if the functions of this faithful monitor
have not been impaired by disease, abuse, or habit, the call is
imperious, and should be regarded.

  -=-=-=-=-=-=-=-=-=-=-=-=

276. At what age is the appetite keen and the digestion vigorous? Why?
What is said in regard to the quantity of food when the youth has
attained his growth? What exception, as given in the observation? 277.
Give another demand for food. What effect has increased exercise upon
the system? 278. How are the new particles of matter supplied? What
does this induce?

  -=-=-=-=-=-=-=-=-=-=-=-=

279. _When exercise or labor is lessened, the quantity of food should
be diminished._ When a person who has been accustomed to active
exercise, or even hard manual labor, suddenly changes to an employment
that demands less activity, the waste attendant on action will be
diminished in a corresponding degree; hence the quantity of food
should be lessened in nearly the same proportion as the amount of
exercise is diminished. If this principle be disregarded, the tone of
the digestive organs will be impaired, and the health of the system
enfeebled.

280. This remark is applicable to those students who have left
laborious employments to attend school. Although the health is firm,
and the appetite keen from habit, yet every pupil should practise some
self-denial, and not eat as much as the appetite craves, the first
week of the session. After some days, the real wants of the system
will generally be manifested by a corresponding sensation of hunger.

_Observation._ It is a common observation that in academies and
colleges, the older students from the country, who have been
accustomed to hard manual labor, suffer more frequently from defective
digestion and impaired health than the younger and feebler students
from the larger towns and cities.

281. _Food is essential in maintaining a proper temperature of the
system._ The heat of the system, at least in part, is produced in the
minute vessels of the several organs, by the union of oxygen with
carbon and hydrogen, which the food and drink contain. The amount of
heat generated, is greatest when it is most rapidly removed from the
system, which occurs in cold weather. This is the cause of the system
requiring more food in winter than summer.

  -=-=-=-=-=-=-=-=-=-=-=-=

279. Why should the quantity of food be diminished when the exercise
is lessened? What effect if this principle be disregarded? 280. To
what class is this remark applicable? What is often observed among
students in academies and colleges? 281. State another demand for
food. What is one source of heat in the body?

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_Observation._ Persons that do not have food sufficient for the
natural wants of the system, require more clothing than those who are
well fed.

282. The last-mentioned principle plainly indicates the propriety and
necessity of lessening the quantity of food as the warm season
approaches. Were this practised, the tone of the stomach and the vigor
of the system would continue unimpaired, the "season complaints" would
be avoided, and the "strengthening bitters" would not be sought to
create an appetite.

_Observation._ Stable-keepers and herdsmen are aware of the fact, that
as the warm season commences, then animals require less food. Instinct
teaches these animals more truly, in this particular, than man allows
reason to guide him.

283. _The quantity of food should have reference to the present
condition of the digestive organs._ If they are weakened or diseased,
so that but a small quantity of food can be properly digested or
changed, that amount only should be taken. Food does not invigorate
the system, except it is changed, as has been described in previous
paragraphs.

_Observation._ When taking care of a sick child, the anxiety of the
mother and the sufferings of the child may induce her to give food
when it would be highly injurious. The attending physician is the only
proper person to direct what quantity should be given.

  -=-=-=-=-=-=-=-=-=-=-=-=

Why do we eat more in the winter than in the summer? What practical
observation is given? 282. Why should the quantity of food be lessened
as warm weather commences? What would be avoided if this principle
were obeyed? 283. Why should the present condition of the digestive
organs be regarded in reference to the quantity of food? Mention an
instance in which it would be injudicious to give food.

  -=-=-=-=-=-=-=-=-=-=-=-=

284. _The quantity of food is modified, in some degree, by habit._ A
healthy person, whose exercise is in pure air, may be accustomed to
take more food than is necessary. The useless excess is removed from
the system by the waste outlets, as the skin, lungs, liver, kidneys,
&c. In such cases, if food is not taken in the usual quantity, there
will be a feeling of emptiness, if not of hunger, from the want of the
usual distention of the stomach. This condition of the digestive
organs may be the result of disease, but it is more frequently
produced by inordinate daily indulgence in eating, amounting almost to
gluttony.

285. _Large quantities of food oppress the stomach, and cause general
languor of the whole body._ This is produced by the extra demands made
on the system for an increased supply of blood and nervous fluid to
enable the stomach to free itself of its burden. Thus, when we intend
to make any extraordinary effort, mental or physical, at least for one
meal, we should eat less food than usual, rather than a greater
quantity.

286. _No more food should be eaten than is barely sufficient to
satisfy the appetite._ Nor should appetite be confounded with taste.
The one is a natural desire for food to supply the wants of the
system; the other is an artificial desire merely to gratify the
palate.

287. Although many things may aid us in determining the quantity of
food proper for an individual, yet there is no certain guide in all
cases. It is maintained by some, that the sensation of hunger or
appetite is always an indication of the want of food, while the
absence of this peculiar sensation is regarded as conclusive evidence
that aliment is not demanded. This assertion is not correct, as an
appetite may be created for food by condiments and gormandizing, which
is as artificial and as morbid as that which craves tobacco or ardent
spirits. On the other hand, a structural or functional disease of the
brain may prevent that organ from taking cognizance of the sensations
of the stomach, when the system actually requires nourishment.
Observation shows, that disease, habit, the state of the mind, and
other circumstances, exert an influence on the appetite.

  -=-=-=-=-=-=-=-=-=-=-=-=

284. Show the effect of habit upon the quantity of food that is eaten.
What is said in regard to inordinate eating? 285. What is the effect
of eating large quantities of food? What suggestion when an
extraordinary effort, either mental or physical, is to be made? 286.
How much food should generally be eaten? 287. What is the assertion of
some persons relative to the quantity of food necessary for the
system?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Dr. Beaumont noticed, in the experiments upon Alexis
St. Martin, that after a certain amount of food was converted into
chyme, the gastric juice ceased to ooze from the coats of the stomach.
Consequently, it has been inferred by some writers on physiology, that
the glands which supply the gastric fluid, by a species of instinctive
intelligence, would only secrete enough fluid to convert into chyme
the aliment needed to supply the real wants of the system. What are
the reasons for this inference? There is no evidence that the gastric
glands possess instinctive intelligence, and can there be a reason
adduced, why they may not be stimulated to extra functional action as
well as other organs, and why they may not also be influenced by
habit?

288. While all agree that the remote or predisposing cause of hunger
is, usually, a demand of the system for nutrient material, the
proximate or immediate cause of the sensation of hunger is not clearly
understood. Some physiologists suppose that it is produced by an
engorged condition of the glands of the stomach which supply the
gastric juice; while others maintain that it depends on a peculiar
condition of the nervous system.

289. The QUALITY of the food best adapted to the wants of the system
is modified by many circumstances. There are many varieties of food,
and these are much modified by the different methods of preparation.
The same kind of food is not equally well adapted to different
individuals, or to the same individual in all conditions; as vocation,
health, exposure, habits of life, season, climate, &c., influence the
condition of the system.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does observation show? 288. What is said of the causes of
hunger? 289. Why is not the same kind of food adapted to different
individuals?

  -=-=-=-=-=-=-=-=-=-=-=-=

290. All articles of food may be considered in two relations: 1st, As
nutritive. 2d, As digestible. Substances are nutritious in proportion
to their capacity to yield the elements of chyle, of which carbon,
oxygen, hydrogen, and nitrogen are the most essential; they are
digestible in proportion to the facility with which they are acted
upon by the gastric juice. These properties should not be confounded
in the various articles used for food.

291. As a "living body has no power of forming elements, or of
converting one elementary substance into another, it therefore follows
that the elements of which the body of an animal is composed must be
in the food." (Chap. III.) Of the essential constituents of the human
body, carbon, hydrogen, oxygen, and nitrogen are the most important,
because they compose the principal part of the animal body; while the
other elements are found in very small proportions, and many of them
only in a few organs of the system. (Appendix G.)

_Observation._ Nitrogen renders food more stimulating, particularly if
combined with a large quantity of carbon, as beef. Those articles that
contain the greatest amount of the constituent elements of the system
are most nutritious. As milk and eggs contain all the essential
elements of the human system, so they are adapted to almost universal
use, and are highly nutritious.

  -=-=-=-=-=-=-=-=-=-=-=-=

290. In what proportion are substances nutritious? Digestible? Why
does beef stimulate the system? What is said of milk and eggs?

  -=-=-=-=-=-=-=-=-=-=-=-=

292. The following table, by Pereira, in his treatise on Food and
Diet may aid the student in approximating to correct conclusions of
the quantity of nutriment in different kinds of food, and its
adaptation to the wants of the system.

TABLE,

SHOWING THE AVERAGE QUANTITY OF DRY, OR SOLID MATTER, CARBON,
NITROGEN, AND MOISTURE, IN DIFFERENT ARTICLES OF DIET.

 -------------------+---------+---------+-----------+------------
 One hundred Parts. |  Dry    | Carbon. | Nitrogen. | Water
                    | Matter. |         |           |
 -------------------+---------+---------+-----------+------------
 Arrowroot,         |  81.8   | 36.4    |           |  18.2
 Beans,             |  85.89  | 38.24   |           |  14.11
 Beef, fresh,       |  25     | 12.957  |   3.752   |  75
 Bread, rye,        |  67.79  | 30.674  |           |  32.21
 Butter,            | 100     | 65.6    |           |
 Cabbage,           |   7.7   |         |   0.28    |  92.3
 Carrot,            |  12.4   |         |   0.30    |  87.6
 Cherries,          |  25.15  |         |           |  74.85
 Chickens,          |  22.7   |         |           |  77.3
 Codfish,           |  20     |         |           |  80
 Cucumbers,         |   2.86  |         |           |  97.14
 Eggs, whites,      |  20     |         |           |  80
 ----, yolk,        |  46.23  |         |           |  53.77
 Lard, hog's,       | 100     | 79.098  |           |
 Milk, cow's,       |  12.98  |         |           |  87.02
 Oats,              |  79.2   | 40.154  |   1.742   |  20.8
 Oatmeal,           |  93.4   |         |           |   6.6
 Olive-oil,         | 100     | 77.50   |           |
 Oysters,           |  12.6   |         |           |  87.4
 Peaches,           |  19.76  |         |           |  80.24
 Pears,             |  16.12  |         |           |  83.88
 Peas,              |  84     | 35.743  |           |  16
 Plums, greengage,  |  28.90  |         |           |  71.10
 Potatoes,          |  24.1   | 10.604  |   0.3615  |  75.9
 Rye,               |  83.4   | 38.530  |   1.417   |  16.6
 Suet, mutton,      | 100     | 78.996  |           |
 Starch, potato,    |  82     | 36.44   |           |  18
 ----, wheat,       |  85.2   | 37.5    |           |  14.8
 Sugar, maple,      |         | 42.1    |           |
 ----, refined,     |         | 42.5    |           |
 ----, brown,       |         | 40.88   |           |
 Turnips,           |  7.5    |  3.2175 |   0.1275  |  92.5
 Veal, roasted,     |         | 52.52   |  14.70    |
 Wheat,             | 85.5    | 39.415  |   1.966   |  14.5
 -------------------+---------+---------+-----------+------------

_Note._ Let the pupil mention those articles of food that are
most nutritious, from a review of this table, and the last four
paragraphs.

293. Those articles that do not contain the essential elements of the
system should not be used as exclusive articles of diet. This
principle has been, and may be illustrated by experiment. Feed a dog
with pure sugar, or olive-oil, (articles that contain no nitrogen,)
for several weeks, and the evil effects of non-nitrogenous nutriment
will be manifested. At first, the dog will take his food with avidity,
and seem to thrive upon it; soon this desire for food will diminish,
his body emaciate, his eye become ulcerated, and in a few weeks he
will die; but mix bran or sawdust with the sugar or oil, and the
health and vigor of the animal will be maintained for months. A
similar phenomenon will be manifested, if grain only be given to a
horse, without hay, straw, or material of like character. (Appendix
H.)

294. Some articles of food contain the elements of chyle in great
abundance, yet afford but little nutriment, because they are difficult
of digestion; while other articles contain but a small quantity of
these elements, and afford more nourishment, because they are more
easily affected by the digestive process.

  -=-=-=-=-=-=-=-=-=-=-=-=

293. How has the effect of non-nitrogenous nutriment been illustrated?
294. Why do some articles of food that contain the elements of chyle
afford but little nutriment? Why do articles that contain a small
quantity of these elements afford more nourishment? 295. How was the
time required for digesting different articles of food ascertained?

  -=-=-=-=-=-=-=-=-=-=-=-=

295. The following table exhibits the general results of experiments
made on Alexis St. Martin, by Dr. Beaumont, when he endeavored to
ascertain the time required for the digestion of different articles of
food.[10] The stomach of St. Martin was ruptured by the bursting of a
gun. When he recovered from the effects of the accident under the
surgical care of Dr. Beaumont, the stomach became adherent to the
side, with an external aperture. Nature had formed a kind of valve,
which closed the aperture from the interior, and thus prevented the
contents of the stomach from escaping; but on pushing it aside, the
process of digestion could be seen. Through this opening, the
appearance of the coats of the stomach and food, at different stages
of digestion, were examined.

  [10] The time required for the digestion of the different articles of
       food might vary in other persons; and would probably vary in
       the same individual at different periods, as the employment,
       health, season, &c., exert a modifying influence.

TABLE,

SHOWING THE MEAN TIME OF DIGESTION OF THE DIFFERENT
ARTICLES OF DIET.

 -----------------------------+--------------+--------
 Articles.                    | Preparation. | Time
                              |              | h. m.
 -----------------------------+--------------+--------
 Apples, sour, hard,          | Raw,         | 2 50
 Apples, sour, mellow,        | Raw,         | 2
 Apples, sweet, do.,          | Raw,         | 1 30
 Bass, striped, fresh,        | Broiled,     | 3
 Beans, pod,                  | Boiled,      | 2 30
 Beef, fresh, lean, rare,     | Roasted,     | 3
 Beef, fresh, lean, dry,      | Roasted,     | 3 30
 Beef steak,                  | Broiled,     | 3
 Beef, with salt only,        | Boiled,      | 3 36
 Beef, with mustard,          | Boiled,      | 3 10
 Beef, fresh, lean,           | Fried,       | 4
 Beef, old, hard, salted,     | Boiled,      | 4 15
 Beets,                       | Boiled,      | 3 45
 Bread, wheat, fresh,         | Baked,       | 3 30
 Bread, corn,                 | Baked,       | 3 15
 Butter,                      | Melted,      | 3 30
 Cabbage head,                | Raw,         | 2 30
 Cabbage, with vinegar,       | Raw,         | 2
 Cabbage,                     | Boiled,      | 4 30
 Cake, sponge,                | Baked,       | 2 30
 Carrot, orange,              | Boiled,      | 3 15
 Catfish,                     | Fried,       | 3 30
 Cheese, old, strong,         | Raw,         | 3 30
 Chicken, full-grown,         | Fricas'd,    | 2 45
 Codfish, cured, dry,         | Boiled,      | 2
 Corn, green, & beans,        | Boiled,      | 3 45
 Corn bread,                  | Baked,       | 3 15
 Corn cake,                   | Baked,       | 3
 Custard,                     | Baked,       | 2 45
 Dumpling, apple,             | Boiled,      | 3
 Ducks, domesticated,         | Roasted,     | 4
 Ducks, wild,                 | Roasted,     | 4 30
 Eggs, fresh,                 | Boiled hard, | 3 30
 Eggs, fresh,                 | Boiled soft, | 3
 Eggs, fresh,                 | Fried,       | 3 30
 Eggs, fresh,                 | Raw,         | 2
 Flounder, fresh,             | Fried,       | 3 30
 Fowl, domestic,              | Boiled,      | 4
 Fowl, domestic,              | Roasted,     | 4
 Goose,                       | Roasted,     | 2 30
 Lamb, fresh,                 | Broiled,     | 2 30
 Liver, beef's, fresh,        | Broiled,     | 2
 Meat hashed with vegetables, | Warm'd,      | 2 30
 Milk,                        | Boiled,      | 2
 Milk,                        | Raw,         | 2 15
 Mutton, fresh,               | Roasted,     | 3 15
 Mutton, fresh,               | Broiled,     | 3
 Mutton, fresh,               | Boiled,      | 3
 Oysters, fresh,              | Raw,         | 2 55
 Oysters, fresh,              | Roasted,     | 3 15
 Oysters, fresh,              | Stewed,      | 3 30
 Parsnips,                    | Boiled,      | 2 30
 Pig, sucking,                | Roasted,     | 2 30
 Pigs' feet, soused,          | Boiled,      | 1
 Pork, fat and lean,          | Roasted,     | 5 15
 Pork, recently salted,       | Boiled,      | 4 30
 Pork, recently salted,       | Fried,       | 4 15
 Pork, recently salted,       | Broiled,     | 3 15
 Pork, recently salted,       | Raw,         | 3
 Pork, steak,                 | Broiled,     | 3 15
 Potatoes, Irish,             | Boiled,      | 3 30
 Potatoes, Irish,             | Baked,       | 2 30
 Rice,                        | Boiled,      | 1
 Sago,                        | Boiled,      | 1 45
 Salmon, salted,              | Boiled,      | 4
 Sausage, fresh,              | Broiled,     | 3 20
 Soup, beef, vegetables, and  | Boiled,      | 4
     bread,                   |              |
 Soup, chicken,               | Boiled,      | 3
 Soup, mutton,                | Boiled,      | 3 30
 Soup, oyster,                | Boiled,      | 3 30
 Suet, beef, fresh,           | Boiled,      | 5 30
 Suet, mutton,                | Boiled,      | 4 30
 Tapioca,                     | Boiled,      | 2
 Tripe, soused,               | Boiled,      | 1
 Trout, salmon, fresh,        | Boiled,      | 1 30
 Trout, salmon, fresh,        | Fried,       | 1 30
 Turkey, domesticated,        | Roasted,     | 2 30
 Turkey,                      | Boiled,      | 2 25
 Turkey, wild,                | Roasted,     | 2 18
 Turnips, flat,               | Boiled,      | 3 30
 Veal, fresh,                 | Broiled,     | 4
 Veal, fresh,                 | Fried,       | 4 30
 Venison steak,               | Broiled,     | 1 35
 -----------------------------+--------------+--------

296. In view of this table, the question may be suggested, Is that
article of food most appropriate to the system which is most easily
and speedily digested? To this it may be replied, that the stomach is
subject to the same law as the muscles and other organs; exercise,
within certain limits, strengthens it. If, therefore, we always eat
those articles most easily digested, the digestive powers will be
weakened; if over-worked, they will be exhausted. Hence the kind and
amount of food should be adapted to the maintenance of the digestive
powers, and to their gradual invigoration when debilitated.

_Observation._ Food that is most easily digested is not always most
appropriate to a person convalescing from disease. If the substance
passes rapidly through the digestive process, it may induce a
recurrence of the disease. Thus the simple preparations which are not
stimulating, as water-gruel, are better for a sick person than the
more digestible beef and fish.

297. The question is not well settled, whether animal or vegetable
food is best adapted to nourish man. There are nations, particularly
in the torrid zone, that subsist, exclusively, on vegetables; while
those of the frigid zone feed on fish or animal food. In the temperate
zone, among civilized nations, a mixed diet is almost universal. When
we consider the organization of the human system, the form and
arrangement of the teeth, the structure of the stomach and intestines,
we are led to conclude, that both animal and vegetable food is
requisite, and that a mixed diet is most conducive to strength,
health, and long life.

  -=-=-=-=-=-=-=-=-=-=-=-=

296. How is the question answered, whether that article is most
appropriate to the system which is most easily digested? Give
observation. 297. What is said of the adaptation of animal and
vegetable food to man?

  -=-=-=-=-=-=-=-=-=-=-=-=

298. _The food should be adapted to the distensible character of the
stomach and alimentary canal._ The former will be full, if it contain
only a gill; it may be so distended as to contain a quart. The same is
true of the intestines. If the food is concentrated, or contains the
quantity of nutriment which the system requires, in small bulk, the
stomach and intestines will need the stimulation of distention and
friction, which is consequent upon the introduction and transit of the
innutritious material into and through the alimentary canal. If the
food is deficient in innutritious matter, the tendency is, to produce
an inactive and diseased condition of the digestive organs. For this
reason, nutrient food should have blended with it innutritious
material. Unbolted wheat bread is more healthy than hot flour cakes;
ripe fruits and vegetables than rich pies, or jellies.

_Observation._ 1st. The observance of this rule is of more importance
to students, sedentary mechanics, and those individuals whose
digestive apparatus has been enfeebled, than to those of active habits
and firm health.

2d. The circumstance that different articles of food contain different
proportions of waste, or innutritious matter, may be made practically
subservient in the following way: If, at any particular season of the
year, there is a tendency to a diarrhoea, an article that contains a
small proportion of waste should be selected for food; but, if there
is a tendency to an inactive or costive condition of the intestinal
canal, such kinds of food should be used as contain the greatest
proportion of waste, as such articles are most stimulating to the
digestive organs, and, consequently, most laxative.

299. _In the selection of food, the influence of season and climate
should be considered._ Food of a highly stimulating character may be
used almost with impunity during the cold weather of a cold climate;
but in the warm season, and in a warm climate, it would be very
deleterious. Animal food, being more stimulating than vegetable, can
be eaten in the winter but vegetable food should be used more freely
in the spring and summer.

  -=-=-=-=-=-=-=-=-=-=-=-=

298. What is said of the distensible character of the stomach and
alimentary canal? What is the effect of eating highly concentrated
food? Why is the unbolted wheat bread more healthy than flour cakes?
Give observation 1st. Observation 2d. 299. What kind of food is
adapted to cold weather? To warm weather?

  -=-=-=-=-=-=-=-=-=-=-=-=

300. _The influence of food on the system is modified by the age of
the individual._ The organs of a child are more sensitive and
excitable than those of a person advanced in years. Therefore a
vegetable diet would be most appropriate for a child, while
stimulating animal food might be conducive to the health of a person
advanced in life.

_Observation._ When the digestive organs are highly impressible or
diseased, it is very important to adopt a nutritious, unstimulating,
vegetable diet, as soon as the warm season commences.

301. _Habit is another strong modifying influence._ If a person has
been accustomed to an animal or vegetable diet, and there is a sudden
change from one to the other, a diseased condition of the system,
particularly of the digestive apparatus, usually follows. When it is
necessary to change our manner of living, it should be done
gradually.[11]

  [11] The system is gradually developed, and all changes of food,
       apparel, labor, exercise, or position, should be gradual. Even
       a change from a bad to a good habit, on this principle, should
       be gradual.

302. _Some temperaments require more stimulating food than others._ As
a general rule, those persons whose sensations are comparatively
obtuse, and movements slow, will be benefited by animal food; while
those individuals whose constitutions are highly impressible, and
whose movements are quick and hurried, require a nutritious and
unstimulating vegetable diet.

  -=-=-=-=-=-=-=-=-=-=-=-=

300. What kinds of food are appropriate to old age? Why? What kinds to
childhood? Why? 301. What is the effect when there is a sudden change
from a vegetable to an animal diet? How should all changes of the
system be made? 302. Do different temperaments require different kinds
of food? What general rule is given?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XVI.

HYGIENE OF THE DIGESTIVE ORGANS, CONTINUED.


303. The MANNER in which food should be taken is of much practical
importance; upon it the health of the digestive organs measurably
depends. But few circumstances modify the proper manner of taking
food, or should exercise any controlling influence.

304. _Food should be taken at regular periods._ The interval between
meals should be regulated by the character of the food, the age,
health, exercise, and habits of the individual. The digestive process
is more energetic and rapid in the young, active, and vigorous, than
in the aged, indolent, and feeble; consequently, food should be taken
more frequently by the former than by the latter class.

305. In some young and vigorous persons, food may be digested in one
hour; in other persons, it may require four hours or more. The average
time, however, to digest an ordinary meal, will be from two to four
hours. In all instances, the stomach will require from one to three
hours to recruit its exhausted powers after the labor of digesting a
meal before it will again enter upon the vigorous performance of its
duties.

306. _Food should not be taken too frequently._ If food is taken
before the stomach has regained its tone and energy by repose, the
secretion of the gastric juice, and the contraction of the muscular
fibres, will be imperfect. Again, if food is taken before the
digestion of the preceding meal has been completed, the effects will
be still worse, because the food partially digested becomes mixed with
that last taken. Therefore the interval between each meal should be
long enough for the whole quantity to be digested, and the time of
repose should be sufficient to recruit the exhausted organs. The
feebler the person and the more debilitated the stomach, the more
important to observe the above directions.

  -=-=-=-=-=-=-=-=-=-=-=-=

303. Why is it important that we regard the manner of taking our food?
304. How should the intervals between meals be regulated? 305. What is
the average time required to digest an ordinary meal? 306. Why should
not food be taken too frequently?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ In the feeding of infants, as well as in supplying food
to older children, the preceding suggestions should always be
regarded. The person who has been confined by an exhausting sickness,
should most scrupulously regard this rule, if he wishes to regain his
strength and flesh with rapidity. As the rapidity of the digestive
process is less in students and individuals who are engaged in
sedentary employments, than in stirring agriculturists, the former
class are more liable to take food too frequently than the latter,
while its observance is of greater importance to the sedentary artisan
than to the lively lad and active farmer.

307. _Food should be well masticated._ All solid aliments should be
reduced to a state of comparative fineness, by the teeth, before it is
swallowed; the gastric fluid of the stomach will then blend with it
more readily, and act more vigorously in reducing it to chyme. The
practice of swallowing solid food, slightly masticated, or "bolting"
it down, tends to derange the digestive process and impair the
nutrition of the system.

308. _Mastication should be moderate, not rapid._ In masticating food,
the salivary glands are excited to action, and some time must elapse
before they can, secrete saliva in sufficient quantities to moisten
it. If the aliment is not supplied with saliva, digestion is retarded;
besides, in rapid eating, more food is generally consumed than the
system demands, or can be easily digested. Laborers, as well as men of
leisure, should have ample time for taking their meals. Imperfect
mastication is a prevailing cause of indigestion.

  -=-=-=-=-=-=-=-=-=-=-=-=

What persons would be benefited by observing the preceding remarks?
307. Why should food be well masticated? What is the effect of
"bolting down" food? 308. How should mastication be performed? Why?

  -=-=-=-=-=-=-=-=-=-=-=-=

309. _Food should be masticated and swallowed without drink._ As the
salivary glands supply fluid to moisten the dry food, the use of tea,
coffee, water, or any other fluid, is not demanded by nature's laws
while taking a meal. One objection to "washing down" the food with
drink is, the aliment is moistened, not with the saliva, but with the
drink. This tends to induce disease, not only in the salivary organs,
by leaving them in a state of comparative inactivity, but in the
stomach, by the deficiency of the salivary stimulus. Another is, large
quantities of fluids, used as drinks, give undue distention to the
stomach, and lessen the energy of the gastric juice by its dilution,
thus retarding digestion. Again, drinks taken into the stomach must be
removed by absorption before the digestion of other articles is
commenced.

_Observation._ Were it customary not to place drinks on the table
until the solid food is eaten, the evil arising from drinking too much
at meals would be obviated. The horse is never known to leave his
provender, nor the ox his blade of grass, to wash it down; but many
persons, from habit rather than thirst, drink largely during meals.

310. The peculiar sensation in the mouth and fauces, called thirst,
may not always arise from the demand for fluids to increase the
_serum_ (water) of the blood, as in the desire for drink attendant on
free perspiration, for then, pure water or some diluent drink is
absolutely necessary; but it may be the result of fever, or local
disease of the parts connected with the throat. In many instances,
thirst may be allayed by chewing some hard substance, as a dry
cracker. This excites a secretion from the salivary glands, which
removes the disagreeable sensation. In thirst, attendant on a heated
condition of the system, this practice affords relief, and is safe;
while the practice of drinking large quantities of cold fluids, is
unsafe, and should never be indulged.

  -=-=-=-=-=-=-=-=-=-=-=-=

Why should all persons have ample time for eating? 309. Why are drinks
not necessary while masticating food? Give the objections to "washing
down" food. What observation relative to drink? 310. Does the
sensation of thirst always arise from a real want of the system?

  -=-=-=-=-=-=-=-=-=-=-=-=

311. _Food or drink should not be taken when very hot._ When food or
drink is taken hot, the vessels of the mucous membrane of the gums,
mouth, and stomach are unduly stimulated for a short time; and this is
followed by reaction, attended by a loss of tone, and debility of
these parts. This practice is a fruitful cause of spongy gums, decayed
teeth, sore mouth, and indigestion.

312. _Food or drink should not be taken very cold._ If a considerable
quantity of very cold food or liquid be taken immediately into the
stomach, the health will be endangered, and the tone of the system
will be impaired, from the sudden abstraction of heat from the coats
of the stomach, and from surrounding organs, to impart warmth to the
cold food or drink. This arrests the digestive process, and the food
is retained in the stomach too long, and causes oppression and
irritation. Consequently, food and drink that are moderately heated
are best adapted to the natural condition of the digestive apparatus.

_Observation._ Food of an injurious quality, or taken in an improper
manner, affects the inferior animals as well as man. The teeth of cows
that are closely penned in cities, and are fed on distillery slops, or
the unhealthy slops and remnants of kitchens, decay and fall out in
about two years. Can the milk of such diseased animals be healthy--the
proper nourishment for children?

  -=-=-=-=-=-=-=-=-=-=-=-=

Give instances when it does and when it does not. 311. Why should not
food or drink be taken hot? 312. Why should they not be taken cold?
Show some of the effects of improper food upon the inferior animals.

  -=-=-=-=-=-=-=-=-=-=-=-=

313. The CONDITION of the system should be regarded when food is
taken. This is necessary, as the present and ulterior condition of the
digestive apparatus is strongly influenced by the state of the other
organs of the system.

314. _Food should not be taken immediately after severe exertion,
either of the body or mind._ For all organs in action require and
receive more blood and nervous fluid, than when at rest. This is true
of the brain, muscles, and vocal organs, when they have been actively
exercised. The increased amount of fluid, both sanguineous and
nervous, supplied to any organ during extra functional action, is
abstracted from other parts of the system. This enfeebles and
prostrates the parts that supply the blood and nervous fluid to the
active organ. Again, when any organ has been in vigorous action for a
few hours, some time will elapse before the increased action of the
arteries and nerves abates, and a due supply of fluids is transmitted
to other organs, or an equilibrium of action in the system is
reëstablished.

315. Thus food should not be taken immediately after severe mental
labor, protracted speaking, continued singing, or laborious manual
toil; as the digestive organs will be in a state of comparative
debility, and consequently unfit to digest food. From thirty to sixty
minutes should elapse, after the cessation of severe employment,
before food is taken. This time may be spent in cheerful amusement or
social conversation.

_Observation._ The practice of students and accountants going
immediately from severe mental labor to their meals, is a pernicious
one, and a fruitful cause of indigestion and mental debility. The
custom of farmers and mechanics hurrying from their toil to the
dinner-table, does much to cause dyspepsia and debility among these
classes in community.

  -=-=-=-=-=-=-=-=-=-=-=-=

313. Should the condition of the system be regarded in taking food?
314. When should food not be taken? Why? What is the result when an
organ has been in vigorous action? 315. After the cessation of severe
toil, how much time should expire before eating? What is one cause of
indigestion among students and accountants?

  -=-=-=-=-=-=-=-=-=-=-=-=

316. _Severe mental or manual toil should not be entered upon
immediately after eating._ As there is an increased amount of blood
and nervous fluid supplied to the stomach and alimentary canal during
the digestion of food, a deficiency exists in other organs. This is
evinced by a slight paleness of the skin, and a disinclination to
active thought and exercise. Under such circumstances, if either the
mind, vocal organs, or muscles are called into energetic action, there
will be an abstraction of the necessary amount of blood and nervous
fluid from the stomach, and the process of digestion will be arrested.
This will not only cause disease of the digestive organs, but chyle
will not be formed, to nourish the system.

_Illustration._ An English gentleman fed two dogs upon similar
articles of food. He permitted one to remain quiet in a dark room; the
other he sent in pursuit of game. At the expiration of one hour, he
had both killed. The stomach of the dog that had remained quiet was
nearly empty. The food had been properly changed and carried forward
into the alimentary canal. In the stomach of the dog that had used his
muscles in chasing game, the aliment remained nearly unaltered.

317. The same principle may be applied to the action of the organs of
man. If his mind or muscles act intensely soon after eating, the
stomach will not be sufficiently stimulated by blood and nervous fluid
to change the food in a suitable period. The Spanish practice of
having a "siesta," or sleep after dinner, is far better than the
custom of the Anglo-Saxon race, who hurry from their meals to the
field, shop, or study, in order to save time, which, in too many
instances, is lost by a sense of oppression and suffering which soon
follows.

  -=-=-=-=-=-=-=-=-=-=-=-=

316. Why should not severe manual or mental exertion be made
immediately after eating? State the illustration. 317. May this
principle be applied to the action of the human stomach? What is said
of the Spanish custom of resting after dinner?

  -=-=-=-=-=-=-=-=-=-=-=-=

318. In some instances of good health, the infringement of this
organic law may seem to pass with impunity, but Nature, though
lenient, sooner or later asserts her claims. The practice of the
Spaniard may be improved by indulging, for an hour before resuming
toil, in moderate exercise of the muscular system, conjoined with
agreeable conversation and a hearty laugh, as this facilitates
digestion, and tends to "shake the cobwebs from the brain."

_Observation._ No judicious teamster drives his animals as soon as
they have swallowed their food, but gives them a period for repose, so
that their food may be digested, and their systems invigorated. In
this way, he secures the greatest amount of labor from his team.

319. _The mind exerts an influence upon the digestive process._ This
is clearly exhibited, when an individual receives intelligence of the
loss of a friend or of property. He may at the time be sitting before
a plentiful board, with a keen appetite; but the unexpected news
destroys it, because the excited brain withholds its stimulus. This
shows the propriety of avoiding absorbing topics of thought at meals,
as labored discussions and matters of business; but substitute
cheerful and light conversation, enlivening wit, humor, the social
intercourse of family and friends; these keep the brain in action, but
not in toil. Under such circumstances, the blood and nervous fluid
flow freely, the work of digestion is readily commenced, and easily
carried on.

320. _Indigestion arising from a prostration of the nervous system,
should be treated with great care._ The food should be simple,
nutritious, moderate in quantity, and taken at regular periods. Large
quantities of stimulating food, frequently taken, serve to increase
the nervous prostration. Those afflicted should exercise in the open
air, and engage in social conversation, that the brain may be excited
to a natural or healthy action, in order that it may impart to the
digestive organs the necessary stimulation.

  -=-=-=-=-=-=-=-=-=-=-=-=

Of the Anglo-Saxon race? 318. How can the Spanish custom be improved?
319. How is the influence of the mind on the digestive process
exhibited? What does it show the necessity of avoiding? 320. How
should indigestion arising from nervous prostration be treated?

  -=-=-=-=-=-=-=-=-=-=-=-=

321. _Persons should abstain from eating, at least three hours before
retiring for sleep._ It is no unusual occurrence, for those persons
who have eaten heartily immediately before retiring to sleep, to have
unpleasant dreams, or to be aroused from their unquiet slumber by
colic pains. In such instances, the brain becomes partially dormant,
and does not impart to the digestive organs the requisite amount of
nervous influence. The nervous stimulus being deficient, the unchanged
food remains in the stomach, causing irritation of this organ.

_Illustration._ A healthy farmer, who was in the habit of eating one
fourth of a mince pie immediately before going to bed, became annoyed
with unpleasant dreams, and, among the varied images of his fancy, he
saw that of his deceased father. Becoming alarmed, he consulted a
physician, who, after a patient hearing of the case, gravely advised
him to eat _half_ of a mince pie, assuring him that he would then see
his grandfather.

322. _When the general system and digestive organs are enfeebled,
mild, unstimulating food, in small quantities, should be given._ In
the instance of a shipwrecked and famished mariner, or a patient
recovering from disease, but a small quantity of nourishment should be
given at a time. The reason for this, is, that when the stomach is
weakened from want of nourishment, it is as unfitted for a long period
of action in digesting food, as the muscles are, under like
circumstances, for walking. Consequently, knowledge and prudence
should direct the administration of food under these circumstances.
The popular adage, that "food never does harm when there is a desire
for it," is untrue, and, if practically adopted, may be injurious and
destructive to life.

  -=-=-=-=-=-=-=-=-=-=-=-=

321. What is the effect of eating immediately before retiring for
sleep? How is this illustrated in the case of a healthy farmer? 322.
How should the food be given when both the digestive organs and
general system are debilitated? Give the reason.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Liquids are rapidly removed from the stomach by
absorption. Hence, in cases of great prostration, when it is desirable
to introduce nutriment into the system, without delay, the animal and
vegetable broths are a desirable and convenient form of supplying
aliment.

323. _The condition of the skin exercises an important influence on
the digestive apparatus._ Let free perspiration be checked, either
from uncleanliness or from chills, and it will diminish the functional
action of the stomach and its associated organs. This is one of the
fruitful causes of the "liver and stomach complaints" among the
half-clothed and filthy population of the crowded cities and villages
of our country. Attention to clothing and bathing would likewise
prevent many of the diseases of the alimentary canal, called "season
complaints," particularly among children.

324. _Restricting the movements of the ribs and diaphragm impairs
digestion._ At each full inspiration, the ribs are elevated, and the
central portion of the diaphragm is depressed, from one to two inches.
This depression is accompanied by a relaxation of the anterior
abdominal walls. At each act of expiration, the relaxed abdominal
muscles contract, the ribs are depressed, the diaphragm relaxes, and
its central parts ascend. These movements of the midriff cause the
elevation and depression of the stomach, liver, and other abdominal
organs, which is a natural stimulus of these parts.

  -=-=-=-=-=-=-=-=-=-=-=-=

In cases of great prostration, what is recommended? 323. How is the
influence that the skin exercises on the digestive organs illustrated?
324. What effect on the digestive process has the restriction of the
ribs and diaphragm?

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325. It is noted of individuals who restrain the free movements of the
abdominal muscles by tight dresses, that the tone and vigor of the
digestive organs are diminished. The restricted waist will not admit
of a full and deep inspiration and so essential is this to health,
that abuse in this respect soon enfeebles and destroys the functions
of the system.

326. _Pure air is necessary to give a keen appetite and vigorous
digestion._ The digestive organs not only need the stimulus of blood,
but they absolutely need the influence of pure blood, which cannot
exist in the system, except when we breathe a pure air. From this we
learn why those persons who sleep in small, ill ventilated rooms, have
little or no appetite in the morning, and why the mouth and throat are
so dry and disagreeable. The effect of impure blood, in diminishing
the desire for food, and enfeebling the digestive organs, is well
illustrated by the following incidents.

_Illustrations._ 1st. Dr. Reid, in his work on "Ventilation of Rooms,"
relates that an innkeeper in London, when he provided a public dinner,
always spread his tables in an under-ground room, with low walls,
where the air was confined and impure. He assigned as a reason for so
doing, that his guests consumed only one third as much food and wine,
as if the tables were laid in the open air.

2d. A manufacturer stated before a committee of the British
Parliament, that he had removed an arrangement for ventilating his
mill, because he noticed that his men ate much more after his mill was
ventilated, than previous to admitting fresh air into the rooms, and
that he could not _afford_ to have them breathe pure air.

_Observation._ Many of the cases of indigestion among clergymen,
seamstresses, school teachers, sedentary mechanics, and factory
operatives, are produced by breathing the impure air of the rooms they
occupy. These cases can be prevented, as well as cured, by proper
attention to ventilation.

  -=-=-=-=-=-=-=-=-=-=-=-=

325. What is observed of those individuals that restrict the movements
of the abdominal muscles? 326. Why is pure air necessary to vigorous
digestion? Give illustration 1st. Illustration 2d. What is one cause
of indigestion among the sedentary class in community?

  -=-=-=-=-=-=-=-=-=-=-=-=

327. _The position of a person, in standing or sitting, exerts an
influence upon the digestive organs._ If a person lean, or stoop
forward, the distance between the pelvic bones and the diaphragm is
diminished. This prevents the depression of the diaphragm, while the
stomach, liver, pancreas, and other abdominal organs, suffer
compression, which induces many severe diseases of these organs. As
healthy and well-developed muscles keep the spinal column in an erect
position, which conduces to the health of the organs of digestion, the
child should be taught to avoid all positions _but the erect_, while
studying or walking. This position, combined with unrestricted waists,
will do much to remove the now prevalent disease, dyspepsia.

328. _Whatever kind of aliment is taken, it is separated into
nutriment and residuum_; the former of which is conveyed, through the
medium of the circulation, to all organs of the system, and the
latter, if not expelled, accumulates, causing headache and dizziness,
with a general uneasiness; and, if allowed to continue, it lays the
foundation of a long period of suffering and disease. For the
preservation of health, it is necessary that there should be a daily
evacuation of the residual matter.

_Observation._ In chronic diseases of the digestive organs, very
frequently, there is an inactive, or costive condition of the
alimentary canal. This may be removed in many cases, and relieved in
all instances, by friction over the abdominal organs, and by making an
effort at some stated period each day, (evening is best,) to evacuate
the residuum. In acute diseases, as fever, regard should be given to
regularity in relieving the intestines of residuum. Attention to this
suggestion will in many instances obviate the necessity of cathartic
medicine.

  -=-=-=-=-=-=-=-=-=-=-=-=

327. Why does the position of a person affect digestion? 328. Into
what are different kinds of aliment separated?

  -=-=-=-=-=-=-=-=-=-=-=-=

329. We would add, for the benefit of those afflicted with hemorrhoids,
or piles, that the best time for evacuating the intestinal canal
would be immediately before retiring for the night. During the
night, while recumbent, the protruding parts return to their proper
place, and the surrounding organs acquire increased tone to retain them.
The same observance will do much to prevent such prostrating
diseases.[12]

  [12] The urinary organs, as well as the intestinal canal, should be
       frequently and regularly evacuated. Some most distressing and
       frequently incurable complaints are caused by false customs and
       false delicacy in this particular. Teachers should be
       particularly careful, and regard this suggestion in reference
       to young pupils.

330. To recapitulate: digestion is most perfect when the action of the
cutaneous vessels is energetic; the brain and vocal organs moderately
stimulated by animated conversation; the blood well purified; the
muscular system duly exercised; the food of an appropriate quality,
taken in proper quantities, at regular periods, and also properly
masticated.

  -=-=-=-=-=-=-=-=-=-=-=-=

330. Give the summary when digestion is most perfect.

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER VXII.

THE CIRCULATORY ORGANS.


331. The ultimate object of the food and drink introduced into the
body, is to furnish material to promote the growth and repair the
waste of the organs of the system. The formation of chyle (the
nutrient portion of the food) has been traced through the digestive
process, and its transfer into the vein at the lower part of the neck,
from which it is conveyed to the heart; and, finally, in the lungs it
assimilates to the character of blood.

332. The BLOOD, after standing a short time, when drawn from its
vessels, separates into _se´rum_, (a watery fluid,) and _co-ag´u-lum_,
(clot.) This fluid is distributed to every part of the system. There
is no part so minute that it does not receive blood. The organs by
which this distribution is effected are so connected that there is
properly neither beginning nor end; but as it respects their
functions, they are connected in a complete circle. From this
circumstance, they are called the _Circulatory Organs_.


ANATOMY OF THE CIRCULATORY ORGANS.

333. The CIRCULATORY ORGANS are the _Heart_, _Ar´te-ries_, _Veins_,
and _Cap´il-la-ries_.

334. The HEART is placed obliquely, in the left cavity of the chest,
between the right and left lung. Its general form is that of an
inverted cone, the base of which is directed upward and backward,
toward the right shoulder, while its apex points forward to the left
side, about three inches from the sternum to the space between the
fifth and sixth ribs. Its under side rests upon the tendinous portion
of the diaphragm. The heart is surrounded by a sac, called the
_per-i-car´di-um_, (heart-case.) The interior surface of this membrane
secretes a watery fluid, that lubricates the exterior of the heart,
and obviates friction between it and the pericardium.

  -=-=-=-=-=-=-=-=-=-=-=-=

331. what is the ultimate object of the food? 332. Of what is the
blood composed? What is said of the distribution of the blood? 333.
Name the circulatory organs. 334-351. _Give the anatomy of the
circulatory organs._ 334. Describe the heart.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 66. A front view of the heart. 1, The right auricle
of the heart. 2, The left auricle. 3, The right ventricle. 4, The left
ventricle. 5, 6, 7, 8, 9, 10, The vessels[13] through which the blood
passes to and from the heart.]

[Illustration: Fig. 67. A back view of the heart. 1, The right auricle.
2, The left auricle. 3, The right ventricle. 4, The left ventricle. 5, 6,
7, The vessels that carry the blood to and from the heart. 9, 10, 11, The
nutrient vessels of the heart.]

  [13] All vessels that carry blood to the heart, are called _veins_.
       All vessels that carry blood _from_ the heart, are called
       _arteries_.

  -=-=-=-=-=-=-=-=-=-=-=-=

With what is it surrounded? What is its use? How much fluid does this
membrane contain when healthy?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ In health, there is usually about a tea-spoonful of
fluid in the pericardium. When these parts are diseased, it may be
thrown out more abundantly, and sometimes amounts to several ounces,
producing a disease called dropsy of the heart. But all the unpleasant
sensations in the region of the heart are not caused by an increased
amount of fluid in the pericardium, as this disease is not of frequent
occurrence.

335. The heart is composed of muscular fibres, that traverse it in
different directions, some longitudinally, but most of them in a
spiral direction. The human heart is a double organ, or it has two
sides, called the right and the left. The compartments of the two
sides are separated by a muscular _sep´tum_, or partition. Again, each
side of the heart is divided into two parts, called the _Au´ri-cle_
(deaf ear) and the _Ven´tri-cle_.

[Illustration: Fig. 68. A section of the heart, showing its cavities and
valves. 3, The right auricle. 4, The opening between the right auricle
and right ventricle. 5, The right ventricle. 6, The tricuspid valves. 7,
The pulmonary artery. 9, The semilunar valves of the pulmonary artery.
10, The septum between the right and left ventricle. 12, The left
auricle. 13, The opening between the left auricle and left ventricle. 14,
The left ventricle. 15, The mitral valves. 16, The aorta. 17, The
semilunar valves of the aorta.]

336. The AURICLES differ in muscularity from the ventricles. Their
walls are thinner, and of a bluish color. These cavities are a kind of
reservoir, designed to contain the blood arriving by the veins.

337. The VENTRICLES not only have their walls thicker than the
auricles, but they differ in their internal structure. From the
interior of these cavities arise fleshy columns, called _co-lum´næ
car´ne-æ_. The walls of the left ventricle are thicker and stronger
than those of the right.

  -=-=-=-=-=-=-=-=-=-=-=-=

335. Of what is the heart composed? Give its divisions. 336. Describe
the auricles. 337. Describe the ventricles.

  -=-=-=-=-=-=-=-=-=-=-=-=

338. The cavities in the right side of the heart are triangular in
shape; those of the left, oval. Each cavity will contain about two
ounces of blood. Between the auricle and ventricle in the right side
of the heart, there are three folds, or doublings, of thin, triangular
membrane, called the _tri-cus´pid_ valves. Between the auricle and
ventricle in the left side, there are two valves, called the
_mi´tral_. There are seen passing from the floating edge of these
valves to the columnæ carneæ, small white cords, called _chor´dæ
ten´di-næ_, which prevent the floating edge of the valve from being
carried into the auricle.

339. The right ventricle of the heart gives rise to the _Pul´mo-na-ry_
artery; the left ventricle, to a large artery called the _A-ort´a_. At
the commencement of each of these arteries there are three folds of
membrane, and from their shape, they are called _sem-i-lu´nar_
valves.

340. The heart is supplied with arteries and veins, which ramify
between its muscular fibres, through which its _nutrient_ blood
passes. It has, likewise, a few lymphatics, and many small nervous
filaments from the sympathetic system of nerves. This organ, in its
natural state, exhibits but slight indications of sensibility, and
although nearly destitute of the sensation of touch, it is yet,
however, instantly affected by every painful bodily excitement, or
strong mental emotions.

_Observation._ To obtain a clear idea of the heart and its valves, it
is recommended to examine this part of an ox or calf. In order that
each ventricle be opened without mutilating the fleshy columns,
tendinous cords, and valves, cut on each side of the septum parallel
to it. This may be easily found between the ventricles, as they differ
in thickness.

  -=-=-=-=-=-=-=-=-=-=-=-=

338. How do the cavities in the heart differ? What is found between
the auricle and ventricle in the right side of the heart? How many
valves in the left side, and their names? Where are the tendinous
cords, and what is their use? 339. What vessels proceed from the
ventricles? What is said of their valves? 340. With what is the heart
supplied? What is said of its sensibility? How can an idea of the
structure of the heart be obtained?

  -=-=-=-=-=-=-=-=-=-=-=-=

341. The ARTERIES are the cylindrical tubes that convey the blood from
the heart to every part of the system. They are dense in structure,
and preserve, for the most part, the cylindrical form, when emptied of
their blood, which is their condition after death.

342. The arteries are composed of three coats. The external, or
cellular coat, is firm and strong; the middle, or fibrous coat, is
composed of yellowish fibres. This coat is elastic, fragile, and
thicker than the external coat. Its elasticity enables the vessel to
accommodate itself to the quantity of blood it may contain. The
internal coat is a thin, serous membrane, which lines the interior of
the artery, and gives it the smooth polish which that surface
presents. It is continuous with the lining membrane of the heart.

343. Communications between arteries are free and numerous. They
increase in frequency with diminution in the size of the branches, so
that through the medium of the minute ramifications, the entire body
may be considered as one circle of inosculation. The arteries, in
their distribution through the body, are enclosed in a loose, cellular
investment, called a sheath, which separates them from the surrounding
tissues.

344. The PULMONARY ARTERY commences in front of the origin of the
aorta. It ascends obliquely to the under surface of the arch of the
aorta, where it divides into two branches, one of which passes to the
right, the other to the left lung. These divide and subdivide in the
structure of the lungs, and terminate in the capillary vessels, which
form a net-work around the air-cells, and become continuous with the
minute branches of the pulmonary veins. This artery conveys the impure
blood to the lungs, and, with its corresponding veins, establishes the
_lesser_, or _pulmonic circulation_.

  -=-=-=-=-=-=-=-=-=-=-=-=

341. What are arteries? 342. Give their structure. 343. What is said
of the communications between the arteries? In their distribution, how
are they separated from the surrounding tissues? 344. Describe the
pulmonary artery.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: The divisions of this artery continue to divide and
subdivide, until they become no larger than hairs in size. These minute
vessels pass over the air-cells, represented by small dark points around
the margin of the lungs.]

345. The AORTA proceeds from the left ventricle of the heart, and
contains the pure, or nutrient blood. This trunk gives off branches,
which divide and subdivide to their ultimate ramifications,
constituting the great arterial tree which pervades, by its minute
subdivisions, every part of the animal frame. This great artery and
its divisions, with their returning veins, constitute the _greater_,
or _systemic circulation_.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does this artery and its corresponding veins establish? Explain
fig. 69. 345. Describe the aorta. What do this artery and its
corresponding veins constitute?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 70. The aorta and its branches. 1, The commencement
of the aorta. 2, The arch of the aorta. 3, The carotid artery. 4, The
temporal artery. 5, The subclavian artery. 6, The axillary artery. 7, The
brachial artery. 8, The radial artery. 9, The ulnar artery. 10, The iliac
artery. 11, The femoral artery. 12, The tibial artery, 13. The peroneal
artery.]

346. The VEINS are the vessels which return the blood to the auricles
of the heart, after it has been circulated by the arteries through
the various tissues of the body. They are thinner and more delicate in
structure than the arteries, so that when emptied of their blood, they
become flattened and collapsed. The veins commence by minute radicles
in the capillaries, which are every where distributed through the
textures of the body, and coalesce to constitute larger and larger
branches, till they terminate in the large trunks which convey the
dark-colored blood directly to the heart. In diameter they are much
larger than the arteries, and, like those vessels, their combined area
would constitute an imaginary cone, the apex of which is placed at the
heart, and the base at the surface of the body.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does fig. 70 represent? 346. What are the veins?

  -=-=-=-=-=-=-=-=-=-=-=-=

347. The communications between the veins are more frequent than
between the arteries, and take place between the larger as well as
among the smaller vessels. The office of these inosculations is very
apparent, as tending to obviate the obstructions to which the veins
are peculiarly liable, from the thinness of their coats, and from
inability to overcome great impediments by the force of their current.
These tubes, as well as the arteries, are supplied with nutrient
vessels, and it is to be presumed that nervous filaments from the
sympathetic nerves are distributed to their coats.

348. The external, or cellular coat of the veins, is dense and firm,
resembling the cellular tunic of the arteries. The middle coat is
fibrous, like that of the arteries, but extremely thin. The internal
coat is serous, and also similar to that of the arteries. It is
continuous with the lining membrane of the heart at one extremity, and
with the lining membrane of the capillaries at the other.

349. At certain intervals, the internal coat forms folds, or
duplicatures, which constitute valves. They are generally composed of
two semilunar folds, one on each side of the vessel. The free
extremity of the valvular folds is concave, and directed forward, so
that while the current of blood sets toward the heart, they present no
impediment to its free passage; but let the current become retrograde,
and it is impeded by their distention. The valves are most numerous in
the veins of the extremities, particularly the deeper veins situated
between the muscles; but in some of the larger trunks, and also in
some of the smaller veins, no valves exist.

  -=-=-=-=-=-=-=-=-=-=-=-=

Where do they commence? 347. What is said of their communications?
What is the apparent design of the inosculations of the veins? What
vessels are distributed to the coats of the veins? 348. Give the
structure of the coats of the veins. 349. How are the valves in the
veins formed?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 71. A vein laid open to show the valves. 1, The trunk
of the vein. 2, 2, Its valves. 3, An opening of a branch into the main
trunk.]

  -=-=-=-=-=-=-=-=-=-=-=-=

What is their use? Where are they the most numerous?

  -=-=-=-=-=-=-=-=-=-=-=-=

350. The CAPILLARIES constitute a microscopic net-work, and are so
distributed through every part of the body as to render it impossible
to introduce the smallest needle beneath the skin, without wounding
several of these fine vessels. They are remarkable for the uniformity
of diameter, and for the constant divisions and communications which
take place between them.

351. The capillaries inosculate, on the one hand, with the terminal
extremity of the arteries, and on the other, with the commencement of
the veins. They establish the communication between the termination of
the arteries and the beginning of the veins. The important operations
of secretion and the conversion of the nutrient materials of the blood
into bone, muscle, &c., are performed in these vessels.

[Illustration: Fig. 72. An ideal view of a portion of the pulmonic
circulation. 1, 1, A branch of the artery that carries the impure blood
to the lungs. 3, 3, Capillary vessels. 2, 2, A vein through which red
blood is returned to the left side of the heart.]

[Illustration: Fig. 73. An ideal view of a portion of the systemic
circulation. 1, 1, A branch of the aorta. This terminates in the
capillaries, (3, 3.) 2, 2, A vein through which the impure blood is
carried to the right side of the heart.]

  -=-=-=-=-=-=-=-=-=-=-=-=

350. What do the capillaries constitute? For what are they remarkable?
351. What relation do they bear to the arteries and veins? What
important operations are performed in these vessels? What is
represented by fig. 72? By fig. 73?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XVIII.

PHYSIOLOGY OF THE CIRCULATORY ORGANS.


352. The walls of all the cavities of the heart are composed of
muscular fibres, which are endowed with the property of contracting
and relaxing, like the muscles of the extremities. The contraction and
relaxation of the muscular tissue of the heart, produce a diminution
and enlargement of both auricular and ventricular cavities. The
auricles contract and dilate simultaneously, and so do the ventricles;
yet the contraction and dilatation of the auricles do not alternate
with the contraction and dilatation of the ventricles, as the
dilatation of the one is not completed before the contraction of the
other commences. The dilatation of the ventricles is termed the
_di-as´to-le_ of the heart; their contraction, its _sys´to-le_.

353. The ventricles contract quicker and more forcibly than the
auricles, and they are three times longer in dilating than contracting.
The walls of the right ventricle, being thinner than the left, are more
distensible, and thus this cavity will contain a greater amount of
blood. This arrangement adapts it to the venous system, which is
more capacious than the arterial. The thicker and more powerful walls of
the left ventricle adapt it to expel the blood to a greater distance.

354. The valves in the heart permit the blood to flow from the
auricles to the ventricles, but prevent its reflowing. The valves at
the commencement of the aorta and pulmonary artery, permit the blood
to flow from the ventricles into these vessels, but prevent its
returning.

  -=-=-=-=-=-=-=-=-=-=-=-=

352-366. _Give the physiology of the circulatory organs._ 352. What do
the contraction and relaxation of the muscular walls of the heart
produce? How do the auricles and ventricles contract and dilate? 353.
What is said of the contraction and dilatation of the ventricles in
the heart? How is the right ventricle adapted to its function? How the
left? 354. What is the use of the valves in the heart? Those of the
aorta and pulmonary artery?

  -=-=-=-=-=-=-=-=-=-=-=-=

355. The function of the different parts of the heart will be given,
by aid of fig. 74. The blood passes from the right auricle (3) into
the right ventricle, (5,) and the tricuspid valves (6) prevent its
reflux; from the right ventricle the blood is forced into the
pulmonary artery, (7,) through which it passes to the lungs. The
semilunar valves (9) prevent this circulating fluid returning to the
ventricle. The blood, while passing over the air-cells in the lungs,
in the minute divisions of the pulmonary artery, is changed from a
bluish color to a bright red. It is then returned to the left auricle
of the heart by the pulmonary veins, (11, 11.)

[Illustration: Fig. 74. 1, The descending vena cava, (vein.) 2, The
ascending vena cava, (vein.) 3, The right auricle. 4, The opening between
the right auricle and the right ventricle. 5, The right ventricle. 6, The
tricuspid valves. 7, The pulmonary artery. 8, 8, The branches of the
pulmonary artery that pass to the right and left lung. 9, The semilunar
valves of the pulmonary artery. 10, The septum between the two ventricles
of the heart. 11, 11, The pulmonary veins. 12, The left auricle. 13, The
opening between the left auricle and ventricle. 14, The left ventricle.
15, The mitral valves. 16, 16, The aorta. 17, The semilunar valves of the
aorta.]

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355. Describe the course of the blood from the right auricle in the
heart to the lungs.

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_Observation._ If the blood is not changed in the lungs, it will not
flow to the pulmonary veins. This phenomenon is seen in instances of
death from drowning, strangling, carbonic acid, &c. The same is true,
but in a less degree, of individuals whose apparel is tight, as well
as of those who breathe impure air, or have diseased lungs.

356. The left auricle, (12,) by its contraction, forces the blood into
the left ventricle, (14.) The mitral valves (15) prevent its
reflowing. From the left ventricle the blood is forced into the aorta,
(16,) through which, and its subdivisions, it is distributed to every
part of the system. The semilunar valves (17) prevent its returning.

_Observation._ The parts of the circulatory organs most liable to
disease are the valves of the heart, particularly the mitral. When
these membranous folds become ossified or ruptured, the blood
regurgitates, and causes great distress in breathing. The operations
of the system are thus disturbed as the movements of the steam engine
would be if its valves were injured, or did not play freely.

357. The difference between the functions of the pulmonary artery and
aorta is, the former communicates with the right ventricle of the
heart, and distributes only impure blood to the lungs; the other
connects with the left ventricle of the heart, and distributes pure
blood to the whole body, the lungs not excepted. At the extremity of
the divisions of the aorta, as well as the pulmonary artery, are found
capillary vessels. This curious net-work of vessels connects with the
minute veins of the body, which return the blood to the heart.

_Observation._ The function of the veins of the systemic circulation
is similar to the office of the arteries in the lungs, and that the
veins of the pulmonic circulation transmit to the heart the pure, or
nutrient blood, and thus supply the arteries of the general system
with assimilating fluid.

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What is the effect when the blood is not changed in the lungs? 356.
Describe the circulation of the blood from the left auricle to the
general system. What part of the circulatory organs is most liable to
disease? What is the effect when the valves are diseased? 357. Give
the difference in the functions of the pulmonary artery and aorta.
Show the relation between the functions of the arteries and veins both
of the pulmonic and systemic circulation.

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358. The veins that receive the blood from all parts of the body,
follow nearly the same course as the arteries. The myriads of these
small vessels beneath the skin, and others that accompany the
arteries, at last unite and form two large trunks, called _ve´na ca´va
as-cend´ens_, and _de-scend´ens_.

_Observation._ A peculiarity is presented in the veins which come from
the stomach, spleen, pancreas, and intestines. After forming a large
trunk, they enter the liver, and ramify like the arteries, and in this
organ they again unite into a trunk, and enter the ascending vein, or
cava, near the heart. This is called the portal circulation.

359. The ventricles of the heart contract, or the "pulse" beats, about
seventy-five times every minute; in adults; in infants, more than a
hundred times every minute; in old persons, less than seventy-five
times every minute. The energy of the contraction of this organ varies
in different individuals of the same age. It is likewise modified by
the health and tone of the system. It is difficult to estimate the
muscular power of the heart; but, comparing it with other muscles, and
judging from the force with which blood is ejected from a severed
artery, it must be very great.

_Observation._ The phenomenon known under the name of pulse, is the
motion caused by the pressure of the blood against the coats of the
arteries at each contraction of the ventricles.

360. The following experiment will demonstrate that the blood flows
from the heart. Apply the fingers upon the artery at the wrist, at
two different points, about two inches apart; if the pressure be
moderately made, the "pulse" will be felt at both points. Let the
point nearest the heart be pressed firmly, and there will be no
pulsation at the lower point; but make strong pressure upon the lower
point only, and the pulsation will continue at the upper point,
proving that the blood flows from the heart, in the arteries, to
different parts of the system.

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358. What is the course of the veins? What peculiarity is observable
in the veins of the liver? 359. How often does the heart contract, or
the pulse beat, in adults? In infants? In old persons? What is said of
the energy of its contraction in different persons? How is the pulse
produced? 360. Demonstrate by experiment that the blood flows from the
heart.

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361. There are several influences, either separately or combined that
propel the blood from the heart through the arteries, among which may
be named,--1st. The contraction of the muscular walls of the heart.
2d. The contractile and elastic middle coat of the arteries aids the
heart in impelling the blood to the minute vessels of the system. 3d.
The peculiar action of the minute capillary vessels is considered, by
some physiologists, as a motive power in the arterial circulation.
4th. The pressure of the muscles upon the arteries, when in a state of
contraction, is a powerful agent, particularly when they are in active
exercise.

362. The following experiments will demonstrate that the blood from
every part of the system flows to the heart by the agency of the
veins. 1st. Press firmly on one of the veins upon the back of the
hand, carrying the pressure toward the fingers; for a moment, the vein
will disappear. On removing the pressure of the finger, it will
reappear, from the blood rushing in from below.

2d. If a tape be tied around the arm above the elbow, the veins below
will become larger and more prominent, and also a greater number will
be brought in view, while the veins above the tape are less distended.
At this time, apply the finger at the wrist, and the pulsation of the
arteries still continues, showing that the blood is constantly flowing
from the heart through the arteries, into the veins; and the
increased size of the veins shows that the pressure of the tape
prevents its flowing back to the heart.

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361. State the influences that propel the blood from the heart. 362.
Demonstrate by the first experiment that the blood flows to the heart.
By the second experiment.

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363. The influences that return the blood to the heart through the
veins, are not so easily understood as those that act on the blood in
the arteries. Some physiologists have imputed an active propulsive
power to the capillary vessels in carrying the blood through the
veins. This is not easily explained, and perhaps it is as difficult to
understand. An influence upon which others have dwelt, is the suction
power of the heart in active dilatation, acting as a _vis a fronte_
(power in front) in drawing blood to it.

364. Another influence that aids the venous circulation is attributed
to the propulsive power of the heart. It is not easy to comprehend how
this power of the heart can be extended through the capillary vessels
to the blood in the veins. Again, an important agency has been found,
by some physiologists, in the inspiratory movements, which are
supposed to draw the blood of the veins into the chest, in order to
supply the vacuum which is created there by the elevation of the ribs
and the descent of the diaphragm.

365. One of the most powerful causes which influence the venous
circulation, is the frequently-recurring action of the muscles upon
the venous trunks. When the muscles are contracted, they compress that
portion of the veins which lie beneath the swell, and thus force the
blood from one valve to the other, toward the heart. When they are
relaxed, the veins refill, and are compressed by the recurring action
of the muscles.

_Observation._ The physician, in opening a vein, relies on the
energetic contractions and sudden relaxations of the muscles, when he
directs the patient to clasp the head of a cane, or the arm of a
chair; these alternate motions of the muscles cause an increased flow
of blood to the veins of the ligated arm.

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363. What is said of the influences that return the blood to the
heart? What is said of the propulsive power of the capillaries? Of the
suction power of the heart? 364. Give another influence. State another
agency. 365. What is one of the most powerful causes which influence
venous circulation? Give practical observation.

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[Illustration: Fig. 75. An ideal view of the circulation in the lungs and
system. From the right ventricle of the heart, (2,) the dark, impure
blood is forced into the pulmonary artery, (3,) and its branches (4, 5)
carry the blood to the left and right lung. In the capillary vessels (6,
6) of the lungs, the blood becomes pure, or of a red color, and is
returned to the left auricle of the heart, (9,) by the veins, (7, 8.)
From the left auricle the pure blood passes into the left ventricle,
(10.) By a forcible contraction of the left ventricle of the heart, the
blood is thrown into the aorta, (11.) Its branches (12, 13, 13) carry the
pure blood to every organ or part of the body. The divisions and
subdivisions of the aorta terminate in capillary vessels, represented by
14, 14. In these hair-like vessels the blood becomes dark colored, and is
returned to the right auricle of the heart (1) by the vena cava
descendens, (15,) and vena cava ascendens, (16.) The tricuspid valves
(17) prevent the reflow of the blood from the right ventricle to the
right auricle. The semilunar valves (18) prevent the blood passing from
the pulmonary artery to the right ventricle. The mitral valves (19)
prevent the reflow of blood from the left ventricle to the left auricle.
The semilunar valves (20) prevent the reflow of blood from the aorta to
the left ventricle.]

366. The muscles exercise an agency in maintaining the venous
circulation at a point above what the heart could perform. As the
pulsations are diminished by rest, so they are accelerated by
exercise, and very much quickened by violent effort. There can be
little doubt that the increased rapidity of the return of blood
through the veins, is, of itself, a sufficient cause for the
accelerated movements of the heart during active exercise.

_Observation._ The quantity of blood in different individuals varies.
From twenty-five to thirty-five pounds may be considered an average
estimate in a healthy adult of medium size. The time in which the
blood courses through the body and returns to the heart, is different
in different individuals. Many writers on physiology unconditionally
limit the period to three minutes. It is undeniable that the size and
health of a person, the condition of the heart, lungs, and brain, the
quantity of the circulating fluid, the amount and character of the
inspired air, and the amount of muscular action, exert a modifying
influence. The time probably varies from three to eight minutes.

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366. What causes the accelerated movements of the heart during active
exercise?

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_Note._ Let the pupil review the anatomy and physiology of the
circulatory organs from fig. 75, or from anatomical outline plates,
No. 6 and 7.



CHAPTER XIX.

HYGIENE OF THE CIRCULATORY ORGANS


367. If any part of the system is deprived of blood, its vitality will
cease; but, if the blood is lessened in quantity to a limited extent,
only the vigor and health of the part will be impaired. The following
conditions, if observed, will favor the free and regular supply of
blood to all portions of the system.

368. _The clothing should be loosely worn._ Compression of any kind
impedes the passage of blood through the vessels of the compressed
portion. Hence, no article of apparel should be worn so as to prevent
a free flow of blood through every organ of the body.

369. The blood which passes to and from the brain, flows through the
vessels of the neck. If the dressing of this part of the body is
close, the circulation will be impeded, and the functions of the brain
will be impaired. This remark is particularly important to scholars,
public speakers, and individuals predisposed to apoplexy, and other
diseases of the brain.

370. As many of the large veins lie immediately beneath the skin,
through which the blood is returned from the lower extremities, if the
ligatures used to retain the hose, or any other article of apparel, in
proper position, be tight and inelastic, the passage of blood through
these vessels will be obstructed, producing, by their distention, the
varicose, or enlarged veins. Hence elastic bands should always be used
for these purposes.

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367-386. _Give the hygiene of the circulatory organs._ 367. What
effect will be produced on the body if it is deprived of blood? If the
blood is only lessened in quantity? 368. Why should the clothing be
worn loose? 369. What is said of dressing the neck? To what persons is
this remark applicable? 370. How are enlarged veins frequently
produced?

  -=-=-=-=-=-=-=-=-=-=-=-=

371. _An equal temperature of all parts of the system promotes
health._ A chill on one portion of the body diminishes the size of
its circulating vessels, and the blood which should distend and
stimulate the chilled part, will accumulate in other organs. The
deficiency of blood in the chilled portion induces weakness, while the
superabundance of sanguineous fluid may cause disease in another
part of the system.

372. _The skin should be kept not only of an equal, but at its natural
temperature._ If the skin is not kept warm by adequate clothing, so
that chills shall not produce a contraction of the blood-vessels and a
consequent paleness, the blood will recede from the surface of the
body, and accumulate in the internal organs. Cleanliness of the skin
is likewise necessary, for the reason, that this condition favors the
free action of the cutaneous vessels.

_Observation._ When intending to ride in a cold day, wash the face,
hands, and feet, in cold water, and rub them smartly with a coarse
towel. This is far better to keep the extremities warm, than to take
spirits into the stomach.

373. _Exercise promotes the circulation of the blood._ As the action
of the muscles is one of the important agents which propel the blood
through the arteries and veins, daily and regular exercise of the
muscular system is required to sustain a vigorous circulation in the
extremities and skin, and also to maintain a healthy condition of the
system. The best stimulants to improve the sluggish circulation of an
indolent patient, whose skin is pale and whose extremities are cold,
are the union of vigorous muscular exercise with agreeable mental
action, and the systematic application to the skin of cold water,
attended with friction.

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371. Why should the temperature of the body be equal? 372. Why should
the skin be kept at its natural, as well as at an equal temperature?
What practical observation when intending to ride in a cold day? 373.
Why does exercise promote health? What are good stimulants for
sluggish circulation in the indolent?

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_Illustration._ The coach-driver and teamster throw their arms around
their bodies to warm them when cold. The muscles that are called into
action in swinging the arms, force a greater quantity of blood into
the chilled parts, and consequently, more heat is produced.

374. When a number of muscles are called into energetic action, a
greater quantity of blood will be propelled to the lungs and heart in
a given time, than when the muscles are in a state of comparative
inaction. It is no uncommon occurrence, that before there is a proper
expansion of the respiratory organs to correspond with the frequency
and energy of the movements of the muscles, there is an accumulation
of blood in the lungs, attended by a painful sensation of fulness and
oppression in the chest, with violent and irregular action of the
heart. This condition of the organs of the chest, called _congestion_,
may be followed by cough, inflammation of the lungs, asthma, and a
structural disease of the heart.

375. To avoid these sensations and results, when we feel necessitated
to walk or run a considerable distance in a short time, commence the
movements in a moderate manner increasing the speed as the respiratory
movements become more frequent and their expansion more extensive, so
that a sufficient amount of air may be received into the lungs to
purify the increased quantity of blood forced into them. The same
principles should be observed when commencing labor, and in driving
horses and other animals.

_Observation._ When a large number of muscles are called into action
after repose, as when we rise from a recumbent or sitting posture,
the blood is impelled to the heart with a very strong impetus. If that
organ should be diseased, it may arrive there in larger quantities
than can be disposed of, and death may be the result. Hence the
necessity of avoiding all sudden and violent movements, on the part of
those who have either a functional or structural disease of the
heart.

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Mention the illustration. 374. What is the effect when a number of
muscles are called into energetic action? What effect has this
accumulation of blood in the lungs? 375. How can such disagreeable
sensations be avoided? Mention a practical observation.

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376. _The mind exercises no inconsiderable influence upon the
circulatory organs._ When an individual is stimulated by hope, or
excited by anger, the heart beats more forcibly, and the arteries act
more energetically, than when a person is influenced by fear, despair,
or sorrow. Consequently, the system is more fully nourished, and
capable of greater exertion, when the former condition obtains, than
when the latter exists.

377. _The quality and quantity of the blood modify the action of the
heart and blood-vessels._ If this fluid is abundant and pure, the
circulatory vessels act with more energy than when it is deficient in
quantity or defective in quality.

_Illustrations._ 1st. In an athletic man, whose heart beats forcibly,
and whose pulse is strong, if a considerable quantity of blood is
drawn from a vein, as in bleeding, the heart will beat feebly, and the
pulse will become weak.

2d. When the blood is made impure by inhaling vitiated air, the action
of the heart and arteries is diminished, which produces an effect
similar to that which takes place when blood is drawn from a vein.

378. _Hemorrhage from divided arteries should be immediately
arrested._ When large blood-vessels are wounded or cut, the flow of
blood must be immediately stopped, or the person soon faints, and the
heart ceases its action. If it is a large artery that is wounded, the
blood will be thrown out in jets, or jerks, every time the pulse
beats. The flow of blood can be stopped until a surgeon arrives,
either by compressing the vessel between the wound and the heart, or
by compressing the end of the divided artery in the wound.

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376. State some of the effects that the mind has on circulation. 377.
What effect have the quantity and quality of blood upon the
circulatory organs? Give illustration 1st. Illustration 2d. 378. What
is necessary when large blood-vessels are wounded or cut?

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[Illustration: Fig. 76. The track of the large artery of the arm. 1, The
collar-bone. 9, The axillary artery. 10, The brachial artery.]

[Illustration: Fig. 77. B, The manner of compressing the artery near the
collar-bone. A, The manner of compressing the large artery of the arm,
with the fingers. C, The manner of compressing the divided extremity of
an artery in the wound, with a finger.]

379. After making compression with the fingers, as described and
illustrated, take a piece of cloth or handkerchief, twist it
cornerwise, and tie a hard knot midway between the two ends. This
knot should be placed over the artery, between the wound and the
heart, and the ends carried around the limb and loosely tied. A stick,
five or six inches long, should be placed under the handkerchief,
which should be twisted until the knot has made sufficient compression
on the artery to allow the removal of the fingers without a return of
bleeding. Continue the compression until a surgeon can be called.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is shown by fig. 76? By fig. 77? 379. What is to be done after
compressing the wound, as before described?

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[Illustration: Fig. 78. A, B, The track of the large artery of the arm.
The figure exhibits the method of applying the knotted handkerchief to
make compression on this artery.]

[Illustration: Fig. 79. A, C, The track of the large artery of the thigh.
B, The method of applying the knotted handkerchief to compress this
artery. In practice, the twisting stick B should be placed opposite the
knot over the artery A, C.]

380. When an artery of the arm is cut, elevating the wounded limb
above the head will tend to arrest the flow of blood. In a wound of a
lower limb, raise the foot, so that it shall be higher than the hip,
until the bleeding ceases.

_Illustration._ On one occasion, the distinguished Dr. Nathan Smith
was called to a person who had divided one of the large arteries
below the knee. After trying in vain to find the bleeding vessel, so
as to secure it, he caused the foot to be elevated higher than the
hip. At the first instant the blood was forced from the wound about
twelve inches; in a minute, it was diminished to three or four; and,
in a short time, the bleeding ceased. This Dr. S. called his "_great_"
operation; and it was truly great in _simplicity_ and _science_.

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What is shown by fig. 78 and 79? 380. What suggestion relative to the
position of a limb when bleeding? Relate a simple operation by Dr.
Nathan Smith.

  -=-=-=-=-=-=-=-=-=-=-=-=

381. The practical utility of every person knowing the proper means of
arresting hemorrhage from severed arteries, is illustrated by the
following incidents. In 1848, in the town of N., Mass., a mechanic
divided the femoral artery; although several adult persons were
present, he died in a few minutes from loss of blood, because those
persons were ignorant of the method of compressing severed arteries
until a surgeon could be obtained.

382. In 1846, a similar accident occurred in the suburbs of
Philadelphia. While the blood was flowing copiously, a lad, who had
received instruction on the treatment of such accidents at the
Philadelphia High School, rushed through the crowd that surrounded the
apparently dying man, placed his finger upon the divided vessel, and
continued the compression until the bleeding artery was secured by a
surgeon.

383. In "flesh wounds," when no large blood-vessel is divided, wash
the part with cold water, and, when bleeding has ceased, draw the
incision together, and retain it with narrow strips of adhesive
plaster. These should be put on smoothly, and a sufficient number
applied to cover the wound. In most instances of domestic practice,
the strips of adhesive plaster are too wide. They should not exceed in
width one fourth of an inch. Then apply a loose bandage, and avoid
all "healing salves," ointments, and washes. In removing the dressing
from a wound, both ends of the strips of plaster should be raised and
drawn toward the incision. The liability of the wound re-opening is
thus diminished.

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381. Relate the first incident showing the utility of every person
knowing the proper method of arresting the flow of blood from divided
arteries. 382. The second incident. 383. How should "flesh wounds" be
dressed?

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_Observation._ The union of the divided parts is effected by the
action of the divided blood-vessels, and not by salves and ointments.
The only object of the dressing is to keep the parts together, and
protect the wound from air and impurities. _Nature_, in all cases of
injuries, performs her own cure. Such simple wounds do not generally
require a second dressing and should not be opened until the incisions
are healed.

[Illustration: Fig. 80. The manner in which strips of adhesive plaster
are applied to wounds.]

384. In wounds made by pointed instruments, as a nail, or in lacerated
wounds, as those made by forcing a blunt instrument, as a hook, into
the soft parts, there will be no direct and immediate union. In these
cases, apply a soothing poultice, as one made of linseed meal, and
also keep the limb still. It is judicious to consult a physician
immediately, in punctured or lacerated wounds, because they often
induce the most dangerous diseases.

385. Wounds caused by the bite of rabid animals or venomous serpents,
should be immediately cleansed with pure water. In many instances,
the application of suction, either with "cupping glasses," or the
mouth, will prevent the introduction of the poisonous matter into the
system by absorption. When this is effected, cover the wound with a
soothing poultice, as one made of slippery elm bark.

  -=-=-=-=-=-=-=-=-=-=-=-=

What should be avoided? How should the strips of plaster be removed
from a wound? How is the union of the divided parts effected? 384. How
should punctured and lacerated wounds be dressed? 385. What is the
treatment of wounds caused by the bite of rabid animals?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Although animal poisons, when introduced into the
circulating fluid through the broken surface of the skin, frequently
cause death, yet they can be taken into the mouth and stomach with
impunity, if the mucous membrane which lines these parts is not
broken.

[Illustration: Fig. 81. _a_, _a_, Representation of wounds on the back
part of the arm and fore-arm _b_, _b_, Wounds on the anterior part of the
arm and fore-arm. By bending the elbow and wrist, the incisions at _a_,
_a_, are opened, while those at _b_, _b_, are closed. Were the arm
extended at the elbow and wrist, the wounds at _a_, _a_, would be closed,
and those at _b_, _b_, would be opened.]

386. The proper position of the limbs favors the union of wounds. If
the incision be upon the anterior part of the leg, between the knee
and ankle, extending the knee and bending the ankle will aid its
closing. If it be upon the back part of the leg, by extending the foot
and bending the knee, the gaping of the incision will be diminished.
When wounds occur upon the trunk or upper extremities, let the
position of the person be regarded.

  -=-=-=-=-=-=-=-=-=-=-=-=

386 Does the proper position of the limbs favor the union of wounds?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XX.

ABSORPTION.


387. ABSORPTION is the process by which the materials of nutrition are
removed from the alimentary canal, to be conveyed into the circulatory
vessels. It is likewise the process by which the particles of matter
that have become injurious, or useless, are removed from the mass of
fluids and solids of which the body is composed. These renovating and
removing processes are performed by two sets of vessels


ANATOMY OF THE LYMPHATIC VESSELS.

388. The vessels that act exclusively for the growth and renovation of
the system, are found only in the alimentary canal. They are called
lacteals. The vessels whose sole function is to remove particles of
matter already deposited, are called _Lym-phat´ics_. The radicles, or
commencement of the veins, in many, and it may be in all parts of the
body, perform the office of absorption.

_Observation._ This fact accounts for the capacity of the venous
system exceeding the arterial. Had the veins no other function to
perform, beside returning the blood that had been distributed by the
arteries, it would be reasonable to suppose that this system would be
less than the arterial, but the reverse is known to be true.

389. The LYMPHATIC VESSELS, in structure, resemble the lacteals. They
exist in great numbers in the skin and mucous membranes, particularly
those of the lungs. Though no lymphatics have been traced to the
brain, it is presumed that they exist there, as this part of the body
is not exempt from the composition and decomposition, which are
perpetual in the body. These vessels are extremely minute at their
origin, so that in many parts of the system they cannot be detected
without the aid of a microscope.

  -=-=-=-=-=-=-=-=-=-=-=-=

387. Define absorption. 388-391. _Give the anatomy of the lymphatic
vessels._ 388. What are those vessels called that act exclusively for
the growth and renovation of the body? Those whose office is to remove
the atoms already deposited? What other vessels perform the office of
absorption? Give observation. 389. Describe the lymphatics.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 82. A single lymphatic vessel, much magnified.]

[Illustration: Fig. 83. The valves of a lymphatic trunk.]

[Illustration: Fig. 84. 1, A lymphatic gland with several vessels passing
through it.]

390. The lymphatic vessels, like the veins, diminish in number as they
increase in size, while pursuing their course toward the large veins
near the heart, into which they pour their contents. The walls of
these vessels have two coats of which the external one is cellular,
and is capable of considerable distention. The internal coat is folded
so as to form valves, like those in the veins. Their walls are so
thin, that these folds give them the appearance of being knotted.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is represented by fig. 82? By fig. 83? By fig. 84? 390. In what
respect do these vessels resemble the veins of the system? Give the
structure of their coats.

  -=-=-=-=-=-=-=-=-=-=-=-=

391. At certain points, the lymphatic vessels pass through distinct,
soft bodies, peculiar to themselves, which are called _lymphatic
glands_, which are to these vessels what the mesenteric glands are to
the lacteals. The lymphatic glands vary in form and in size. They are
extremely vascular, and appear to consist of a collection of minute
vessels. These glands are found in different parts of the body, but
are most numerous in the groins, axilla, or arm-pits, neck, and
cavities of the chest and abdomen.

_Observation._ From exposure to cold, these glands are frequently
enlarged and inflamed. They are known under the name of "kernels."
They are often diseased, particularly in scrofula, or "king's evil."


PHYSIOLOGY OF THE LYMPHATIC VESSELS.

392. Though the lacteals and lymphatics resemble each other in their
structure and termination, yet they differ as to the nature of the
fluids which they convey, as well as the nature of their functions.
The lacteals open into the small intestine, and possess the power of
rejecting all substances in the passing aliment, but the chyle. The
lymphatics, on the contrary, not only imbibe all the various
constituents of the body, both fluid and solid, but they sometimes
absorb foreign and extraneous substances, when presented to their
mouths, as in vaccination.

393. The varieties of absorption are, the _In-ter-sti´tial_,
_Rec-re-men-ti´tial_, _Ex-cre-men-ti´tial_, _Cu-ta´ne-ous_,
_Res-pi´ra-to-ry_, _Ve´nous_, and the _Lac´te-al_.

  -=-=-=-=-=-=-=-=-=-=-=-=

391. Describe the lymphatic glands. What observation is given in
regard to these glands? 392-403. _Give the physiology of the lymphatic
vessels._ 392. Explain the difference between the lacteals and
lymphatics 393. Name the varieties of absorption.

  -=-=-=-=-=-=-=-=-=-=-=-=

394. INTERSTITIAL absorption is that change which is constantly going
on in the animal economy among the particles of matter of which every
texture is composed. The ordinary functions of the body, in health,
require incessant action of the lymphatics; the circulatory system,
with its myriads of small vessels, is constantly depositing new atoms
of matter, which become vitalized, and perform a course of actions,
then die, or become useless. These old atoms are removed by the
absorbent system. Thus, wherever there is a minute artery to deposit a
living particle of matter, there is a lymphatic vessel, or venous
radicle, to remove it as soon as it shall have finished its particular
office.

395. The action of the lymphatic vessels counterbalances those of
nutrition, and thus the form and size of every part of the body is
preserved. When their action exceeds that of the nutrient vessels, the
body emaciates; when it is deficient, plethora is the result. In
youth, they are less active than the nutrient vessels, and the limbs
are plump; but in later periods of life, we find these actions
reversed, and the body diminishes in size. It is not unfrequent that
wens, and other tumors of considerable size, disappear, and even the
entire bone of a limb has been removed from the same general cause.
The effused fluids of bruises are also removed by absorption.

_Observations._ 1st. When little or no food is taken into the stomach,
life is supported by the lymphatic vessels and veins imbibing the fat
and reconveying it into the blood vessels. It is the removal of this
secretion which causes the emaciation of the face and extremities of a
person recovering from a fever. In consumption, the extreme
attenuation of the limbs is caused by the absorption, not only of the
fat, but also of the muscles and more solid parts of the system.

  -=-=-=-=-=-=-=-=-=-=-=-=

394. What is interstitial absorption? Flow are the new atoms of matter
deposited? How removed? 395. What vessels do the lymphatics
counterbalance in action? What is the result when their action exceeds
that of the nutrient vessels? When it is less? Mention some instances
of active absorption. What causes the emaciated limbs of a person
recovering from fever? The extreme attenuation in consumption?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. Animals which live in a half torpid state during the winter,
derive their nourishment from the same source. In other words, we may
say the starving animal lives for a time upon itself, eating up, by
internal absorption, such parts of the body as can be spared under
urgent necessity, to feed those organs and continue those functions
that are absolutely essential to life.

396. RECREMENTITIAL absorption is the removal of those fluids from the
system, which are secreted upon surfaces that have no external outlet.
These fluids are various, as the fat, the marrow, the synovia of
joints, serous fluids, and the humors of the eye. Were it not for this
variety of absorption, dropsy would generally exist in the cavities of
the brain, chest, and abdomen, from the continued action of the
secretory vessels.

397. EXCREMENTITIAL absorption relates to the fluids which have been
excreted, such as the bile, pancreatic fluid, saliva, milk, and other
secretions.

398. CUTANEOUS absorption relates to the skin. Here the lymphatic
vessels extend only to the cuticle, which they do not permeate. There
has been much diversity of opinion on the question of cutaneous
absorption; some maintaining that this membrane absorbs, while others
deny it. Many experiments have proved that the skin may absorb
sufficient nutriment to support life for a time, by immersing the
patient in a bath of milk or broth. It has been found that the hand,
immersed to the wrist in warm water, will absorb from ninety to one
hundred grains of fluid in the space of an hour.

399. Thirst may be quenched by applying moist clothes to the skin, or
by bathing. It is no uncommon occurrence, during a passage from one
continent to the other, for the saliva to become bitter by the
absorption of sea water. Medicinal substances, such as mercury,
morphine, and Spanish flies, are frequently introduced into the system
through the skin.

  -=-=-=-=-=-=-=-=-=-=-=-=

396. What is recrementitial absorption? 397. Define excrementitial
absorption. 393. To what does cutaneous absorption relate? Is there a
diversity of opinion respecting this variety of absorption? What do
well attested experiments show? 399. What remark in reference to
quenching thirst? What agency conveys medicinal substances and
ointments into the system when tabbed on the skin?

  -=-=-=-=-=-=-=-=-=-=-=-=

400. RESPIRATORY absorption has reference to the lungs. The mucous
membrane of these organs is abundantly supplied with lymphatic
vessels. By their action, substances finely pulverized, or in the form
of gas, are readily imbibed when inhaled into the lungs, such as
metallic vapors, odoriferous particles, _tobacco smoke_, and other
effluvia. In this way, contagious diseases are frequently contracted.

_Illustration._ In inhaling sulphuric ether, or letheon, it is
introduced into the vessels of the lungs in the form of vapor, and
through them it is rapidly conveyed to the brain, and thus influences
the nervous system.

401. VENOUS absorption is the function which the veins perform in
absorbing from the alimentary canal liquids of various kinds that have
been taken into the stomach and are not converted into chyle. In other
parts of the body, they also perform the common office of lymphatics.

402. LACTEAL, or digestive absorption has reference to the absorption
of chyle only, which is destined for the nutrition of the body.

403. Absorption is not only very abundant, but generally very rapid,
and all these varieties are maintained through life, except when
suspended by disease.

  -=-=-=-=-=-=-=-=-=-=-=-=

400. What is said of respiratory absorption? How is letheon introduced
into the system? 401. Define venous absorption. 402. What is lacteal
absorption? 403. What is said of absorption?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 85. A representation of the lymphatic vessels and
glands. 1, 2, 3, 4, 5, 6, The lymphatic vessels and glands of the lower
limbs. 7, Lymphatic glands. 8, The commencement of the thoracic duct. 9,
The lymphatics of the kidney. 10, Of the stomach. 11, Of the liver. 12,
12, Of the lungs. 13, 14, 15, The lymphatics and glands of the arm. 16,
17, 18, Of the face and neck. 19, 20, Large veins. 21, The thoracic duct.
26, The lymphatics of the heart.]


HYGIENE OF THE LYMPHATIC VESSELS.

404. By the action of the lymphatics, substances of an injurious, as
well as of a beneficial, character may be conveyed into the system.
These vessels, under certain conditions, are more active in their
office than at other periods; and it is of practical utility to know
what influences their action.

405. _The function of these vessels is increased by moisture, and
lessened by an active state of the lacteals._ Observation shows that
the ill-fed, and those persons that live in marshy districts, contract
contagious diseases more readily than those individuals who are well
fed, and breathe a dry and pure air.

406. _The air of the sick-room should be dry._ If due attention is not
given to ventilation, the clothing of the nurse and patient, together
with the air of the room, will be moistened by the exhalations from
the skin and lungs. This exhalation may contain a poison of greater or
less power, according to its quantity and degree of concentration, and
may be absorbed and reconveyed into the system, causing inflammatory
diseases, and not unfrequently death.

_Observations._ 1st. When we are attending a sick person a current of
air that has passed over the patient should be avoided. We may
approach with safety very near a person who has an infectious disease,
provided care is taken to keep on the side from which the currents of
air are admitted into the room.

2d. When we have been visiting or attending on a sick person, it is
judicious to change the apparel worn in the sick-room, and also give
the skin a thorough bathing. The outside garments, also, should be
aired, as poisonous matter may have penetrated the meshes of the
clothing.

  -=-=-=-=-=-=-=-=-=-=-=-=

404-413. _Give the hygiene of the lymphatic vessels._ 404. What is
said respecting the action of the lymphatic vessels? 405. What
influences the function of these vessels? What does observation show?
406. Why should the air of the sick-room be dry? What suggestion when
we have been visiting or attending on the sick?

  -=-=-=-=-=-=-=-=-=-=-=-=

407. _The stomach should be supplied with food of a nutrient and
digestible character, in proper quantities, and at stated periods._
The chyle formed from the food stimulates the lacteals to activity,
which activity is attended with an inactive state of the lymphatics of
the skin and lungs. Thus due attention should be given to the food of
the attendants on the sick, and the members of the family. Before
visiting a sick person it is judicious to take a moderate amount of
nutritious food.

_Observation._ Many individuals, to prevent contracting disease that
may be communicated from one person to another, use tobacco, either
chewed or smoked; and sometimes alcohol, with decoctions of bitter
herbs. These substances do not diminish, but tend to increase, the
activity of the lymphatics. Thus they make use of the means by which
the poisonous matter formed in the system of the diseased person, may
be more readily conveyed into their own.

408. _The skin and clothing, as well as the bed-linen, should be
frequently cleansed._ This will remove the poisonous matter that may
be deposited upon the skin and garments, which, if suffered to remain,
might be conveyed into the system by the action of the lymphatics.
This points also to a frequent change of the wearing apparel, as well
as the coverings of the bed. In visiting the unhealthy districts of
the South and West, the liability of contracting disease is much
lessened by taking a supply of food at proper periods, keeping the
skin and clothing in a clean state, the room well ventilated, and
avoiding the damp chills of evening.

409. _Absorption by the skin is most vigorous when the cuticle is
removed by vesication, or blistering._ Then external applications are
brought into immediate contact with the orifices of the lymphatics of
the skin, and by them rapidly imbibed and circulated through the
system. Thus arsenic applied to the cutaneous vessels, and strong
solutions of opium to extensive burns, have been absorbed in
quantities sufficient to poison the patient.

  -=-=-=-=-=-=-=-=-=-=-=-=

407. Why should the stomach be supplied with food of a nutrient and
digestible character? What is said of the use of alcohol, or tobacco,
in preventing the introduction of the poisonous matter of contagious
diseases? 408. Why should the clothing and bed-linen be frequently
washed? What suggestion to persons in visiting the unhealthy districts
of the South and West? 409. When is cutaneous absorption most
vigorous? Why?

  -=-=-=-=-=-=-=-=-=-=-=-=

410. _When the cuticle is only punctured or abraded, poisonous matter
may be introduced into the system._ The highly respected Dr. W., of
Boston, lost his life by poisonous matter from the body of a patient
subjected to a post mortem examination. He had removed from his
finger, previous to the examination, a "hang-nail," and the poison
from the dead body was brought in contact with the denuded part, and
through the agency of the lymphatics it was conveyed into the system.

411. Puncture any part of the cuticle with the finest instrument that
has upon its point the smallest conceivable quantity of the _vaccine
virus_, or small-pox matter, and it will be brought into contact with
the lymphatic vessels, and through their agency conveyed into the
system. The result is, that persons thus operated upon have the
small-pox, or the vaccine disease.

412. When we expose ourselves to any poisonous vapors, or handle
diseased animals or sick persons, safety and health require that the
cuticle be not broken or otherwise injured. In many instances, the
poisonous animal matter upon hides has been introduced into the
systems of tanners, through small ulcers upon their fingers or hands.
From these sores there would be seen small red lines extending up the
arm. These swelled tracts indicate an inflammation of the large
lymphatic trunks, that have been irritated and diseased by the
passage of poisonous matter through them into the system.

  -=-=-=-=-=-=-=-=-=-=-=-=

410. Do the same results follow, if the cuticle is only punctured?
Relate an instance of death by the absorption of poisonous matter.
411. By what means is the vaccine matter introduced into the system?
412. What caution is necessary when we expose ourselves to poisonous
vapors?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ A distressing illustration of the absorption of
deleterious substances from the surface of a sore, is seen in the
favorite experiments of that class of "quacks," who style themselves
"cancer doctors." With them, every trifling and temporary enlargement,
or tumor, is a cancer. Their general remedy is arsenic; and happy is
the unfortunate sufferer who escapes destruction in their hands, for
too frequently their speedy cure is death.

413. In case of an accidental wound, it is best immediately to bathe
the part thoroughly in pure water, and to avoid all irritating
applications. In some instances, it would be well to apply _lunar
caustic_ immediately. When handling or shrouding dead bodies, or
removing the skin from animals that have died of disease, it would
be well to lubricate the hands with olive-oil or lard. This affords
protection to the minute portions of the skin, from which the cuticle
may be removed. In all cases where there is an ulcer or sore, the
part should be covered with something impervious to fluids, as
court-plaster, before exposing the system to any animal, vegetable,
or mineral poison.

  -=-=-=-=-=-=-=-=-=-=-=-=

413. What direction is given when the cuticle is broken? What
suggestion is given when shrouding dead bodies?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXI.

SECRETION.


414. In the human body are found many fluids and solids of dissimilar
appearance and character. These are produced by the action of organs,
some of which are of simple structure, while others are very complicated
in their arrangement. These organs are called _Se-cre´to-ry_.


ANATOMY OF THE SECRETORY ORGANS.

415. The SECRETORY ORGANS are the _Ex-ha´lants_, _Fol´li-cles_, and
the _Glands_.

416. The EXHALANTS were supposed to be terminations of arteries or
capillaries. The external exhalants terminate on the skin and mucous
membranes; the internal in the cellular and medullary tissues.
(Appendix I.)

[Illustration: Fig. 86. A secretory follicle. An artery is seen, which
supplies the material for its secretion. Follicles are also supplied with
veins and organic nerves.]

417. The FOLLICLES are small bags, or sacs, situated in the true skin,
and mucous membrane. The pores seen on the skin are the outlets of
these bodies.

  -=-=-=-=-=-=-=-=-=-=-=-=

414. How are the fluids and solids of the body produced? 415-419.
_Give the anatomy of the secretory organs._ 415. Name the secretory
organs. 416. Describe the exhalants. What is represented by fig. 86?
417. Define follicles.

  -=-=-=-=-=-=-=-=-=-=-=-=

418. The GLANDS are soft, fleshy organs, and as various in their
structure, as the secretions which it is their function to produce.
Each gland is composed of many small lobules united in a compact mass,
and each lobule communicates by a small duct with the principal
outlet, or duct of the organ. Every gland is supplied with arteries,
veins, lymphatics, and nerves. These, with the ducts, are arranged in
a peculiar manner, and connected by cellular membrane.

419. There are two classes of glands, one for the modification of the
fluids which pass through them, as the mesenteric and lymphatic
glands; and the other for the secretion of fluids which are either
useful in the animal economy, or require to be rejected from the
body.

[Illustration: Fig. 87. 1, 1, A secretory gland. 2, 2, Minute ducts that
are spread through the glands. These coalesce to form the main duct, 3.]


PHYSIOLOGY OF THE SECRETORY ORGANS.

420. SECRETION is one of the most obscure and mysterious functions of
the animal economy. "It is that process by which various substances
are separated from the blood, either with or without experiencing any
change during their separation." Not only is the process by which
substances are separated from the blood, called secretion, but the
same term is also applied to substances thus separated. Thus
physiologists say, that by the process of secretion, bile is formed by
the liver; and also, that bile is the secretion of this organ.

  -=-=-=-=-=-=-=-=-=-=-=-=

418. Give the structure of the glands. 419. How are the glands
arranged? 420-431. _Give the physiology of the secretory organs._ 420.
What is secretion?

  -=-=-=-=-=-=-=-=-=-=-=-=

421. The secreted fluids do not exist in that form in the blood,
but most of the elements of which they are made do exist in this
fluid, and the "vessels by which it is accomplished may well be called
the architects and chemists of the system; for out of the same
material--the blood--they construct a variety of wonderful fabrics
and chemical compounds. We see the same wonderful power possessed,
also, by vegetables; for out of the same materials the olive prepares
its oil, the cocoa-nut its milk, the cane its sugar, the poppy its
narcotic, the oak its green pulpy leaves, and its dense woody fibre.
All are composed of the same few, simple elements, arranged in
different order and proportions."

422. "In like manner we find the vessels, in animated bodies, capable
of forming all the various textures and substances which compose the
frame; the cellular tissue, the membranes, the ligaments, the
cartilages, the bones, the marrow, the muscles with their tendons, the
lubricating fluid of the joints, the pulp of the brain, the
transparent jelly of the eye; in short, all the textures of the
various organs of which the body is composed, consist of similar
ultimate elements, and are manufactured from the blood."

423. Of the agents that produce or direct the different secretions, we
have no very accurate knowledge. Some have supposed this function to
be mechanical, others a chemical process, but experiments prove that
it is dependent on nervous influence. If the nerves are divided which
are distributed to any organ, the process of secretion is suspended.
It is no uncommon occurrence, that the nature of milk will be so
changed from the influence of anger in the mother, as to cause
vomiting, colic, and even convulsions, in the infant that swallows it.
Unexpected intelligence either of a pleasant or unpleasant character,
by its influence on the nervous system, will frequently destroy the
appetite. Sometimes mental agitation, as fear, will cause a cold sweat
to pervade the surface of the body.

  -=-=-=-=-=-=-=-=-=-=-=-=

421. What is said respecting secreted substances? Do vegetables
possess the property of secretion? 422. From what are the various
textures formed? 423. Have we accurate knowledge of the agents that
produce secretion?

  -=-=-=-=-=-=-=-=-=-=-=-=

424. Secretions are constantly maintained, during life, from the
serous membrane, by the action of the internal exhalants. The fluid
which is exhaled bears some resemblance to the serum of the blood. Its
use is to furnish the organs, which are surrounded by this membrane,
with a proper degree of moisture, and thus enables them to move easily
on each other, as those within the chest and abdomen.

425. The cellular tissue exhales a serous fluid, and when it becomes
excessive in quantity, general dropsy is produced. Fat is another
secretion, which is thrown out, in a fluid state, from the cellular
membrane. It is deposited in little cells, and exists in the greatest
abundance between the skin and the muscles. Its use seems to be, to
form a cushion around the body for its protection; to furnish
nutriment for the system when food cannot be taken; to supply the
carbon and hydrogen necessary to sustain the generation of heat, when
these articles of combustion are not otherwise furnished. The
_med´ul-la-ry_ substance, (marrow,) in the cavities of the long bones,
is very much like fat.

_Observation._ During sickness, if there is not emaciation or
absorption of this secretion, it is considered an unfavorable symptom,
because it indicates a want of power in the absorbing system, which is
among the last to be affected.

  -=-=-=-=-=-=-=-=-=-=-=-=

How is it proved that secretion depends on nervous influence? 424.
What is said of the secretions from the serous membrane? 425. From
what tissue is a serous fluid exhaled? What is the effect when this
fluid becomes excessive in quantity? What is fat? Its use? What is
marrow?

  -=-=-=-=-=-=-=-=-=-=-=-=

426. The mucous secretion is a transparent, viscid fluid which is
secreted by those membranes that line the cavities of the body, which
have an external communication, as the trachea and alimentary canal.
This secretion serves to protect these parts from the influence of the
air, and concurs, by means of its peculiar properties, in the
performance of their functions. 427. There are two external
secretions, namely, one from the skin, called perspiration, and the
other from the lungs. The cutaneous exhalation, or transpiration[14]
exists in two forms, called sensible perspiration (sweat) and
insensible perspiration. The pulmonary exhalation is the most
important and universal, and closely resembles that of the skin.

  [14] _Transpiration_ is a term often used generically, to signify the
       passage of fluids or gases through membranes, internally or
       externally; but _perspiration_ is a specific term, signifying
       transpiration on to the external surface.

428. The follicles are found only in the skin and mucous membrane.
They secrete an oily, unctuous substance, which mixes with the
transpiration, and lubricates the skin. At the root of each hair there
is a minute follicle, which secretes the fluid that oils the hair. The
wax in the passage of the ear is secreted from these bodies.

429. All the blood distributed to the different glands is similar in
composition and character; but the fluids secreted by them, vary in
appearance in a remarkable degree. The office of the glands appears to
be principally to form different secretions. Thus the salivary glands
secrete the insipid saliva; the lachrymal glands, the saline tears;
the liver, the yellow, ropy bile; and the kidneys, the acrid urine.

  -=-=-=-=-=-=-=-=-=-=-=-=

426. What is said relative to the mucous secretion? 427. Name the
external secretions. 428. Give the office of the follicles. 429. What
appears to be the principal office of the glands? 430. Mention a
secretion produced in a particular emergency.

  -=-=-=-=-=-=-=-=-=-=-=-=

430. Some secretions are evidently produced only in particular
emergencies, as is seen in the increased secretion of bony matter when
a limb is broken.

431. When any substance which is not demanded for nutrition, or does
not give nourishment to the system, is imbibed by the lymphatic
vessels, and conveyed into the blood, it is eliminated in the
secretions.

_Illustration._ A few years since, a poor inebriate was carried to a
London hospital in a state of intoxication. He lived but a few hours.
On examining his brain, nearly half a gill of fluid, strongly
impregnated with gin, was found in the cavities of this organ. This
was secreted from the vessels of the brain.


HYGIENE OF THE SECRETORY ORGANS.

432. _Unless the secretions are regularly maintained, disease will be
the ultimate result._ Let the secretions from the skin be suppressed,
and fever or some internal inflammation will follow. If the bile is
impeded, digestion will be impaired. If any other secretion is
suppressed, it will cause a derangement of the various internal
organs.

_Observation._ Ardent spirits derange the secretions, and change the
structure of the brain. This is one reason why inebriates do not
generally live to advanced age.

433. _The quantity of blood influences the character of the
secretions._ If it is lessened to any great extent, the secretions
will be lessened as well as changed in character.

_Illustration._ When a person has lost a considerable quantity of
blood, there is a sensation of thirst in the fauces, attended with a
cold, pale, dry skin. When reaction comes on, the perspiration is
cold, attended with nausea, and sometimes vomiting.

  -=-=-=-=-=-=-=-=-=-=-=-=

431. What becomes of those substances imbibed by the lymphatics that
do not give nourishment to the body. 432-437. _Give the hygiene of the
secretory organs._ 432. What effect on the system when the secretions
are not regularly maintained? 433. Does the quantity of blood
influence the secretions? Give an illustration.

  -=-=-=-=-=-=-=-=-=-=-=-=

434. _The secretory organs require the stimulus of pure blood._ If
this fluid is vitiated, the action of the secretory organs will be
more or less modified. Either the quantity will be affected or the
quality will be altered.

_Observation._ The impurity of the blood arising from the inhalation
of the vitiated air of sleeping rooms, diminishes and changes the
character of the secretions of the mouth and stomach. This accounts
for the thirst, coated tongue, and disagreeable taste of the mouth
when impure air is breathed during sleep. The disease it induces, is
indigestion or dyspepsia.

435. _The amount of action modifies the condition of the secretory
organs._ When a secretory organ is excessively stimulated, its vigor
and energy are reduced. The subsequent debility may be so great as to
suppress or destroy its functional power.

_Illustrations._ 1st. In those sections of the country where flax is
spun on a "foot-wheel," it is not unfrequent that the spinners moisten
the thread with the secretions of the mouth. This seems to operate
economically for a time, but debility of the salivary organs soon
follows, which incapacitates them from supplying saliva sufficient to
moisten the food, producing in a short time disease of the digestive
organs.

2d. The habit of continual spitting, which attends the chewing of
tobacco and gums, and other substances, between meals, induces
debility, not only of the salivary glands, but of the system
generally.

436. _One secretory organ may do the office of another._ This
increased action of a secretory organ may be sustained for a limited
time without permanent injury, but, if long continued, a diseased
action of the organ will follow. Of morbid secretions we have examples
in the ossification of the valves of the heart, cancerous and other
tumors.

  -=-=-=-=-=-=-=-=-=-=-=-=

434. What is the effect of impure blood on the secretory organs? 435.
What results from stimulating excessively a secretory organ? How is
this illustrated? 436. What is the effect when one secretory organ
performs the office of another?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ In the evenings of the warm season, a chill upon the
impressible skin, that suppresses the perspiration, is frequently
followed by a diarrhoea, dysentery, or cholera morbus. These can be
prevented by avoiding the chill. An efficient means of relief, is
immediately to restore the skin to its proper action.

437. _The secretions are much influenced by the mind._ How this is
effected, it is difficult to explain; but many facts corroborate it.
Every one has felt an increased action of the tear-glands from
distressing feelings. Cheerfulness of disposition and serenity of the
passions are peculiarly favorable to the proper performance of the
secretory function. From this we may learn how important it is to
avoid such things as distract, agitate, or harass us.

_Observation._ In fevers and other diseases, when the skin, mouth, and
throat are dry from a suppression of the secretions, let the mind of
the patient be changed from despondency to hope, and the skin and the
membrane that lines the mouth and throat will exhibit a more moist
condition, together with a general improvement of the vital organs of
the system. Consequently, all just encouragement of the restoration to
health should be given to a sick person.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give examples of morbid secretions. What is one cause of dysentery and
cholera morbus? How can these affections he relieved? 437. Show the
influence of the mind on the secretions. Mention instances of its
influence.

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXII.

NUTRITION.


438. NUTRITION is the vital act by which the different parts of the
body renew the materials of which they are composed. Digestion,
circulation, absorption, and respiration, are but separate links in
the chain of nutrition, which would be destroyed by the absence of any
one of them.

439. The nutritive process is also a kind of secretion, by which
particles of matter are separated from the blood and conveyed with
wonderful accuracy to the appropriate textures. The function of the
nutrient vessels antagonizes those of absorption: while one system is
constructing, with beautiful precision, the animal frame, the other is
diligently employed in pulling down this complicated structure.

440. This ever-changing state of the body is shown by giving animals
colored matter, mixed with their food, which in a short time tinges
their bones with the same color as the matter introduced. Let it be
withdrawn, and in a few days the bones will assume their former
color--evidently from the effects of absorption. The changeful state
of the body is further shown by the losses to which it is subjected;
by the necessity of aliment; by the emaciation which follows
abstinence from food.

  -=-=-=-=-=-=-=-=-=-=-=-=

438-454. _What remarks respecting nutrition?_ 438. What is nutrition?
439. What is said of the nutritive process? The function of the
nutrient vessels? 440. Give a proof of the ever-changing state of the
body. Give other instances illustrative of the changeful state of the
body.

  -=-=-=-=-=-=-=-=-=-=-=-=

441. Every part of the body is subject to this continual change of
material, yet it is effected with such regularity, that the size,
shape, and appearance, of every organ is preserved; and after an
interval of a few years, there may not remain a particle of matter
which existed in the system at a former period. Notwithstanding this
entire change, the personal identity is never lost.

442. Many calculations have been made to determine in what length of
time the whole body is renewed. Some have supposed that it is
accomplished in four years; others have fixed the period at seven
years; but the time of the change is not definite, as was supposed by
a genuine son of the Emerald Isle, who had been in America _seven
years and three months_, and consequently maintained that he was a
native American.

_Observation._ India ink, when introduced into the skin, is not
removed; hence some assert that this tissue is an exception to the
alternate deposition and removal of its atoms. The ink remains because
its particles are too large to be absorbed, and when in the skin it is
insoluble.

443. "Those animals which are most complicated in their structure, and
are distinguished by the greatest variety of vital manifestations, are
subject to the most rapid changes of matter. Such animals require more
frequent and more abundant supplies of food; and, in proportion as
they are exposed to the greater number of external impressions, will
be the rapidity of this change of matter."

444. "Animals may be situated so that they lose nothing by secretion;
consequently, they will require no nutriment. Frogs have been taken
from fissures in solid lime rock, which were imbedded many feet below
the surface of the earth, and, on being exposed to the air, exhibited
signs of life."

  -=-=-=-=-=-=-=-=-=-=-=-=

441. Why is the personal identity never lost in the change of
materials, which is unceasing in the system? 442. Give the opinion of
physiologists respecting the time required for the renewal of the
whole body. What exception to the changing state Of the different
textures? 443. What animals are subject to the most rapid changes of
material? 444. May animals be situated so that they require no
nutriment? What is related of frogs?

  -=-=-=-=-=-=-=-=-=-=-=-=

445. The renovation of the bone, muscle, ligament, tendon, cartilage,
fat, nerve, hair, &c., is not perfected merely by the general
circulation of the fluid which is expelled from the left side of the
heart, but through the agency of a system of minute vessels, which,
under ordinary circumstances, cannot be seen by the eye, even when
aided by the microscope; still, minute as they are, the function of
these agents is necessary to the continuance of life. They are the
smallest capillary vessels.

446. "As the blood goes the round of the circulation, the nutrient
capillary vessels select and secrete those parts which are similar to
the nature of the structure, and the other portions pass on; so that
every tissue imbibes and converts to its own use the very principles
which it requires for its growth; or, in other words, as the vital
current approaches each organ, the particles appropriate to it feel
its attractive force,--obey it,--quit the stream,--mingle with the
substance of its tissue,--and are changed into its own true and proper
nature."

447. Thus, if a bone is broken, a muscle or a nerve wounded, and, if
the system is in a proper state of health, the vital economy
immediately sets about healing the rupture. The blood, which flows
from the wounded vessels, coagulates in the incision, for the double
purpose of stanching the wound, and of forming a matrix for the
regeneration of the parts. Very soon, minute vessels shoot out from
the living parts into the coagulum of the blood, and immediately
commence their operations, and deposit bony matter, where it is
required to unite fractured bones, and nervous substance to heal the
wounded nerve, &c.

  -=-=-=-=-=-=-=-=-=-=-=-=

445. Show how the renovation of the bones, muscles, &c., is perfected.
446. What is said of the office of the nutrient capillary vessels?
447. When a bone is fractured, by what process is it healed?

  -=-=-=-=-=-=-=-=-=-=-=-=

448. But the vital economy seems not to possess the power of
reproducing the muscles and true skin, and therefore, when these parts
are wounded, the rupture is repaired by a gelatinous substance, which
gradually becomes hard, and sometimes assumes something of a fibrous
appearance. It so perfectly unites the divided muscle, however, as to
restore its functional power. When the cuticle is removed, it is
reproduced and no scar remains; but, when the true skin is destroyed,
a scar is formed.

449. It is not uncommon that the nutrient arteries have their action
so much increased in some parts, as to produce preternatural growth.
Sometimes the vessels whose function it is to deposit fat, are
increased in action, and wens of no inferior size are formed. Again,
there may be a deposition of substances unlike any known to exist in
the body. Occasionally, these nutrient arteries of a part take on a
new action, and not only deposit their ordinary substance, but others,
which they have not heretofore secreted, but which are formed by
vessels of other parts of the body. It is in this way that we account
for the bony matter deposited in the valves of the heart and brain,
also the chalky deposits around the finger-joints.

450. In infancy and childhood, the function of nutrition is very
active; a large amount of food is taken, to supply the place of what
is lost by the action of the absorbents, and also to contribute to the
growth of the body. In middle age, nutrition and absorption are more
equal; but in old age, the absorbents are more active than the
nutrient vessels. The size, consequently, diminishes, the parts become
weaker, the bones more brittle, the body bends forward, and every
function exhibits marks of decay and dissolution.

451. A striking instance of active absorption in middle age was
exhibited in the person of Calvin Edson, of Vermont, who was exhibited
in the large towns of New England, as the "living skeleton." In early
manhood he was athletic, and weighed one hundred and sixty pounds; but
the excessive action of the absorbents over the nutrient vessels,
reduced his weight, in the interval of eighteen years, to sixty
pounds.

  -=-=-=-=-=-=-=-=-=-=-=-=

448. What occurs when a muscle is divided? 449. State some of the
results of an increased action of the nutrient arteries. 450. When is
nutrition most active? How in middle age? How in old age? 451. Relate
a striking instance of active absorption in middle age.

  -=-=-=-=-=-=-=-=-=-=-=-=

452. Instances, on the other hand, have occurred, of the action of the
nutrient vessels exceeding, in an extreme degree, those of absorption;
as in the person of a colored girl, thirteen years of age, who was
exhibited in New York in the summer of 1840. She was of the height of
misses at that age, but weighed five hundred pounds. Several cases are
on record of persons weighing eight hundred pounds.

453. As already mentioned, the blood is the nutritive fluid of
animals. When this fluid is coagulated, a thick, jelly-like mass
floats in the serum, called coagulum. This coagulated mass is composed
of fibrin, and red globulated matter. The color of the red globules is
owing to the presence of iron, though some physiologists think it
depends on an animal substance of a gelatinous character.

_Observation._ That portion of the serum which remains fluid after
coagulation by heat has taken place, is called _se-ros´i-ty_. It is
more abundant in the blood of old, than in that of young animals; and
it forms the "red gravy" in roasted meats.

454. The blood is not necessarily red. It may be white, as in most
fish. There is no animal in which the blood is equally red in all
parts of the body. The ligaments, tendons, and other white tissues in
man are supplied but sparingly with red blood. The fluid that supplies
these tissues is whitish.

  -=-=-=-=-=-=-=-=-=-=-=-=

452. Of excessive nutrition in early life. 453. Describe the parts
that enter into the composition of the blood. What part of the blood
forms the red gravy in roasted meats? 454. Is the blood necessarily
red? Of what color is the blood of the fish? What part of the human
system has white blood?

  -=-=-=-=-=-=-=-=-=-=-=-=


HYGIENE OF NUTRITION.

455. _Healthy nutrition requires pure blood._ If the nutrient arteries
of the bones are supplied with impure blood, they will become soft or
brittle, their vitality will be impaired, and disease will be the
ultimate result. The five hundred muscles receive another portion of
the blood. These organs are attached to, and act upon the bones. Upon
the health and contractile energy of the muscles depends the ability
to labor. Give these organs of motion impure blood, which is an
unhealthy stimulus, and they will become enfeebled, the step will lose
its elasticity, the movement of the arm will be inefficient, and every
muscle will be incapacitated to perform its usual amount of labor.

456. When the stomach, liver, and other organs subservient to the
digestion of food, are supplied with impure blood, the digestive
process is impaired, causing faintness and loss of appetite, also a
deranged state of the intestines, and, in general, all the symptoms of
dyspepsia.

457. The delicate structure of the lungs, in which the blood is or
should be purified, needs the requisite amount of pure blood to give
them vigor and health. When the blood is not of this character, the
lungs themselves lose their tone, and, even if permitted to expand
freely, have not power fully to change the impure quality of this
circulating fluid.

458. The health and beauty of the skin require that the blood should
be well purified; but, if the arteries of the skin receive vitiated
blood, pimples and blotches appear, and the individual suffers from
"humors." Drinks, made of various kinds of herbs, as well as pills
and powders, are taken for this affection. These will never have the
desired effect, while the causes of impure blood exist.

  -=-=-=-=-=-=-=-=-=-=-=-=

455-462. _Give the hygiene of nutrition._ 455. What is the effect of
impure blood upon the bones? On the muscles? 456. On the digestive
organs? 457. On the lungs? 458. What is the effect if the vessels of
the skin are supplied with vitiated blood?

  -=-=-=-=-=-=-=-=-=-=-=-=

459. If the nutrient arteries convey impure material to the brain, the
nervous and bilious headache, confusion of ideas, loss of memory,
impaired intellect, dimness of vision, and dulness of hearing, will be
experienced; and in process of time, the brain becomes disorganized,
and the brittle thread of life is broken.

_Observations._ 1st. An exertion of any organ beyond its powers,
induces weakness that will disturb the nutrition of the part that is
called into action; and it recovers its energy more slowly in
proportion to the excess of the exertion. The function of the organ
may be totally and permanently destroyed, if the exertion is extremely
violent. We sometimes see palsy produced in a muscle simply by the
effort to raise too great a weight. The sight is impaired, and total
blindness may be produced, by exposure to light too strong or too
constant. The mind may be deranged, or idiocy may follow the excess of
study or the over-tasking of the brain.

2d. When the function of an organ is permanently impaired or destroyed
by over-exertion, the nutrition of the part is rendered insufficient,
or is entirely arrested; and then the absorbents remove it wholly or
partially, as they do every thing that is no longer useful. Thus, in
palsied patients, a few years after the attack, we often find scarce
any trace of the palsied muscles remaining; they are reduced almost to
simple cellular tissue. The condition of the calf of the leg, in a
person having a club-foot, is a familiar proof of this.

460. _The blood may be made impure, by the chyle being deficient in
quantity or defective in quality._ This state of the chyle may be
produced by the food being improper in quantity or quality, or by its
being taken in an improper manner, at an improper time, and when the
system is not prepared for it. The remedy for impure blood produced in
any of these ways is to correct the injudicious method of using food.
(See Chapters XV. and XVI.)

  -=-=-=-=-=-=-=-=-=-=-=-=

459. How does impure blood affect the brain? What is the effect when
any organ is exerted beyond its powers? What is the effect when an
organ is permanently impaired? 460. How may the blood become impure?

  -=-=-=-=-=-=-=-=-=-=-=-=

461. _The blood may also be rendered impure, by not supplying it with
oxygen in the lungs, and by the carbon not being eliminated from the
system through this channel._ The remedy for "impurities of the
blood," produced in this manner, would be, to carefully reduce to
practice the directions in the chapters on the hygiene of the
respiratory organs, relative to the free movements of the ribs and
diaphragm, and the proper ventilation of rooms.

462. _A retention of the waste products of the skin produces impure
blood._ When the vessels of the skin, by which the waste, useless
material is eliminated from the system, have become inactive by
improper and inadequate clothing, or by a want of cleanliness, the
dead, injurious atoms of matter are retained in the circulatory
vessels. The only successful method of purifying the blood and
restoring health when this condition exists, is to observe the
directions given relative to clothing and bathing. (See Chapters
XXXIII. and XXXIV.)

_Observation._ If the blood has become "impure," or "loaded with
humors," (an idea generally prevalent,) it is not and cannot be
"purified" by taking patent pills, powders, drops, &c. But, on the
contrary, by observing the suggestions in the preceding paragraphs,
the blood can be freed of its impurities, and, what is of greater
importance, such "injurious humors" will be prevented.

  -=-=-=-=-=-=-=-=-=-=-=-=

461. Mention another means by which the blood may be made impure. How
remedied? 462. What is the effect of want of cleanliness upon the
blood? What is said respecting "humors" in the blood?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 88. A front view of the organs within the chest and
abdomen. 1, 1, 1, 1, The muscles of the chest. 2, 2, 2, 2, The ribs. 3,
3, 3, The upper, middle, and lower lobes of the right lung. 4, 4, The
lobes of the left lung. 5, The right ventricle of the heart. 6, The left
ventricle. 7, The right auricle of the heart. 8, The left auricle. 9, The
pulmonary artery. 10, The aorta. 11, The vena cava descendens. 12, The
trachea. 13, The oesophagus. 14, 14, 14, 14, The pleura. 15, 15, 15, The
diaphragm. 16, 16, The right and left lobe of the liver. 17, The
gall-cyst. 18, The stomach. 26, The spleen. 19, 19, The duodenum. 20, The
ascending colon. 21, The transverse colon. 25, The descending colon. 22,
22, 22, 22, The small intestine. 23, 23, The abdominal walls turned down.
24, The thoracic duct, opening into the left subclavian vein, (27.)]



CHAPTER XXIII.

THE RESPIRATORY ORGANS.


463. The nutrient portion of the food is poured into the left
subclavian vein, (24, 27, fig. 88,) at the lower part of the neck, and
is carried to the right cavities of the heart. The fluid in these
cavities consists of the chyle incorporated with the impure blood.
Neither of these two elements is fitted to promote the growth or
repair the waste of the body. They must be subjected to a process, by
which the first can be converted into blood, and the second freed of
its carbonic acid gas and water. This is effected by the _Respiratory
Organs_.


ANATOMY OF THE RESPIRATORY ORGANS.

464. The RESPIRATORY ORGANS are the _Lungs_, (lights,) the _Tra´che-a_,
(windpipe,) the _Bronch´i-a_, (subdivisions of the trachea,) and the
_Air-Ves´i-cles_, (air-cells at the extremities of the bronchia.) The
_Di´a-phragm_, (midriff,) _Ribs_, and several _Muscles_, also aid in the
respiratory process.

465. The LUNGS are conical organs, one on each side of the chest,
embracing the heart, (fig. 88,) and separated from each other by a
membranous partition. The color of the lungs is a pinkish gray,
mottled, and variously marked with black. Each lung is divided into
lobes, by a long and deep fissure, which extends from the posterior
surface of the upper part of the organ, downward and forward, nearly
to the anterior angle of the base. In the right lung, the upper lobe
is subdivided by a second fissure. This lung is larger and shorter
than the left. It has three lobes, while the left has only two.

  -=-=-=-=-=-=-=-=-=-=-=-=

463. What fluids are conveyed into the right cavities of the heart?
What is necessary before they can be adapted to the wants of the body?
By what organs are these changes effected? 464-474. _Give the anatomy
of the respiratory organs._ 464. Name the respiratory organs. What
organs also aid in the respiratory process? 465. Describe the lungs.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 89. A back view of the heart and lungs. The posterior
walls of the chest are removed. 1, 2, 3, The upper, middle, and lower
lobes of the right lung. 8, 9, 10, The two lobes of the left lung. 6, 13,
The diaphragm. 7, 7, 14, 14, The pleura that lines the ribs. 4, 11, The
pleura that lines the mediastine. 5, 12, 12, The portion of the pleura
that covers the diaphragm. 15, The trachea, 16, The larynx. 19, 19, The
right and left bronchia. 20, The heart. 29, The lower part of the spinal
column.]

  -=-=-=-=-=-=-=-=-=-=-=-=

Explain fig. 89.

  -=-=-=-=-=-=-=-=-=-=-=-=

466. Each lung is enclosed, and its structure maintained by a serous
membrane, called the _pleu´ra_, which invests it as far as the root,
and is thence reflected upon the walls of the chest. The lungs,
however, are on the outside of the pleura, in the same way as the head
is on the outside of a cap doubled upon itself. The reflected pleuræ
in the middle of the thorax form a partition, which divides the chest
into two cavities. This partition is called the _me-di-as-ti´num_.

[Illustration: Fig. 90. The heart and lungs removed from the chest, and
the lungs freed from all other attachments. 1, The right auricle of the
heart. 2, The superior vena cava. 3, The inferior vena cava. 4, The right
ventricle. 5, The pulmonary artery issuing from it. _a_, _a_, The
pulmonary artery, (right and left,) entering the lungs. _b_, _b_,
Bronchia, or air-tubes, entering the lungs. _v_, _v_, Pulmonary veins,
issuing from the lungs. 6, The left auricle. 7, The left ventricle. 8,
The aorta. 9, The upper lobe of the left lung. 10, Its lower lobe. 11,
The upper lobe of the right lung. 12, The middle lobe. 13, The lower
lobe.]

_Observation._ When this membrane that covers the lungs, and also
lines the chest, is inflamed, the disease is called "pleurisy."

  -=-=-=-=-=-=-=-=-=-=-=-=

466. By what are the lungs enclosed? What is the relative position of
the lungs and pleura? What is said of the reflected pleuræ? Explain
fig. 90. What part of the lungs is affected in pleurisy?

  -=-=-=-=-=-=-=-=-=-=-=-=

467. The lungs are composed of the ramifications of the bronchial
tubes, which terminate in the bronchial cells, (_air-cells_,)
lymphatics, and the divisions of the pulmonary artery and veins. All
of these are connected by cellular tissue, which constitutes the
_pa-ren´chy-ma_. Each lung is retained in its place by its _root_,
which is formed by the pulmonary arteries, pulmonary veins, and
bronchial tubes, together with the bronchial vessels and pulmonary
nerves.

468. The TRACHEA extends from the larynx, of which it is a continuation,
to the third dorsal vertebra, where it divides into two parts, called
bronchia. It lies anterior to the spinal column, from which it is
separated by the oesophagus.

469. The BRONCHIA proceed from the bifurcation, or division of the
trachea, to their corresponding lungs. Upon entering the lungs, they
divide into two branches, and each branch divides and subdivides, and
ultimately terminates in small sacs, or cells, of various sizes, from
the twentieth to the hundredth of an inch in diameter. So numerous are
these bronchial or air-cells, that the aggregate extent of their
lining membrane in man has been computed to exceed a surface of 20,000
square inches, and Munro states that it is thirty times the surface of
the human body.

_Illustration._ The trachea may be compared to the trunk of a tree;
the bronchia, to two large branches; the subdivisions of the bronchia,
to the branchlets and twigs; the air-cells, to the buds seen on the
twigs in the spring.

470. The AIR-VESICLES and small bronchial tubes compose the largest
portions of the lungs. These, when once inflated, contain air, under
all circumstances, which renders their specific gravity much less than
water; hence the vulgar term, _lights_, for these organs. The trachea
and bronchial tubes are lined by mucous membrane. The structure of
this membrane is such, that it will bear the presence of pure air
without detriment, but not of other substances.

  -=-=-=-=-=-=-=-=-=-=-=-=

467. Of what are the lungs composed? How retained in place? 468. Where
is the trachea situated? 469. Describe the bronchia. What is the
aggregate extent of the lining membrane of the air-cells? To what may
the trachea and its branches be compared? 470. What is said of the
air-cells and bronchial tubes?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 91. A representation of the larynx, trachea,
bronchia, and air-cells. 1, 1, 1, An outline of the right lung. 2, 2, 2,
An outline of the left lung. 3, The larynx 4, The trachea. 5, The right
bronchial tube. 6, The left bronchial tube. 7, 7, 7, 8, 8, 8, The
subdivisions of the right and left bronchial tubes. 9, 9, 9, 9, 9, 9,
Air-cells.]

  -=-=-=-=-=-=-=-=-=-=-=-=

What membrane lines the trachea and its branches? What is peculiar in
its structure? What does fig. 91 represent?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ The structure of the trachea and lungs may be
illustrated, by taking these parts of a calf or sheep and inflating
the air-vesicles by forcing air into the windpipe with a pipe or
quill. The internal structure may then be seen by opening the
different parts.

471. The lungs, like other portions of the system, are supplied
with nutrient arteries and nerves. The nervous filaments that
are distributed to these organs are in part from the tenth pair,
(par vagum,) that originates in the brain, and in part from the
sympathetic nerve. The muscles that elevate the ribs and the
diaphragm receive nervous fibres from a separate system, which is
called the respiratory.

[Illustration: Fig. 92. 1, A bronchial tube. 2, 2, 2, Air-vesicles. Both
the tube and vesicles are much magnified. 3, A bronchial tube and
vesicles laid open.]

_Observation._ When the mucous membrane of a few of the larger
branches of the windpipe is slightly inflamed, it is called a "cold;"
when the inflammation is greater, and extends to the lesser air-tubes,
it is called _bronch-i´tis_. When the air-cells and parenchyma become
inflamed, it is called inflammation of the lungs. Coughing is a
violent expulsory effort by which air is suddenly forced through the
bronchia and trachea to remove offending matter.

  -=-=-=-=-=-=-=-=-=-=-=-=

How may the structure of the trachea and its branches be illustrated?
471. Are the lungs supplied with nutrient arteries? Where are the
respiratory nerves distributed? From what source do these organs
derive their nervous filaments?

  -=-=-=-=-=-=-=-=-=-=-=-=

472. The RIBS are joined to the spinal column at their posterior
extremity; and in front, they terminate in cartilages, which unite
them to the sternum. They incline downward, from the spinal column to
the breast-bone, and form resisting walls that assist in producing the
partial vacuum necessary for inspiration.

[Illustration: Fig. 93. A section of the chest when the lungs are
inflated. 1, The diaphragm. 2, The muscular walls of the abdomen.]

[Illustration: Fig. 94. A section of the chest when the lungs are
contracted. 1, The diaphragm in common expiration. 2, 2, The muscular
walls of the abdomen. 3, The position of the diaphragm in forced
expiration.]

These engravings show the diaphragm to be more convex, and the walls
of the abdomen more flattened, when the lungs are collapsed, than when
they are inflated.

473. The DIAPHRAGM is a flexible circular partition, that separates
the respiratory from the digestive organs, and the chest from the
abdomen. Its margin is attached to the spinal column, the sternum, and
cartilages of the lower ribs. The lungs rest upon its upper surface,
while the liver and stomach are placed below it, (fig. 88.) In a
state of repose, its upper surface forms an arch, the convexity of
which is toward the chest. In forced expiration, its upper point
reaches as high as the fourth rib. In an ordinary inspiration, it is
depressed as low as the seventh rib, which increases the capacity of
the chest.

  -=-=-=-=-=-=-=-=-=-=-=-=

472. Describe the ribs. Explain figs. 93 and 94. 473. Describe the
diaphragm.

  -=-=-=-=-=-=-=-=-=-=-=-=

474. The RESPIRATORY muscles are, in general, attached at one
extremity to the parts about the shoulders, head, and upper portion
of the spinal column. From these, they run downward and forward, and
are attached, at the opposite extremity, to the sternum, clavicle,
and upper rib. Other muscles are attached at one extremity to a rib
above, and by the opposite extremity to a rib below. These fill the
spaces between the ribs, and, from their situation, are called
_in-ter-cost´al_ muscles.

_Observation._ 1st. There are several actions of common occurrence,
that are intimately connected with respiration; such as hiccough,
sneezing, &c. Hiccough is an involuntary contraction of the muscles of
respiration, particularly the diaphragm.

2d. Sneezing is a violent, involuntary contraction of the respiratory
muscles, as in hiccough. When an acrid stimulant, as snuff, is applied
to the mucous membrane of the nose, an irritation is produced which is
accompanied by a violent expulsion of air from the lungs. This is
owing to the connection between the nasal and respiratory nerves.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is its form when not in action? 474. Where do the respiratory
muscles make their attachment? What name is given to those muscles
that fill the places between the ribs? What is hiccough? What is
sneezing?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXIV.

PHYSIOLOGY OF THE RESPIRATORY ORGANS.


475. RESPIRATION, or breathing, is that process by which air is taken
into the lungs and expelled from them. The object of respiration is,
1st. To supply the system with oxygen, which is essential to the
generation of animal heat; 2d. To convert the chyle into blood. This
is done by the oxygen of the inspired air; 3d. To relieve the organs
of the body of the principal elements (carbon and hydrogen) that
compose the old and useless particles of matter. The organs of the
system, as already mentioned, are principally composed of carbon,
hydrogen, oxygen, and nitrogen.

476. By the action of the lymphatics and capillary veins, the old and
worn-out particles are conveyed into the veins of the systemic
circulation. The hydrogen, in form of watery vapor, is easily
discharged in the perspiration and other secretions. The nitrogen and
oxygen are, or may be, separated from the blood, through the agency of
several different organs; but carbon does not escape so readily. It is
probable that a part of the surplus carbon of the venous blood is
secreted by the liver; but a far greater amount passes to the lungs,
and these may be considered as special organs designed to separate
this element from the venous blood.

477. An ordinary inspiration may be accomplished by the action of the
diaphragm, and a slight elevation of the ribs. In full inspiration,
the diaphragm is not only more depressed but the ribs are evidently
elevated. To produce this effect on the ribs, two sets of muscles are
called into action. Those which are attached to the upper rib,
sternum, and clavicle, contract and elevate the lower and free
extremities of the ribs. This enlarges the cavity of the chest between
the spinal column and the sternum. But the lateral diameter, in
consequence, is only slightly increased, because the central portion
of the ribs sinks lower than their posterior extremities, or their
cartilaginous attachment to the sternum.

  -=-=-=-=-=-=-=-=-=-=-=-=

475-494. _Give the physiology of the respiratory organs._ 475. What is
respiration? What is the principal object in breathing? 476. How are
the useless atoms of matter conveyed into the veins of the systemic
circulation? How may the principal elementary substances be separated
from the blood? 477. How may an ordinary inspiration be accomplished?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 95. 6, Four of the vertebræ, to which are attached
three ribs, (7, 7, 7,) with their intercostal muscles, (8, 8.) These
ribs, in their natural position, have their anterior cartilaginous
extremity at 4, while the posterior extremity is attached to the
vertebræ, (6,) which are neither elevated nor depressed in respiration.
1, 1, and 2, 2, parallel lines, within which the ribs lie in their
natural position. If the anterior extremity of the ribs is elevated from
4 to 5, they will not lie within the line 2, 2, but will reach the line
3, 3. If two hands extend from 1, 1, to 2, 2, they will effectually
prevent the elevation of the ribs from 4 to 5, as the line 2, 2, cannot
be moved to 3, 3.]

  -=-=-=-=-=-=-=-=-=-=-=-=

What effect has a full inspiration on the ribs and diaphragm? How is
the chest enlarged between the spinal column and sternum? What is said
of the lateral diameter of the chest? Explain fig. 95.

  -=-=-=-=-=-=-=-=-=-=-=-=

478. The central portion of the ribs is raised by the action of
intercostal muscles. The first, or upper rib, has but little movement;
the second has more motion than the first, while the third has still
more than the second. The second rib is elevated by the contraction of
the muscles between it and the first. The third rib is raised by the
action of two sets of muscles; one lies between the first and second
ribs, the other between the second and third. The motion of each
succeeding rib is increased, because it is not only acted upon by the
muscles that move the ribs above, but by an additional intercostal; so
that the movement of the twelfth rib is very free, as it is elevated
by the contraction of eleven muscles.

479. The tenth rib is raised eight times as much as the second rib,
and the lateral diameter of the lower portion of the chest is
increased in a corresponding degree. At the same time, the muscular
margin of the diaphragm contracts, which depresses its central
portion; and in this way, the chest is enlarged forward, laterally,
and downward, simultaneously with the relaxation of the walls of the
abdomen.

480. The lungs follow the variations of capacity in the chest,
expanding their air-cells when the latter is enlarged, and contracting
when the chest is diminished. Thus, when the chest is expanded, the
lungs follow, and consequently a vacuum is produced in their
air-cells. The air then rushes through the mouth and nose into the
trachea and its branches, and fills the vacuum as fast as it is made.
This mechanical process constitutes _inspiration_.

481. After the expansion of the chest, the muscles that elevated the
ribs relax, together with the diaphragm. The elasticity of the
cartilages of the ribs depresses them, and the cavity of the chest is
diminished, attended by the expulsion of a portion of the air from the
lungs. At the same time, the muscles that form the front walls of the
abdominal cavity, contract, and press the alimentary canal, stomach,
and liver, upward against the diaphragm; this, being relaxed, yields
to the pressure, rises upward, and presses upon the lungs, which
retreat before it, and another portion of air is expelled from these
organs. This process is called _expiration_.

  -=-=-=-=-=-=-=-=-=-=-=-=

478. Describe the action of the intercostal muscles upon the ribs.
479. How does the elevation of the tenth rib compare with the second?
What effect has this elevation upon the lateral diameter of the chest?
480. Describe the process of inspiration. 481. Describe the process by
which the air is forced out of the lungs.

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 96. A front view of the chest and abdomen in
respiration. 1, 1, The position of the walls of the chest in inspiration.
2, 2, 2, The position of the diaphragm in inspiration. 3, 3, The position
of the walls of the chest in expiration. 4, 4, 4, The position of the
diaphragm in expiration. 5, 5, The position of the walls of the abdomen
in inspiration. 6, 6, The position of the abdominal walls in expiration.]

482. Thus it is obvious that the enlargement of the chest, or
inspiration, is produced in two ways: 1st. By the depression of the
convex portion of the diaphragm; 2d. By the elevation of the ribs. On
the contrary, the contraction of the chest, or expiration, is
produced by the depression of the ribs, and elevation of the central
part of the diaphragm. These movements are successive during life, and
constitute _respiration_.

  -=-=-=-=-=-=-=-=-=-=-=-=

Explain fig. 96. 482. In how many ways may the chest be enlarged, and
how is it accomplished? How is the contraction of the chest effected?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 97. A side view of the chest and abdomen in
respiration. 1, The cavity of the chest. 2, The cavity of the abdomen. 3,
The line of direction for the diaphragm when relaxed in expiration. 4,
The line of direction for the diaphragm when contracted in inspiration.
5, 6, The position of the front walls of the chest and abdomen in
inspiration. 7, 8, The position of the front walls of the abdomen and
chest in expiration.]

_Experiment._ Place the ear upon the chest of a person, and a
murmuring sound will be heard, somewhat like the soft sighings of the
wind through forest trees. This sound is caused by the air rushing in
and out of the lungs, and is peculiarly distinct in the child.

  -=-=-=-=-=-=-=-=-=-=-=-=

Explain fig. 97. How may the murmur of respiration be heard?

  -=-=-=-=-=-=-=-=-=-=-=-=

483. It is not easy to decide how much air is taken into the lungs at
each inspiration. The quantity, however, must vary in different
individuals, from the difference in the condition and expansion of the
lungs, together with the size of the chest. From numerous experiments,
the quantity, at an ordinary inspiration, of a common-sized man, is
fixed at forty cubic inches. It has been estimated that one hundred
and seventy cubic inches can be thrown out of the lungs by a forcible
expiration, and that there remain in the lungs two hundred and twenty
cubic inches; so that these organs, in their quiescent state, may be
considered as containing about three hundred and ninety cubic inches
of air, or more than a gallon.

484. Respiration is more frequent in females and children than in
adult men. In diseases, particularly those of the lungs, it is more
increased in frequency than the action of the heart. In health, the
smallest number of inspirations in a minute by an adult, is not less
than fourteen, and they rarely exceed twenty-five. Eighteen may be
considered an average number. The quantity of oxygen taken into the
lungs at each inspiration is about eight cubic inches, one half of
which disappears in every act of respiration.

_Observation._ Under different circumstances, however, the consumption
of oxygen varies. It is greater when the temperature is low, than when
it is high; and during digestion the consumption has been found one
half greater than when the stomach was empty.

  -=-=-=-=-=-=-=-=-=-=-=-=

483. Can it be ascertained with accuracy how much air is taken into
the lungs at each inspiration? Why not? What is the probable quantity
that an ordinary sized man inspires? How much can be thrown out of the
lungs at a forcible expiration, and how much remains in the lungs?
From these calculations, how much may they contain in their quiescent
state? 484. In whom is respiration most frequent? How in disease? How
in health? How many may be considered an average number? When is the
consumption of oxygen the greatest?

  -=-=-=-=-=-=-=-=-=-=-=-=

485. Dr. Southwood Smith has lately performed a series of very
interesting experiments, from which he deduces the following general
results: "1st. The volume of air ordinarily present in the lungs is
about twelve pints. 2d. The volume of air received by the lungs at an
ordinary inspiration is one pint. 3d. The volume of air expelled from
the lungs at an ordinary expiration, is a little less than one pint.
4th. Of the volume of air received by the lungs at one inspiration,
only one fourth part is decomposed at one action of the heart. 5th.
The quantity of blood that flows to the lungs, to be acted upon by the
air at one action of the heart, is two ounces, and this is acted on in
less than one second of time. 6th. The quantity of blood in the whole
body of the human adult, is twenty-five pounds avoirdupois, or twenty
pints. 7th. In the mutual action that takes place between the air and
blood, every twenty-four hours, the air loses thirty-seven ounces of
oxygen, and the blood fourteen ounces of carbon."

486. Apparently, atmospheric air is a simple element. But chemical
analysis shows its composition to be oxygen and nitrogen, in the
proportion of twenty-one parts of the former, and about seventy-nine
of the latter. In addition, there is a small amount of vapor of water
and carbonic acid. The pressure of this invisible, elastic fluid upon
the body of an ordinary sized adult, is estimated to equal thirty-five
thousand pounds.

487. The principal substance of a vitiated character in the
dark-colored blood is carbonic acid. And since there is no chemical
affinity between the oxygen and nitrogen of the air, the former
readily unites with some of the elements of the blood. Hence, whenever
blood is presented to the air in the lungs, the oxygen leaves the
nitrogen, and becomes mixed with the circulating fluid. (Appendix J.)

  -=-=-=-=-=-=-=-=-=-=-=-=

485. State the 1st, 2d, 3d, and 4th deductions from the experiments of
Dr. Southwood Smith. The 5th, 6th, and 7th. 486. Of what is
atmospheric air composed? What is the weight of air upon a common
sized man? 487. What is the principal substance of a vitiated
character in the dark-colored blood? What is said of the chemical
affinity between oxygen and nitrogen?

  -=-=-=-=-=-=-=-=-=-=-=-=

488. Again, carbonic acid and water have a stronger affinity for
atmospheric air than for the other elements of the blood. Consequently,
when they are brought into contact with the air in the lungs, the
carbonic acid and water leave the other constituents of the blood, and
unite with the air. In this way the bluish, or impure blood is
relieved of its impurities, and becomes the red, or pure blood,
which contains the principles so essential to life. (Appendix K.)

489. The formation of carbonic acid and water, eliminated from the
system through the lungs and skin, is explained by the following
theory: In the lungs and upon the skin the oxygen separates from the
nitrogen and unites with the blood in the capillary vessels of these
organs. The oxygen is conveyed with the blood to the capillary
arteries and veins of the different tissues of the system. In these
membranes there is a chemical union of the oxygen with the carbon and
hydrogen contained in the blood and waste atoms of the system. This
combustion, or union of oxygen with carbon and hydrogen, is attended
with the disengagement of heat, and the formation of carbonic acid and
water. (Appendix L.)

490. The following experiment will illustrate the passage of fluids
through membranes, and the different affinity of gases for each other.
Put a mixture of water and alcohol into a phial and leave it uncorked.
Both the water and alcohol have a greater affinity for air than for
each other. Alcohol has a greater affinity for the air, and will be
diffused through it more readily than the water, when there is no
intervening obstacle. But tie a piece of bladder over the mouth of the
phial, and let it stand a few days,--the water will leave the
alcohol, and pass through the membrane. By the aid of this experiment,
we shall endeavor to explain the interchange of fluids in the lungs.

  -=-=-=-=-=-=-=-=-=-=-=-=

488. What is formed when oxygen unites with carbon or hydrogen? 489.
Give the theory for the formation of carbonic acid and watery vapor
thrown out of the system. 490. Illustrate the passage of fluids
through membranes, and the different affinities of gases.

  -=-=-=-=-=-=-=-=-=-=-=-=

491. The walls of the air-vesicles, and coats of the blood-vessels,
are similar, in their mechanical arrangement, to the membranous
bladder in the before described experiment. As the oxygen of the air
has greater affinity for blood than for nitrogen, so it permeates the
membranes that intervene between the air and blood more readily than
the nitrogen. As the carbonic acid and water have a greater affinity
for air than for the other elements of the blood, so they will also
pass through the walls of the blood-vessels and air-cells more readily
than the other elements of the dark-colored blood.

[Illustration: Fig. 98. 1, A bronchial tube divided into three branches.
2, 2, 2, Air-cells. 3, Branches of the pulmonary artery, that spread over
the air-cells. Through the pulmonary artery the dark, impure blood is
carried to the air-cells of the lungs. 4, Branches of the pulmonary vein,
that commence at the minute terminations of the pulmonary artery. Through
the pulmonary vein the red blood is returned to the heart.]

492. As the impure blood is passing in the minute vessels over the
air-cells, the oxygen passes through the thin coats of the air-cells
and blood-vessels, and unites with the blood. At the same time, the
carbonic acid and water leave the blood, and pass through the coats of
the blood-vessels and air-cells, and mix with the air in the cells.
These are thrown out of the system every time we breathe. This
interchange of products produces the change in the color of the
blood.

  -=-=-=-=-=-=-=-=-=-=-=-=

Explain fig. 98. 492. How and where is the blood changed?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Experiment._ Fill a bladder with dark blood drawn from any animal.
Tie the bladder closely, and suspend it in the air. In a few hours,
the blood next to the membrane will have become of a bright red color.
This is owing to the oxygen from the air passing through the bladder,
and uniting with the blood, while the carbonic acid has escaped
through the membrane.

[Illustration: Fig. 99. An ideal view of the pulmonary circulation. 1, 1,
The right lung. 2, 2, The left lung. 3, The trachea. 4, The right
bronchial tube. 5, The left bronchial tube. 6, 6, 6, 6, Air-cells. 7, The
right auricle. 8, The right ventricle. 9, The tricuspid valves. 10, The
pulmonary artery. 11, The branch to the right lung. 12, The branch to the
left lung. 13, The right pulmonary vein. 14, The left pulmonary vein. 15,
The left auricle. 16, The left ventricle. 17, The mitral valves.]

493. The presence of carbonic acid and watery vapor in the expired
air, can be proved by the following experiments: 1st. Breathe into
lime-water, and in a few minutes it will become of a milk-white color.
This is owing to the carbonic acid of the breath uniting with the
lime, forming the _carbonate of lime_. 2d. Breathe upon a cold, dry
mirror for a few minutes, and it will be covered with moisture. This
is condensed vapor from the lungs. In warm weather, this watery vapor
is invisible in the expired air, but in a cold, dry morning in winter,
the successive jets of vapor issuing from the mouth and nose are
sufficiently obvious.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give the experiment showing that oxygen changes the dark-colored blood
to a bright red color. What is represented by fig. 99? 493. How can
the presence of carbonic acid in the lungs be proved?

  -=-=-=-=-=-=-=-=-=-=-=-=

494. From the lungs are eliminated other impurities beside carbonic
acid, the perceptible quality of which is various in different
persons. The offensive breath of many persons may be caused by decayed
teeth, or the particles of food that may be retained between them, but
it often proceeds from the secretion, in the lungs, of certain
substances which previously existed in the system.

_Illustration._ When spirituous liquors are taken into the stomach,
they are absorbed by the veins and mixed with the dark-colored blood,
in which they are carried to the lungs to be expelled from the body.
This will explain the fact, which is familiar to most persons, that
the odor of different substances is perceptible in the breath, or
expired air, long after the mouth is free from these substances.

  -=-=-=-=-=-=-=-=-=-=-=-=

How the watery vapor? 494. Are there other excretions from the lungs?
Give the illustration.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Note._ Let the anatomy and physiology of the respiratory organs be
reviewed from figs. 96, 97, and 99, or from anatomical outline plates
Nos. 5 and 7.



CHAPTER XXV.

HYGIENE OF THE RESPIRATORY ORGANS.


495. For man to enjoy the highest degree of health, it is necessary
that the impure "venous" blood be properly changed. As this is
effected in the lungs by the action of the air, it follows that this
element, when breathed, should be pure, or contain twenty-one per
cent. of oxygen to about seventy-nine per cent. of nitrogen.

496. The volume of air expelled from the lungs is somewhat less than
that which is inspired. The amount of loss varies under different
circumstances. An eightieth part of the volume taken into the lungs,
or half a cubic inch, may be considered an average estimate.

497. _The quality and purity of the air is affected by every
respiration._ 1st. The quantity of oxygen is diminished. 2d. The
amount of carbonic acid is increased. 3d. A certain proportion of
watery vapor is ejected from the lungs in the expired air. Of the
twenty-one parts of oxygen in the inspired air, only eighteen parts
are expired, while the carbonic acid and watery vapor are increased
about four per cent. The quantity of nitrogen is nearly the same in
the expired as in the inspired air.

_Observation._ It is now fully ascertained that while the chemical
composition of the blood is essentially changed, its weight remains
the same, as the carbon and hydrogen discharged are equal to the
united weight of the oxygen and nitrogen absorbed.

  -=-=-=-=-=-=-=-=-=-=-=-=

495-546. _Give the hygiene of the respiratory organs._ 495. What is
necessary that man enjoy the highest degree of health? 496. How does
the volume Of expired air compare with that which was inspired? Does
this loss vary, and what is an average estimate? 497. How is the
purity of the air affected by respiration? How is the inhaled oxygen
affected? What effect on the carbonic acid and watery vapor? On the
nitrogen? What is said respecting the weight of the blood?

  -=-=-=-=-=-=-=-=-=-=-=-=

498. If one fourth part of the volume of air received by the lungs at
one inspiration is decomposed at one "beat" of the heart, it might be
supposed that if the expired air be again received into the lungs, one
half of the oxygen would be consumed, and, in a similar ratio, if
re-breathed four times, all the oxygen would be consumed. But it does
not follow, if the air is thus re-breathed, that the same changes will
be effected in the lungs. For air that has been inspired does not part
with its remaining oxygen as freely as when it contains the proper
amount of this life-giving element, and thus the changes in the impure
blood are not so completely effected.

_Illustration._ In the process of dyeing, each successive article
immersed in the dye weakens it; but it does not follow that the dye
each time is affected in the same degree, or that the coloring matter
by repeated immersions can be wholly extracted. The same principle
applies to the exchange of oxygen and carbonic acid gas in the lungs.

499. _If the inspired air is free from moisture and carbonic acid,
these substances contained in the blood will be more readily imparted
to it._ When the air is loaded with vapor, they are removed more
slowly; but if it is saturated with moisture, no vapor will escape
from the blood through the agency of the lungs. This may be
illustrated by the following experiment: Take two and a half pounds of
water, add to it half a pound of common salt, (chloride of sodium,)
and it will readily mix with the water; and to this solution add the
same quantity of salt, and it will be dissolved more slowly. Again,
add more salt, and it will remain undissolved, as the water has become
saturated by the pound before dissolved.

  -=-=-=-=-=-=-=-=-=-=-=-=

498. Does air that is re-breathed freely impart its oxygen? Why? 499.
What is the effect on the blood when the air is free from vapor and
carbonic acid? When loaded with vapor? When saturated? How is this
illustrated?

  -=-=-=-=-=-=-=-=-=-=-=-=

500. The principle in this experiment is analogous to that of the
union between carbonic gas and atmospheric air. Allen and Pepy showed
by experiment, that air which had been once breathed, contained eight
and a half per cent. of carbonic acid. They likewise showed, that no
continuance of the respiration of the same air could make it take up
more than ten per cent. This is the point of saturation.

_Experiment._ Sink a glass jar that has a stop-cock, or one with a
glass stopper, into a pail of water, until the air is expelled from
the jar. Fill the lungs with air, and retain it in the chest a short
time, and then breathe into the jar, and instantly close the
stop-cock. Close the opening of the jar that is under the water with a
piece of paper laid on a plate of sufficient size to cover the
opening, invert the jar, and sink into it a lighted candle. The flame
will be extinguished as quickly as if put in water.[15] Remove the
carbonic acid by inverting the jar, and place a lighted candle in it,
and the flame will be as clear as when out of the jar.

  [15] As a substitute for a jar with a stop-cock, take a piece of lead
       pipe bent in the form of a siphon, and insert it in the mouth
       of a reversed jar. This experiment is as conclusive whether the
       air is inhaled once only or breathed many times.

_Observations._ 1st. It is familiarly known that a taper will not burn
where carbonic acid exists in any considerable quantity, or when there
is a marked deficiency of oxygen. From this originated the judicious
practice of sinking a lighted candle into a well or pit before
descending into it. If the flame is extinguished, respiration cannot
there be maintained, and life would be sacrificed should a person
venture in, until the noxious air is removed.

  -=-=-=-=-=-=-=-=-=-=-=-=

500. What did the experiments of Allen and Pepy show? How can the
presence of carbonic gas in the expired air be demonstrated? State
observation 1st. Observation 2d.

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. It is the action of carbonic acid upon the respiratory organs,
that gives rise to a phenomenon frequently seen in mines and caves. A
man may enter these subterranean rooms, and feel no inconvenience in
breathing; but the dog that follows him, falls apparently dead, and
soon dies if not speedily removed to pure air. This arises from the
fact that this gas is heavier than air, and sinks to the bottom of the
room or cave.

3d. While it is true that carbonic acid possesses properties that
render it unfit to be breathed, it is, notwithstanding, productive of
very agreeable effects, when conveyed into the stomach. It forms the
sparkling property of mineral waters, and fills the bubbles that rise
when beer or cider is fermenting.

501. _Pure atmospheric air is best adapted to a healthy action of the
system._ As the air cannot be maintained pure under all circumstances,
the question may be asked, To what degree may the air be vitiated and
still sustain life? and what is the smallest quantity of pure air a
person needs each minute to maintain good health? Birnan says, that
air which contains more than three and a half per cent. of carbonic
acid is unfit for respiration, and, as air once respired contains
eight and a half per cent. of carbonic acid, it clearly shows that it
is not fitted to be breathed again.

502. No physiologist pretends that less than seven cubic feet of air
are adequate for a man to breathe each minute, while Dr. Reid allows
ten feet. The necessity of fifteen or twenty times the amount of air
actually taken into the lungs, arises from the circumstance, that the
expired air mixes with and vitiates the surrounding element that has
not been inhaled.

503. _The quantity of air which different persons actually need,
varies._ The demand is modified by the size, age, habits, and
condition of the body. A person of great size who has a large quantity
of blood, requires more air than a small man with a less amount of
circulating fluid. Individuals whose labor is active, require more air
than sedentary or idle persons, because the waste of the system is
greater. On the same principle, the gormandizer needs more of this
element than the person of abstemious habits. So does the growing lad
require more air than an adult of the same weight, for the reason that
he consumes more food than a person of mature years. Habit also exerts
a controlling influence. A man who works in the open air suffers more
when placed in a small, unventilated room, than one who is accustomed
to breathe the confined air of workshops.

  -=-=-=-=-=-=-=-=-=-=-=-=

Observation 3d. 501. What questions may be asked respecting the
inspired air? Give the remark of Birnan. 502. How many cubic feet of
air are adequate for a man to breathe each minute? How much does Dr.
Reid allow? 503. Mention some reasons why different persons do not
require the same amount of air.

  -=-=-=-=-=-=-=-=-=-=-=-=

504. _Air, in which lamps will not burn with brilliancy, is unfitted
for respiration._ In crowded rooms, which are not ventilated, the air
is vitiated, not only by the abstraction of oxygen and the deposition
of carbonic acid, but by the excretions from the skin and lungs of the
audience. The lamps, under such circumstances, emit but a feeble
light. Let the oxygen gas be more and more expended, and the lamps
will burn more and more feebly, until they are extinguished.

_Illustrations._ 1st. The effects of breathing the same air again and
again, are well illustrated by an incident that occurred in one of our
halls of learning. A large audience had assembled in an ill-ventilated
room, to listen to a lecture; soon the lamps burned so dimly that the
speaker and audience were nearly enveloped in darkness. The
oppression, dizziness, and faintness experienced by many of the
audience induced them to leave, and in a few minutes after, the lamps
were observed to rekindle, owing to the exchange of pure air on
opening the door.

  -=-=-=-=-=-=-=-=-=-=-=-=

How is it with the laborer? With the gormandizer? With the person that
works in the open air? 504. What effect has impure air on a burning
lamp? Give the illustration of the effects of impure air on lighted
lamps.

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. In the "Black Hole of Calcutta," one hundred and forty-six
Englishmen were shut up in a room eighteen feet square, with only two
small windows on the same side to admit air. On opening this dungeon,
ten hours after their imprisonment, only twenty-three were alive. The
others had died from breathing impure air.

505. _Air that has become impure from the abstraction of oxygen, an
excess of carbonic acid, or the excretions from the lungs and skin,
has a deleterious effect on the body._ When this element is vitiated
from the preceding causes, it prevents the proper arterialization, or
change in the blood. For this reason, pure air should be admitted
freely and constantly into work-shops and dwelling-houses, and the
vitiated air permitted to escape. This is of greater importance than
the warming of these apartments. We can compensate for the deficiency
of a stove, by an extra garment or an increased quantity of food; but
neither garment, exercise, nor food will compensate for pure air.

506. _School-rooms should be ventilated._ If they are not, the pupils
will be restless, and complain of languor and headache. Those
unpleasant sensations are caused by a want of pure air, to give an
adequate supply of oxygen to the lungs. When pupils breathe for a
series of years such vitiated air, their life is undoubtedly
shortened, by giving rise to consumption and other fatal diseases.

_Illustration._ A school-room thirty feet square and eight feet high,
contains 7200 cubic feet of air. This room will seat sixty pupils,
and, allowing ten cubic feet of air to each pupil per minute, all the
air in the room will be vitiated in twelve minutes.

_Observation._ In all school-rooms where there is not adequate
ventilation, it is advisable to have a recess of five or ten minutes
each hour. During this time, let the pupils breathe fresh air, and
open the doors and windows, so that the air of the room shall be
completely changed.

  -=-=-=-=-=-=-=-=-=-=-=-=

Of the effects of breathing impure air. 505. In preserving health,
what is of greater importance than warming the room? 506. Why should a
school-room be ventilated? Give the illustration.

  -=-=-=-=-=-=-=-=-=-=-=-=

507. _Churches, concert halls, and all rooms designed for a collection
of individuals, should be amply ventilated._ While the architect and
workmen are assiduous in giving these public rooms architectural
beauty and splendor, by adorning the ceiling with Gothic tracery,
rearing richly carved columns, and providing carefully for the warming
of the room, it too frequently happens that no direct provision is
made for the change of that element which gives us beauty, strength,
and life.

_Illustration._ A hall sixty feet by forty, and fifteen feet high,
contains 36,000 cubic feet of air. A hall of this size will seat four
hundred persons; by allowing ten cubic feet of air to each person per
minute, the air of the room will be rendered unfit for respiration in
nine minutes.

508. _Railroad cars, cabins of steam and canal-boats, omnibuses, and
stage-coaches, require ample ventilation._ In the construction of
these public conveyances, too frequently, the only apparent design is,
to seat the greatest number of persons, regardless of the quantity and
character of the air to maintain health and even life. The character
of the air is only realized when, from the fresh, pure air, we enter a
crowded cabin of a boat or a closed coach; then the vitiated air from
animal excretions and noxious gases is offensive, and frequently
produces sickness.

509. The influence of habit is strikingly expressed by Birnan, in the
"Art of Warming and Ventilating Rooms:" "Not the least remarkable
example of the power of habit is its reconciling us to practices
which, but for its influence, would be considered noxious and
disgusting. We instinctively shun approach to the dirty, the squalid,
and the diseased, and use no garment that may have been worn by
another. We open sewers for matters that offend the sight or the
smell, and contaminate the air. We carefully remove impurities from
what we eat and drink, filter turbid water, and fastidiously avoid
drinking from a cup that may have been pressed to the lips of a
friend. On the other hand, we resort to places of assembly, and draw
into our mouths air loaded with effluvia from the lungs, skin, and
clothing of every individual in the promiscuous crowd--exhalations
offensive, to a certain extent, from the most healthy individuals; but
when arising from a living mass of skin and lungs, in all stages of
evaporation, disease, and putridity,--prevented by the walls and
ceiling from escaping--they are, when thus concentrated, in the
highest degree deleterious and loathsome."

  -=-=-=-=-=-=-=-=-=-=-=-=

What suggestion when a school-room is not ventilated? 507. What is
said in regard to ventilating churches, concert halls, &c.? State the
illustration. 508. What remarks relative to public conveyances? 509.
State the influence of habit by Birnan.

  -=-=-=-=-=-=-=-=-=-=-=-=

510. _The sleeping-room should be so ventilated that the air in the
morning will be as pure as when retiring to rest in the evening._
Ventilation of the room would prevent morning headaches, the want of
appetite, and languor--so common among the feeble. The impure air of
sleeping-rooms probably causes more deaths than intemperance. Look
around the country, and those who are most exposed, who live in huts
but little superior to the sheds that shelter the farmer's flocks, are
found to be the most healthy and robust. Headaches, liver complaints,
coughs, and a multitude of nervous affections, are almost unknown to
them; not so with those who spend their days and nights in rooms in
which the sashes of the windows are calked, or perchance doubled, to
prevent the keen but healthy air of winter from entering their
apartments. Disease and suffering are their constant companions.

  -=-=-=-=-=-=-=-=-=-=-=-=

510. What is said of the ventilation of sleeping-rooms? What would
adequate ventilation prevent? Give a common observation.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Illustration._ By many, sleeping apartments twelve feet square and
seven feet high, are considered spacious for two persons, and good
accommodations for four to lodge in. An apartment of this size
contains 1008 cubic feet of air. Allowing ten cubic feet to each
person per minute, two occupants would vitiate the air of the room in
fifty minutes, and four in twenty-five minutes. When lodging-rooms are
not ventilated, we would strongly recommend early rising.

511. _The sick-room, particularly, should be so arranged that the
impure air may escape, and pure air be constantly admitted into the
room._ It is no unusual practice in some communities, when a child or
an adult is sick of an acute disease, to prevent the ingress of pure
air, simply from the apprehension of the attendants, that the patient
will contract a cold. Again, the prevalent custom of several
individuals sitting in the sick-room, particularly when they remain
there for several hours, tends to vitiate the air, and, consequently,
to increase the suffering and danger of the sick person. In fevers or
inflammatory diseases of any kind, let the patient breathe pure air;
for the purer the blood, the greater the power of the system to remove
disease, and the less the liability to contract colds.

_Observation._ Among children, convulsions, or "fits," usually occur
when they are sleeping. In many instances, these are produced by the
impure air which is breathed. To prevent these alarming and
distressing convulsions, the sleeping-room should be ventilated, and
there should be no curtains around the bed, or coverings over the
face, as they produce an effect similar to that experienced when
sleeping in a small, unventilated room. To relieve a child when
convulsed, carry it into the open air.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is said of the size of sleeping-rooms? 511. What is said of the
sick-room? Mention some prevailing customs in reference to these
rooms. What is said of convulsions among children?

  -=-=-=-=-=-=-=-=-=-=-=-=

512. _While occupying a room, we are insensible of the gradual
vitiation of the air._ This is the result of the diminished
sensibility of the nervous system, and gradual adaptation of the
organs to blood of a less stimulating character. This condition is
well illustrated in the hibernating animals. We are insensible of the
impure air of unventilated sleeping-rooms, until we leave them for a
walk or ride. If they have been closed, we are made sensible of the
character of the air as soon as we reënter them, for the system has
regained its usual sensibility while inhaling a purer atmosphere.

513. _In the construction of every inhabited room, there should be
adequate means of ventilation, as well as warming._ No room is well
ventilated, unless as much pure air is brought into it as the
occupants vitiate at every respiration. This can be effected by making
an aperture in the ceiling of the room, or by constructing a
ventilating flue in the chimney. This should be in contact with the
flues for the escape of smoke, but separated from them by a thin brick
partition. The hot air in the smoke flues will warm the separating
brick partition, and consequently rarefy the air in the ventilating
flue. Communication from every room in a house should be had to such
flues. The draught of air can be regulated by well-adjusted registers,
which in large rooms should be placed near the floor as well as near
the ceiling.

514. While provision is made for the escape of rarefied impure air, we
should also provide means by which pure air may be constantly admitted
into the room, as the crevices of the doors and windows are not always
sufficient; and, if they should be adequate, air can be introduced in
a more convenient, economical, and appropriate manner. There should be
an aperture opposite the ventilating flue, at or near the floor, to
connect with the outer walls of the building or external air. But if
pure heated air is introduced into the room, it obviates the necessity
of the introduction of the external air.[16]

  [16] Mr. Frederick Emerson, of Boston, has devised a simple and
       effective apparatus for removing vitiated air from a room. It
       is successfully used upon all the public school-houses of
       Boston. It is now being generally applied to the school-houses
       and other public buildings, as well as private dwellings, of
       New England.

  -=-=-=-=-=-=-=-=-=-=-=-=

512. Why are we insensible to the gradual vitiation of the air of an
unventilated room? 513. What is very important in the building of
every inhabited room? How can a room be well ventilated? 514. What is
said relative to a communication with the external air?

  -=-=-=-=-=-=-=-=-=-=-=-=

515. In warming rooms, the hot air furnaces, or box and air-tight
stoves converted into hot air furnaces, should be used in preference
to the ordinary stoves. The air thus introduced into the room is pure
as well as warm. In the adaptation of furnaces to dwelling-houses,
&c., it is necessary that the air should pass over an ample surface of
iron moderately heated; as a red heat abstracts the oxygen from the
contiguous air, and thus renders it unfit to be respired.[17]

  [17] Dr. Wyman's valuable work on "Ventilation," and the work of Henry
       Barnard, Esq., on "School-house architecture," can be
       advantageously consulted, as they give the practical methods of
       ventilating and warming shops, school-rooms, dwelling-houses,
       public halls, &c.

_Observation_. Domestic animals need a supply of pure air as well as
man. The cows of cities, that breathe a vitiated air, have, very
generally, tubercles. Sheep that are shut in a confined air, die of a
disease called the "rot," which is of a tuberculous character.
Interest and humanity require that the buildings for animals be
properly ventilated.

  -=-=-=-=-=-=-=-=-=-=-=-=

515. How should rooms be warmed? What is necessary in the adaptation
of furnaces to dwelling-houses?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXVI.

HYGIENE OF THE RESPIRATORY ORGANS, CONTINUED.


516. The change that is effected in the blood while passing through
the lungs, not only depends upon the purity of the air, but the amount
inspired. The quantity varies according to the size of the chest, and
the movement of the ribs and diaphragm.

517. _The size of the chest and lungs can be reduced by moderate and
continued pressure._ This is most easily done in infancy, when the
cartilages and ribs are very pliant; yet it can be effected at more
advanced periods of life, even after the chest is fully developed. For
want of knowledge of the pliant character of the cartilages and ribs
in infants, too many mothers, unintentionally, contract their chests,
and thus sow the seeds of disease by the close dressing of their
offspring.

518. If slight but steady pressure be continued from day to day and
from week to week, the ribs will continue to yield more and more, and
after the expiration of a few months, the chest will become diminished
in size. This will be effected without any suffering of a marked
character; but the general health and strength will be impaired. It is
not the violent and ephemeral pressure, but the moderate and
protracted, that produces the miscalled, "genteel," contracted
chests.

519. The style of dress which at the present day is almost universal,
is a prolific cause of this deformity. These baneful fashions are
copied from the periodicals, so widely circulated, containing a
"fashion plate of the latest fashions, from Paris." In every instance;
the contracted, deformed, and, as it is called, lady-like waist, is
portrayed in all its fascinating loveliness. These periodicals are
found on almost every centre-table, and exercise an influence almost
omnipotent. If the plates which corrupt the morals are excluded by
civil legislation, with the same propriety ought not those to be
suppressed that have a tendency so adverse to health?

  -=-=-=-=-=-=-=-=-=-=-=-=

516. What varies the amount of air received into the lungs? 517. How
can the size of the chest be diminished? When is this most easily
effected? 518. How are the miscalled, "genteel," contracted chests
usually produced? 519. What is said of the style of the dress at the
present day?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 100. A correct outline of the Venus de Medici, the
beau ideal of female symmetry.]

[Illustration: Fig. 101. An outline of a well-corseted modern beauty.

One has an artificial, insect waist; the other, a natural
waist. One has sloping shoulders, while the shoulders of the other are
comparatively elevated, square, and angular. The proportion of the
corseted female below the waist, is also a departure from the symmetry of
nature.]

_Observations._ 1st. The Chinese, by compressing the feet of female
children, prevent their growth; so that the foot of a _Chinese belle_
is not larger than the foot of an American girl of five years.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does fig. 100 represent? Fig. 101? Give observation 1st.

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. The American women _compress their chests_, to prevent their
growth; so that the chest of an _American belle_ is not larger than
the chest of a Chinese girl of five years. Which country, in this
respect, exhibits the greater intelligence?

3d. The chest can be deformed by making the linings of the waists of
the dresses tight, as well as by corsets. Tight vests, upon the same
principle, are also injurious.

520. In children, who have never worn close garments, the circumference
of the chest is generally about equal to that of the body at the hips;
and similar proportions would exist through life, if there were no
improper pressure of the clothing. This is true of the laboring
women of the Emerald Isle, and other countries of Europe, and in the
Indian female, whose blanket allows the free expansion of the chest. The
symmetrical statues of ancient sculptors bear little resemblance to
the "beau ideal" of American notions of elegant form. This perverted
taste is in opposition to the laws of nature. The design of the human
chest is not simply to connect the upper and lower portions of the
body, like some insects, but to form a case for the protection of the
vital organs.

521. _Individuals may have small chests from birth._ This, to the
particular individual, is natural; yet it is adverse to the great and
general law of Nature relative to the size of the human chest. Like
produces like, is a general law of the animal and vegetable kingdoms.
No fact is better established, than that which proves the hereditary
transmission from parents to children of a constitutional liability
to disease and the same may be said in regard to their conformations.
If the mother has a small, taper waist, either hereditary or acquired,
this form may be impressed on her offspring;--thus illustrating the
truthfulness of scripture, "that the sins of the parents shall be
visited upon the children unto the third and fourth generation."

  -=-=-=-=-=-=-=-=-=-=-=-=

Observation 2d. Observation 3d. 520. What is the size of the chest of
a child that has always worn loose clothing? What is said of the size
of the laboring women of Ireland, and the Indian female? How is it in
ancient statues? What is the design of the chest? 521. What is a
general law of both the animal and vegetable kingdoms? What fact in
this connection is well established?

  -=-=-=-=-=-=-=-=-=-=-=-=

522. _The quantity of air inhaled is modified by the capacity of the
respiratory organs._ The necessity of voluminous lungs may he
elucidated by the following experiment: Suppose a gill of alcohol,
mixed with a gill of water, be put into a vessel having a square foot
of surface, and over the vessel a membrane be tied, and that the water
will evaporate in twenty-four hours. If the surface had been only six
inches square, only one fourth of the water would have evaporated
through the membrane in the given time. If the surface had been
extended to two square feet, the water would have evaporated in twelve
hours.

523. Apply this principle to the lungs: suppose there are two hundred
feet of carbonic acid to be carried out of the system every
twenty-four hours. This gas, in that time, will pass through a
vesicular membrane of two thousand square feet. If the lungs were
diminished in size, so that there would be only one thousand square
feet of vesicular membrane, the amount of carbonic acid would not, and
could not, be eliminated from the system. Under such circumstances,
the blood would not be purified.

524. Again; suppose the two thousand square feet of membrane would
transmit two hundred cubic feet of oxygen into the system every
twenty-four hours. If it should be diminished one half, this amount of
oxygen would not pass into the blood. From the above illustrations we
may learn the importance of well-developed chests and voluminous
lungs; for, by increasing the size of the lungs, the oxygen is more
abundantly supplied to the blood, and this fluid is more perfectly
deprived of its carbon and hydrogen.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does this hereditary transmission prove? 522. How is the
necessity of voluminous lungs illustrated? 525. How is this principle
applied to the interchange of products in the lungs?

  -=-=-=-=-=-=-=-=-=-=-=-=

525. The chest is not only most expanded at its lower part, but the
portion of the lungs that occupies this space of the thoracic cavity
contains the greater part of the air-cells; and, from the lower two
thirds of the lungs the greatest amount of carbonic acid is abstracted
from the blood, and the greatest amount of oxygen gas is conveyed into
the circulating fluid. Hence, contracting the lower ribs is far more
injurious to the health than diminishing the size of the upper part of
the chest.

526. The question is often asked, Can the size of the chest and the
volume of the lungs be increased, when they have been injudiciously
compressed, or have inherited this unnatural form? The answer is in
the affirmative. The means for attaining this end are, a judicious
exercise of the lungs, by walking in the open air, reading aloud,
singing, sitting erect, and fully inflating the lungs at each act of
inspiration. If the exercise be properly managed and persevered in, it
will expand the chest, and give tone and health to the important
organs contained in it. But, if the exercise be ill-timed or carried
to excess, the beneficial results sought will probably not be
attained.

_Observation._ Scholars, and persons who sit much of the time, should
frequently, during the day, breathe full and deep, so that the
smallest air-cells may be fully filled with air. While exercising the
lungs, the shoulders should be thrown back and the head held erect.

527. _The movement of the ribs and diaphragm is modified by the
dress._ When the lungs are properly filled with air, the chest is
enlarged in every direction. If any article of apparel is worn so
tight as to prevent the full expansion of the chest and abdomen, the
lungs, in consequence, do not receive air sufficient to purify the
blood. The effect of firm, unyielding clothing, when worn tight, in
preventing a due supply of air to the lungs, may be shown by the
following illustration.

  -=-=-=-=-=-=-=-=-=-=-=-=

525. Why is it more injurious to contract the lower part of the chest
than the upper? 526. How can the size of the chest be increased when
it is contracted? Give the observation. 527. How is the movement of
the ribs and diaphragm modified?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Illustration._ If the diameter of a circle is three feet, the
circumference will be nine feet. If the diameter is extended to four
feet, the circumference will be increased to twelve feet. Should a
tight band be thrown around a circle of nine feet, its diameter cannot
be increased, for the circumference cannot be enlarged.

528. Any inelastic band, drawn closely around the lower part of the
chest, or the abdomen, below the ribs, operates like the band in the
preceding illustration, in restricting the movement of the ribs. When
any article of dress encircles either the chest or abdomen, so as to
prevent an increase of its circumference, it has an injudicious
tendency, as it prevents the introduction of air in sufficient
quantities to purify the blood. The question is not, How much
restriction of the respiratory movements can be endured, and life
continue? but, Does any part of the apparel restrict the movements? If
it does, it is a violation of the organic laws; and though Nature is
profuse in her expenditures, yet sooner or later, she sums up her
account.

529. In determining whether the apparel is worn too tight, inflate the
lungs, and, if no pressure is felt, no injurious effects need be
apprehended from this cause. In testing the tightness of the dress,
some persons will contract to the utmost the abdominal muscles, and
thus diminish the size of the chest, by depressing the ribs; when
this is done, the individual exclaims, "How loose my dress is!" This
practice is both deceptive and ludicrous. A good test is, to put the
hand on the chest below the arm; if there is no movement of the ribs
during respiration, the apparel is too tight. The only reliable test,
however, is a full inflation of the lungs.

  -=-=-=-=-=-=-=-=-=-=-=-=

How is the effect of unyielding clothing, when worn tight, illustrated?
528. What effect has an inelastic band upon the lower part of the
chest? What question is asked? 529. How can we determine whether the
apparel is worn too tight?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Many individuals do not realize the small amount of
force that will prevent the enlargement of the chest. This can be
demonstrated by drawing a piece of tape tightly around the lower part
of the chest of a vigorous adult, and confining it with the thumb and
finger. Then endeavor fully to inflate the lungs, and the movement of
the ribs will be much restricted.

530. _The position in standing and sitting influences the movement of
the ribs and diaphragm._ When the shoulders are thrown back, and when
a person stands or sits erect, the diaphragm and ribs have more
freedom of motion, and the abdominal muscles act more efficiently;
thus the lungs have broader range of movement than when the shoulders
incline forward, and the body is stooping.

531. _Habit exercises an influence upon the range of the respiratory
movements._ A person who has been habituated to dress loosely, and
whose inspirations are full and free, suffers more from the tightness
of a vest or waistband, than one, the range of movements of whose
chest has long been subjected to tight lacing.

532. _The condition of the brain exercises a great influence upon
respiration._ If the brain is diseased, or the mind depressed by
grief, tormented by anxiety, or absorbed by abstract thought, the
contractile energy of the diaphragm and muscles that elevate the
ribs, is much diminished, and the lungs are not so fully inflated, as
when the mind is influenced by joy or other exhilarating emotions. The
depressing passions likewise lessen the frequency of respiration. By
the influence of these causes, the blood is but partially purified,
and the whole system becomes enfeebled. Here we may see the admirable
harmony between the different parts of the body, and the adaptation of
all the functions to each other.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give another test. How can the amount of pressure necessary to prevent
the enlargement of the chest be demonstrated? 530. Show the effect of
position on the movements of the ribs and diaphragm. 531. Show the
effect of habit on the respiratory movements. 532. State the influence
of the mind upon respiration.

  -=-=-=-=-=-=-=-=-=-=-=-=

533. As the quantity of air inhaled at each unimpeded inspiration in
lungs of ample size, is about forty cubic inches, it follows, if the
movement of the ribs and diaphragm is restricted by an enfeebled
action of the respiratory muscles, or by any other means, the blood
will not be perfectly purified. In the experiment, (§ 522, 523,)
suppose forty cubic inches of air must pass over the membrane twenty
times every minute, and that this is the amount required to remove the
vapor which arises from the membrane; if only half of this amount of
air be supplied each minute, only one half as much water will be
removed from the alcohol through the membrane in twenty-four hours;
consequently, the alcohol would be impure from the water not being
entirely removed.

534. Restrain the elevation of the ribs and depression of the
diaphragm, so that the quantity of air conveyed into the lungs will be
reduced to twenty cubic inches, when forty are needed, and the results
will be as follows: Only one half of the carbonic acid will be
eliminated from the system, and the blood will receive but one half as
much oxygen as it requires. This fluid will then be imperfectly
oxydated, and partially freed of its impurities. The impure blood will
be returned to the left side of the heart, and the whole system will
suffer from an infringement of organic laws.

  -=-=-=-=-=-=-=-=-=-=-=-=

533. Illustrate the effect upon the blood when the respiratory muscles
are enfeebled in their action. 534. Show how the blood is imperfectly
purified by restricting the movements of the ribs and diaphragm.

  -=-=-=-=-=-=-=-=-=-=-=-=

535. _Scrofula, or consumption, frequently succeeds a depressed state
of the nervous system._ These diseases arise from the deposition of
tuberculous matter in different parts of the body. Those individuals
who have met with reverses of fortune, in which character and property
were lost, afford painful examples. Hundreds yearly die from the
effect of depressed spirits, caused by disappointed hopes, or
disappointed ambition.

_Illustration._ A striking instance of the effects of mental
depression is related by Lænnec. In a female religious establishment
in France, great austerities were practised; the mind was absorbed in
contemplating the terrible truths of religion, and in mortifying the
flesh. The whole establishment, in the space of ten years, was
several times depopulated--with the exception of the persons
employed at the gate, in the kitchen, and garden--with that fatal
disease, consumption. This institution did not long continue, but
was suppressed by order of the French government.

536. _The purity of the blood is influenced by the condition of the
lungs._ When the bronchial tubes and air-cells have become partially
impervious to air, from pressure upon the lungs, from fluids in the
chest, from tumors, or from the consolidation of the cells and tubes
from disease,--as inflammation, or the deposition of yellow, cheesy
matter, called tubercles,--the blood will not be purified, even if the
air is pure, the lungs voluminous, and the respiratory movements
unrestricted, as the air cannot permeate the air-cells.

_Observations._ 1st. The twenty-three who escaped immediate death in
the Black Hole of Calcutta were soon attacked with inflammation of the
lungs, by which these organs were consolidated, and thus prevented
the permeation of air into their cells. This disease of the lungs was
caused by breathing vitiated air.

  -=-=-=-=-=-=-=-=-=-=-=-=

535. Mention some of the effects of mental depression upon the body.
What is related by Lænnec? 536. Does the condition of the lungs
influence the purity of the blood? Mention some of the conditions that
will impede the oxydation of blood in the lungs. What occurred to
those persons who escaped death in the Black Hole of Calcutta?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. One of the precursory symptoms of consumption is the feeble murmur
of respiration in the upper part of the lungs. This condition of these
organs is produced by, or frequently follows, mental depression, the
breathing of impure air, the stooping position in standing or sitting,
and the restriction of the movements of the ribs and diaphragm.

3d. Persons asphyxiated by carbonic acid, water, strangling, or any
noxious air, after resuscitation, are usually affected with coughs and
other diseases of the lungs.

537. COLDS and COUGHS are generally induced by a chill, that produces
a contraction of the blood-vessels of the skin; and the waste
material, which should be carried from the body by the agency of the
vessels of this membrane, is retained in the system, and a great
portion of it is returned to the mucous membrane of the lungs. For
such is the harmony established by the Creator, that if the function
of any portion of the body is deranged, those organs whose offices are
similar take on an increased action.

538. The waste material, that should have passed through the many
outlets of the skin, creates an unusual fulness of the minute vessels
that nourish the mucous membrane of the bronchia; this induces an
irritation of these vessels, which increases the flow of blood to the
nutrient arteries of the lungs. There is, also, a thickening of the
lining membrane of the lungs, caused by the repletion of the bronchial
vessels of the mucous membrane; this impedes the passage of air
through the small bronchial tubes, and consequently the air-vesicles
cannot impart a sufficient quantity of oxygen to purify the blood, and
this fluid, imperfectly purified, does not pass with facility through
the lungs. An additional obstacle to the free passage of air into the
lungs, is the accumulation of blood in the pulmonary vessels.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is one of the precursory symptoms of consumption? How is this
condition frequently produced? What diseases usually follow asphyxia
by carbonic acid, water, strangling, &c.? 537. How are colds generally
induced? 538. What effect has a common cold upon the mucous membrane
of the lungs?

  -=-=-=-=-=-=-=-=-=-=-=-=

539. As colds and coughs are very generally treated by the "matrons"
of the community, or by the patient, the following suggestions may aid
in directing a proper treatment: To effect a speedy cure, it is
necessary to diminish the amount of fluid in the vessels of the lungs.
This can be effected in two ways: 1st. By diminishing the quantity of
blood in the system; 2d. By diverting it from the lungs to the skin.
The first condition can be easily and safely affected, by abstaining
from food, and drinking no more than a gill of fluid in twenty-four
hours. As there is a continuous waste from the skin and other organs
of the system, the quantity of blood by this procedure will be
diminished, and the lungs relieved of the accumulated fluid.

540. The second condition can be accomplished by resorting to the warm
or vapor bath. These and the common sweats will invite the blood from
the lungs to the skin. By keeping up the action of the skin for a few
hours, the lungs will be relieved. In some instances, emetics and
cathartics are necessary; mucilages, as gum arabic or slippery-elm
bark, would be good. After the system is relieved, the skin is more
impressible to cold, and consequently requires careful protection by
clothing. In good constitutions, the first method is preferable, and
generally sufficient without any medicine or "sweating."

541. _The method of resuscitating persons apparently drowned._ In the
first instance, it is necessary to press the chest, suddenly and
forcibly, downward and backward, and instantly discontinue the
pressure. Repeat this without intermission, until a pair of bellows
can be procured. When the bellows are obtained, introduce the nozzle
well upon the base of the tongue, and surround the mouth and nose with
a towel or handkerchief, to close them. Let another person press upon
the projecting part of the neck, called "Adam's apple," while air is
introduced into the lungs through the bellows. Then press upon the
chest, to force the air from the lungs, to imitate natural breathing.
(Appendix M.)

  -=-=-=-=-=-=-=-=-=-=-=-=

539. Give the first method for the treatment of cold. 540. The second
method. 541, 542. How should persons apparently drowned be treated?

  -=-=-=-=-=-=-=-=-=-=-=-=

542. Continue the use of the bellows, and forcing the air out of the
chest, for an hour at least, unless signs of natural breathing come
on. Wrap the body in warm, dry blankets, and place it near the fire,
to preserve the natural warmth, as well as to impart artificial heat.
Every thing, however, is secondary to filling the lungs with air.
Avoid all friction until breathing is restored. Send immediately for
medical aid.

543. _The means of resuscitating persons asphyxiated from electricity,
&c._ In apparent death from electricity, (lightning,) the person is
frequently asphyxiated from _pa-ral´y-sis_ (palsy) of the respiratory
muscles. To recover such persons, resort to artificial respiration. In
cases of apparent death from hanging or strangling, the knot should be
untied or cut immediately; then use artificial respiration, or
breathing, as directed in apparent death from drowning.

_Observation._ It is an impression, in many sections of the country,
that the law will not allow the removal of the cord from the neck of a
body found suspended, unless the coroner be present. It is therefore
proper to say, that no such delay is necessary, and that no time
should be lost in attempting to resuscitate the strangled person.

544. _The method of resuscitating persons apparently dead from
inhaling carbonic acid gas._ When life is apparently extinct from
breathing carbonic acid gas, the person should be carried into the
open air. The head and shoulders should be slightly elevated; the face
and chest should be sponged or sprinkled with cold water, or cold
vinegar and water, while the limbs are wrapped in dry, warm blankets.
In this, as in asphyxia from other causes, immediately resort to
artificial respiration.

  -=-=-=-=-=-=-=-=-=-=-=-=

543. What treatment should be adopted in asphyxia from electricity?
From hanging? 544. What should be the treatment in asphyxia from
inhaling carbonic acid gas?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observations._ 1st. Many persons have died from breathing carbonic
acid that was formed by burning charcoal in an open pan or portable
furnace, for the purpose of warming their, sleeping-rooms. This is not
only produced by burning charcoal, but is evolved from the live coals
of a wood fire; and being heavier than air, it settles on the floor of
the room; and, if there is no open door or chimney-draught, it will
accumulate, and, rising above the head of an individual, will cause
asphyxia or death.

2d. In resuscitating persons apparently dead from causes already
mentioned, if a pair of bellows cannot be procured immediately, let
their lungs be inflated by air expelled from the lungs of some person
present. To have the expired air as pure as possible, the person
should quickly inflate his lungs, and instantly expel the air into
those of the asphyxiated person. _Place the patient in pure air, admit
attendants only into the apartment, and send for a physician without
delay._

  -=-=-=-=-=-=-=-=-=-=-=-=

What sad results frequently follow the burning of charcoal in a closed
room? What suggestion in resuscitating asphyxiated persons?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXVII.

ANIMAL HEAT.


545. The true sources of animal heat, or calorification, are still
imperfectly known. No hypothesis has, as yet, received the concurrent
assent of physiologists. We see certain phenomena, but the ultimate
causes are hidden from our view. Its regular production, to a certain
degree, is essential both to animal and vegetable life.

546. There is a tendency between bodies of different temperature to an
equilibrium of heat. Thus, if we touch or approach a hot body, the
heat, or caloric passes from that body to our organs of feeling, and
gives the sensation of heat. On the contrary, when we touch a cold
body, the heat passes from the hand to that body, and causes a
sensation of cold.

547. The greater number of animals appear cold when we touch them;
and, indeed, the temperature of their bodies is not much above that of
the atmosphere, and changes with it. In man, and other animals that
approach him in their organization, it is otherwise. They have the
faculty of producing a sufficient quantity of caloric to maintain
their temperatures nearly at the same degree, under all atmospheric
changes, and keep themselves warm.

548. Those animals whose proper heat is not very perceivable, are
called _cold_-blooded; as most species of fishes, toads, snakes,
turtles, and reptiles generally. Those animals which produce
sufficient heat independently of the atmosphere surrounding them, are
called _warm_-blooded; as man, birds, quadrupeds, &c.

  -=-=-=-=-=-=-=-=-=-=-=-=

545-570. _What is said respecting animal heat?_ 545. Are the true
sources of animal heat known? What do we see? 546. What is the tendency
between bodies of different temperatures? Give an explanation. 547.
What is said of the temperature of animals? 548. What is meant by
cold-blooded animals? By warm-blooded animals?

  -=-=-=-=-=-=-=-=-=-=-=-=

549. The temperature of man is about 98°, (Fahrenheit's thermometer,)
and that of some other animals is higher; the temperature of birds,
for example, is about 110°. It is obvious, that in most parts of the
globe, the heat of the atmosphere is, even in summer, less than that
of the human body. In our latitude, the mercury rarely attains 98°,
and sometimes it descends to several degrees below zero.

550. Captain Parry, with his ship's company, in his voyage of
discovery to the arctic regions, wintered in a climate where the
mercury was at 40°, and sometimes at 55° below zero. Captain Back
found it 70° below zero. These were 72° and 102° below the freezing
point, or about 200° below that of their own bodies, and still
they were able to resist this low temperature, and escape being
"frost-bitten."

551. Captain Lyon, who accompanied Captain Parry in his second voyage
to the northern regions, found the temperature of an arctic fox to be
106°, while that of the atmosphere was 32° below zero; making a
difference between the temperature of the fox and that of the
atmosphere, of 138°. Captain Scoresby found the temperature of a
whale, in the Arctic Ocean, to be 104°, or nearly as high as that of
other animals of the same kind in the region of the equator, while the
temperature of the ice was as low as 32°, and the water was nearly as
cold. These facts show what a strong counteracting energy there is in
animals against the effects of cold.

552. On the other hand, it has been ascertained by numerous and
well-conducted experiments, that the human body can be exposed, even
for a length of time, to a very high temperature, without essentially
elevating that of the body. Chantrey, the sculptor, often entered the
furnace, heated for drying his moulds, when the temperature indicated
by the thermometer was 330°. Chaubert, the Fire-King, is said to have
entered ovens when heated to 600°. In 1774, Sir Charles Blagden
entered a room in which the mercury rose to 260°. He remained eight
minutes without suffering.

  -=-=-=-=-=-=-=-=-=-=-=-=

549. What is the temperature of the human body? Of birds? How does the
heat of the atmosphere in summer, in our latitude, compare with that
of the human system? 550. What is related of Captain Parry? Of Captain
Back? 551. Of Captain Lyon? Of Captain Scoresby? What do these facts
show? 552. What has been ascertained on the other hand?

  -=-=-=-=-=-=-=-=-=-=-=-=

553. In order to render it certain that there was no fallacy, says Sir
Charles Blagden, "in the degree of heat shown by the thermometer, but
that the air breathed was capable of producing all the well-known
effects of such a heat on inanimate matter, I put some eggs and
beefsteak upon a tin frame placed near the thermometer, and farther
distant from the cockle than from the wall of the room. In about
twenty minutes the eggs were taken out, roasted quite hard; and in
forty-seven minutes, the steak was not only dressed, but almost dry."

554. If a thermometer be placed under the tongue of a healthy person,
in all climates and seasons the temperature will be found nearly the
same. Sir Charles Blagden, "while in the heated room, breathed on a
thermometer, and the mercury sank several degrees; and when he expired
forcibly, the air felt cool as it passed through the nostrils, though
it was scorching hot when it entered them in inspiration."

_Observation._ Did not the human body possess within itself the power
of generating and removing heat, so as to maintain nearly an equality
of temperature, the most fatal consequences would ensue. In northern
latitudes, especially, in severe weather of winter, the blood would be
converted into a solid mass, and on the other hand, the fatty
secretion, when subjected to equatorial heat, would become fluid, and
life would be extinguished.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is related of Chantrey? Of Chaubert? Of Sir Charles Blagden? 553.
Give Sir Charles's own statement. 554. What is said of the temperature
of the human tongue? Mention the experiment by Sir Charles Blagden.
What would be the effect if the human system did not maintain an
equality of temperature?

  -=-=-=-=-=-=-=-=-=-=-=-=

555. To enable man, and other warm-blooded animals, to maintain this
equilibrium of temperature under such extremes of heat and cold,
naturally suggests two inquiries: 1st. By what organs is animal heat
generated? 2d. By what means is its uniformity maintained?

556. The ancients had no well-arranged theory on the subject of animal
heat. They believed that the chief object of respiration was to cool
the blood, and that the heart was the great furnace where all the heat
was generated. At a later period, Mayow, from his discoveries
respecting respiration, asserted that the object of respiration was to
produce heat, and denied that the blood was cooled in the lungs.

557. When it was discovered that, both in combustion and respiration,
carbonic acid was produced and oxygen absorbed, it led Dr. Black to
conclude that breathing was a kind of combustion by which all the heat
of the body was produced. This theory was objected to, because, if all
the heat was generated in the lungs, like those parts of a stove in
contact with the fuel, they would be at a higher temperature than
those parts at a distance, which was known not to exist.

558. The next theory, and one which received the sanction of the
scientific men of Europe, was proposed by Dr. Crawford. He agreed with
Dr. Black that heat not only was generated in the lungs, but that the
arterial blood had a greater capacity for heat than the venous, and
that this increase of capacity takes place in the lungs. At the moment
heat is generated, a portion of it, under the name of latent heat, is
absorbed and conveyed to the different parts of the body Wherever
arterial blood is converted into venous, this latent heat is given
out. But, unfortunately for this theory, Dr. Davy proved the capacity
of both, for heat, to be nearly the same.

  -=-=-=-=-=-=-=-=-=-=-=-=

555. What inquiries are naturally suggested? 556. What was the theory
of the ancients? What did Mayow assert at a later period? 557. What
was the theory of Dr. Black? The objection? 558. What was the theory
of Dr Crawford?

  -=-=-=-=-=-=-=-=-=-=-=-=

559. No one can doubt that respiration and animal heat are closely
connected. Those animals whose respiratory apparatus is the most
extended, have the highest temperature. An example is seen in birds,
whose organs of respiration extend over a large part of the body, and
their temperature is 12° above man; while the respiratory apparatus of
cold-blooded animals, as some kinds of fish, is imperfect, and only a
small quantity of blood is subjected, at any time, to the effects of
respiration.

560. To understand the process by which heat is generated in the human
system and in animals, it will be necessary to state: 1st. That the
apparent heat of a body, as perceived by the touch, or as indicated by
a thermometer, is not the measurement of heat contained in the body,
or its capacity for heat.

_Illustration._ If we mix one pound of water, at the temperature of
60°, with another pound at 91°, the resulting temperature will be
exactly the medium, or 75½°. But, if we mix a pound of water at 60°
with a pound of quicksilver at 91°, the resulting temperature will be
only 61°, because the capacity of water for heat is so much greater
than that of quicksilver, that the heat which raised the quicksilver
31° will raise the water only 1°.

561. 2d. When the density and the arrangement of the atoms of a body
are changed, its capacity to hold heat in a latent state is altered.
If it will retain more, heat will be absorbed from contiguous and
surrounding substances; but, if its capacity for caloric is lessened,
heat will be set free and given out to surrounding bodies.

  -=-=-=-=-=-=-=-=-=-=-=-=

The objection? 559. In what do all the physiologists of the present
day concur? How is it proved that respiration and animal heat are
closely connected? 560. What is said of the apparent heat of bodies?
How is this illustrated? 561. What is the effect when the density and
the arrangement of the atoms of a body are changed?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Illustrations._ 1st. Ice and salt, (Chl. of Sodium,) when mixed, are
converted into a fluid. In this state they will hold more heat than
when solid. The heat necessary to produce this change is drawn from
the surrounding medium, which is made proportionally colder by the
loss of caloric imparted to the ice and salt. It is by this chemical
process that "ice-cream" is made.

2d. On the other hand, mix water and sulphuric acid, (oil of vitriol,)
of the temperature of 60°, and the mixture will become quite warm, and
will freely impart its heat to surrounding and contiguous objects.

562. The same principle is exhibited, when oxygen unites with an
inflammable body, as in the burning of wood, coal, oil, &c. In
combustion, the oxygen of the atmosphere unites with carbon and
hydrogen, and carbonic acid and water are produced. This process,
according to all the known laws of caloric, is attended with heat. The
quantity of heat disengaged in combustion is always in proportion to
the amount of carbon and hydrogen consumed; thus a piece of wood
weighing one pound, in burning slowly, would give out the same
quantity of heat as a pound of shavings of the same wood, in burning
rapidly. Upon these principles, the production of animal heat may be
understood.

563. The food contains carbon and hydrogen. These exist in the chyle.
The old and waste atoms of the body likewise contain the same
elements. In the lungs the oxygen and nitrogen of the inspired air are
separated. It is now supposed that the oxygen enters the capillary
vessels of the lungs, and mingles with the blood, with which it is
carried to the heart and thence to the nutrient capillary vessels of
every part of the system.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give the 1st illustration. The 2d. 562. What changes take place when
oxygen unites with an inflammable body? To what is the quantity of
heat proportionate in combustion? Give an example. 563. How are carbon
and hydrogen supplied to the system? How the oxygen? Where does the
oxygen mingle with the blood?

  -=-=-=-=-=-=-=-=-=-=-=-=

564. In the capillary vessels, the oxygen of the arterial blood unites
with the carbon and hydrogen which the refuse materials contain, and
carbonic acid and water are formed. The combustion of carbon and
hydrogen in the capillaries of every part of the system, (the lungs
not excepted,) is attended with a disengagement of heat, and the
carbonic acid and water are returned to the lungs in the dark-colored
blood, and evolved from the system.

565. Sir Benjamin Brodie and some others have maintained, that the
heat of the system is generated exclusively by the influence of the
brain and nerves. This theory is discarded by most physiologists; yet
it is true that the nervous system exercises a great influence over
the action of the capillary vessels in the process of nutrition,
secretion, and absorption. When these operations are most active, the
change among the particles of matter of which the body is composed, is
then greatest, and the generation of heat is increased in a
corresponding degree.

566. The necessity of pure, red blood in the production of animal
heat, is shown when the vessels that carry blood to a limb are
ligated, or tied; the part immediately becomes colder. The necessity
of nervous influence is seen in the diminished temperature of a
paralytic limb.

567. Our next inquiry is, By what means is the uniformity of
temperature in the body maintained? As there is a constant generation
of heat in the system, there would be an undue accumulation,--so much
so as to cause disagreeable sensations,--if there were no means by
which it could be evolved from the body, or its production lessened.

  -=-=-=-=-=-=-=-=-=-=-=-=

564. Where does it unite with the carbon and hydrogen contained in the
body, and how is heat generated? 565. What was the theory of Sir
Benjamin Brodie? Is this theory in general discarded? What is true of
this theory? 566. How is the necessity of pure, red blood and nervous
action shown in the production of animal heat?

  -=-=-=-=-=-=-=-=-=-=-=-=

568. It has been ascertained that the principal means by which the
system is kept at a uniform temperature, is the immense evaporation
from the skin and lungs. These membranes, in an ordinary state, are
constantly giving out water, which is converted into vapor, and
carried off by the surrounding air. The quantity of heat abstracted
from the system to effect this, depends on the rapidity of the change
of air, its temperature, and the amount of water it contains in a
state of vapor. The quantity removed is greatest when the air is warm
and dry, and the change, or current, rapid.

_Observations._ 1st. The first discovery of the use of free
evaporation of the perspiration from the skin in reducing the heat of
the body, and the analogy subsisting between this process and that of
the evaporation of water from a rough porous surface, so constantly
resorted to in warm countries, as an efficacious means of reducing the
temperature of the air in rooms, and of wine and other drinks, much
below that of the surrounding atmosphere, was made by Franklin.

2d. In all ages and climes, it has been observed that the increased
temperature of the skin and system in fevers, is abated as soon as
free perspiration is restored. In damp, close weather, as during the
sultry days of August, although the temperature is lower, we feel a
disagreeable sensation of heat, because the saturation of the air with
moisture lessens evaporation, and thus prevents the escape of heat
through the lungs and skin.

3d. It is on the principle of the evaporation of fluids that warm
vinegar and water, applied to the burning, aching head, cools it, and
imparts to it a comfortable feeling. The same results follow if warm
liquids are applied to the skin in the hot stage of fever; and this
evaporation can be increased by constant fanning.

  -=-=-=-=-=-=-=-=-=-=-=-=

568. What are the principal means by which a uniform temperature of
the body is maintained? On what does the quantity of heat abstracted
from the system depend? What discovery relative to animal heat is due
to Franklin? What is said of free perspiration in fevers? What
occasions the disagreeable sensation of heat in damp, close weather?

  -=-=-=-=-=-=-=-=-=-=-=-=

4th. It is frequently noticed, in very warm weather, that dogs and
other domestic animals are seen with their tongues out of their
mouths, and covered with frothy secretions. This is merely another
mode of reducing animal heat, as the skin of such animals does not
perspire as much as that of man.

569. Under some circumstances, a portion of the heat of the system is
removed by radiation. When cold air comes in contact with the skin and
mucous membrane of the lungs, heat is removed from the body, as from a
stove, to restore an equilibrium of temperature. The removal of heat
from the body is greatest when we are in a current of cold air, or
when a brisk, cold wind is blowing upon us.

570. As the primary object of the different processes of nutrition is
to supply animal heat, so the action of the different nutritive organs
is modified by the demands of the system for heat. When heat is
rapidly removed from the body, the functional activity of the organs
of nutrition is increased. When the system is warmed by foreign
influence, the activity of the nutritive organs is diminished. This
leads to the natural, and, we may add, instinctive change in the
quality and quantity of food at different seasons of the year.

  -=-=-=-=-=-=-=-=-=-=-=-=

569. When is heat radiated from the body? When is it greatest? 570.
What is the primary object of the different processes of nutrition?
When is the activity of the nutritive organs increased? When
diminished? To what does this lead?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXVIII.

HYGIENE OF ANIMAL HEAT.


571. The amount of heat generated in man and inferior animals depends
upon the quantity and quality of the food, age, exercise, the amount
and character of the respired air, condition of the brain, skin, and
general system.

572. _Animal heat is modified by the proportion of digestible carbon
which the food contains, and by the quantity consumed._ As the kind of
fuel that contains the greatest amount of combustible material evolves
the most caloric when burned, so those articles of food that contain
the greatest quantity of carbon produce the most heat when converted
into blood. The inhabitants of the frigid zones, and individuals in
temperate climates during the cold season, consume with impunity
stimulating animal food, that contains a large proportion of carbon,
while the inhabitants of the tropical regions, and persons in
temperate climates during the warm season, are more healthy with a
less stimulating or vegetable diet.

_Observation._ When we ride or labor in cold weather, an adequate
amount of nutritious food will sustain the warmth of the system better
than intoxicating drinks.

573. _Age is another influence that modifies the generation of animal
heat._ The vital forces of the child being feeble, less heat is
generated in its system than in that of an adult. The experiments
of Dr. Milne Edwards show that the power of producing heat in
warm-blooded animals, is at its minimum at birth, and increases
successively to adult age; and that young children part with their
heat more readily than adults, and, instead of being warmer, are
generally a degree or two colder. After adult age, as the vital powers
decline, the generation of heat is diminished, as the energies of
the system are lessened. Hence the young child, and the debilitated
aged person, need more clothing than the vigorous individual of
middle age.

  -=-=-=-=-=-=-=-=-=-=-=-=

571-585. _Give the hygiene of animal heat._ 571. State some of the
influences that modify the generation of animal heat. 572. What
element of the food influences the generation of heat? When and
where can animal food be eaten with impunity? Give the practical
observation.

  -=-=-=-=-=-=-=-=-=-=-=-=

574. _Exercise is an influence that modifies the generation of animal
heat._ As carbon and hydrogen enter into the composition of the organs
of the body, whatever increases the flow of blood in the system,
increases also the deposition of new material, and the removal of the
waste particles. This change among the particles of matter is attended
with an elevation of temperature, from the union of oxygen with the
carbon and hydrogen of the waste atoms. For this reason, a person in
action is warmer than in a quiescent state. Consequently, the amount
of clothing should be increased, when exercise or labor is diminished
or suspended.

575. On the other hand, whatever impedes the circulation and the
interchange of the atoms of matter, diminishes animal heat. Common
observation shows, that the extremities are not as warm when tight
gloves or boots are worn as when they are loose. One reason is, the
circulation of blood is impeded, which is attended with less frequent
change of the particles of matter.

576. _The quantity of air which is inhaled modifies the heat of the
system._ In the generation of heat in a stove, air, or oxygen, is as
essential as the wood or coal. It is equally so in the production of
animal heat. The oxygen of the inspired air should be in proportion to
the carbon and hydrogen to be consumed. This requires voluminous
lungs, together with free movements of the ribs and diaphragm. A
person whose chest is small, and whose apparel is worn tight over the
ribs, suffers more from the cold, and complains more frequently of
chilliness and cold extremities, than the broad-chested and loosely
dressed.

  -=-=-=-=-=-=-=-=-=-=-=-=

What do the experiments of Dr. Milne Edwards show? 574. Why does
exercise influence animal heat? 575. What is the effect when the
circulation of blood is impeded? Give examples. 576. Why do those
persons that have broad chests and voluminous lungs suffer less from
cold than the narrow-chested with small lungs?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Fishes that breathe by means of gills, as the cod,
pike, &c., depend solely on the small quantity of oxygen that is
contained in the air mixed with the water. Their temperature is not
much greater than the medium in which they live. Whales, dolphins,
&c., breathe by means of lungs, and the inhalation of atmospheric air
makes their temperature about 100°, independent of the heat of the
element in which they live.

577. _The quality of respired air influences the generation of animal
heat._ In vestries, and other public rooms, when crowded with an
audience, where the ventilation is inadequate, the lamps will emit but
a faint light, because the oxygen is soon expended, and there is not
enough of the vivifying principle to unite with the oil and disengage
light. In the human body, when the respired air has lost some of its
life-giving properties, the combustion that takes place in different
parts of the system is not so complete as when it contains a proper
proportion of oxygen; and hence less heat is disengaged. For this
reason, those persons that breathe impure air, either in the daytime
or night, require more clothing, than those that work and sleep in
well-ventilated rooms.

578. _The condition of the brain and nervous system affects the
generation of animal heat._ If the brain is diseased, or the mind is
absorbed in thought, depressed by sorrow, or aroused from fear, the
breathing becomes slow and scarcely perceptible, and a chilliness
pervades the body, particularly the extremities; while, on the
contrary, if the mind and nervous system are excited by joyous and
agreeable emotions, the circulation of blood is quicker, and the
system more powerfully resists external cold. During sleep, when the
brain is partially inactive, less heat is generated than when awake.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is said of those fishes that breathe by means of gills? Of those
that breathe by means of lungs? 577. Why do lamps give but a faint
light in crowded, unventilated rooms? What effect on animal heat has
impure air? 578. Mention the effects of some of the mental emotions on
animal heat.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ The preceding remark explains why an individual who
sleeps in the same clothing that was adequate to prevent chills while
awake, contracts a cold, unless he throws over him an additional
covering.

579. _The state of the skin exercises much influence in the generation
of heat._ If the functions of this membrane are not interrupted, more
heat will be generated than when it is pallid and inactive. The action
of the capillaries is most energetic when the skin is clean; on this
account, before taking a walk or a ride, in cold weather, remove all
impurities from the skin, by thorough ablution and vigorous friction.

580. _The amount and kind of clothing modify the temperature of the
system._ Those persons that are well clothed have greater power to
resist cold than the thinly apparelled, because both the evaporation
and the radiation from the skin are impeded, and less heat, in
consequence, is abstracted from the body. If the articles of apparel
possess the property of retaining air in their meshes, as flannel, the
removal of heat is not as rapid as when linen is worn.

_Observation._ In winter, although more heat is generated in the
system than in summer, yet we require more clothing, and also those
articles that are poor conductors of heat, because caloric is more
rapidly extracted in clear, cold weather, than in a warm day.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does the preceding remark explain? 579. What suggestion
respecting the condition of the skin before taking a walk or ride in a
cold day? Why? 580. Do the amount and kind of clothing affect animal
heat? What is said of well-clothed persons? When does the system
generate the most heat?

  -=-=-=-=-=-=-=-=-=-=-=-=

581. _The health and constitution influence the generation of heat._
When the health is firm, and the constitution vigorous, less clothing
is needed, for the change among the particles of matter is more rapid,
and more heat is generated, than when the opposite condition obtains.
Persons of a feeble constitution, particularly, if any of the vital
organs[18] are diseased, need more clothing and require rooms of a
warmer temperature, than individuals who are free from disease and
have a vigorous constitution.

  [18] The brain, lungs, heart, and digestive organs, are called _vital_
       organs.

_Observation._ Persons who are infirm, and whose vital powers are
feeble, in general, accustom themselves to an undue amount of clothing
and warm rooms. A more judicious practice would be, to exercise more
and use a moderate amount of clothing, together with a more nutritious
diet.

582. _The surplus heat should be removed equally from all parts of the
system._ The rapid evaporation of fluids, as in free perspiration, or
from radiation, as in a cold atmosphere, is attended with a removal of
heat from the system. This modifies the action of the circulatory
vessels. Consequently, if heat is suddenly and rapidly abstracted from
one part of the system, the equilibrium of the circulation is
destroyed, which will produce disease.

  -=-=-=-=-=-=-=-=-=-=-=-=

Why do we, then, require more clothing in winter than in summer? 581.
Why do persons of firm health and vigorous constitutions need less
clothing than those who are feeble? What is a general practice among
infirm persons? What would be more judicious? 582. Why should the
surplus heat be removed equally from all parts of the system? What is
said respecting currents of air from small apertures?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Currents of air that impinge upon small portions of the
body, as from small apertures, or from a window slightly raised,
should be avoided. They are more dangerous than to expose the whole
person to a brisk wind, because the current of air removes the heat
from the part exposed, which disturbs the circulation of blood and
causes disease, usually in the form of "colds." For the same reason,
it is not judicious to stand in an open door, or the opening of a
street.

583. _The system suffers less when the change of temperature is
gradual._ The change in the production of heat, as well as in the
evaporation of fluids from the system, is gradual when not influenced
by foreign causes. This gradual change is known under the name
_acclimation_. By this means the body is enabled to endure tropical
heat and polar cold. Owing to this gradual adaptation of the system to
different temperatures, we can bear a greater degree of heat in the
summer between the tropics, than in the winter under the polar
circles. On the other hand, we can endure a greater degree of cold in
winter and in the arctic region, than in the summer and in equatorial
countries.

584. The sensation of heat which would be oppressive in a mild, warm
day of January, would only be grateful in July, and a degree of cold
which could scarcely be endured in August, would not be uncomfortable
in December. The changes of season in our latitude prevent the
disagreeable and perhaps fatal consequence that would follow, if no
spring or autumn intervened between the severity of winter's cold and
the intensity of summer's heat. During the transition periods, the
constitution is gradually changed, and adapted to bear the extremes of
temperature without suffering. The amount of heat generated in the
nutrient capillary vessels, is likewise diminished or increased as the
temperature of the season becomes greater or less.

  -=-=-=-=-=-=-=-=-=-=-=-=

583. In what manner should change of temperature take place, to be
adapted to the body? How is the body enabled to endure tropical heat
and polar cold? State some of the effects of the gradual adaptation of
the system to different temperatures. 584. What is said relative to a
warm day in winter? To a cold day in summer? What is said of the
changes of seasons in our latitude? What effect on the constitution
during spring and autumn? What change in the amount of heat
generated?

  -=-=-=-=-=-=-=-=-=-=-=-=

585. But, on the contrary, we cannot suddenly pass from one extreme of
temperature to the other with impunity. Let an inhabitant of Quebec
suddenly arrive in Cuba in February, and he would suffer from languor
and exhaustion; after becoming acclimated to this tropical climate,
let him suddenly return to Quebec in January, and the severity of the
weather would be almost insupportable.

_Observations._ 1st. Experience shows that heated rooms, as well as
tropical climates, lessen the generation of heat in the body, and
likewise the power of resisting cold. It would be idle for the
merchant from his warehouse, or the mechanic from his heated shop, to
attempt to sit on the box with a coachman, with the same amount of
clothing as his companion, who is daily exposed to the inclemency of
the weather.

2d. "It is the power of endurance of cold at one period, and the
absence of its necessity at another, that enables animals, in
their wild and unprotected state, to bear the vicissitudes of the
seasons with so little preparation in clothing, and so little real
inconvenience."

  -=-=-=-=-=-=-=-=-=-=-=-=

585. What effect on the system has a sudden transition from a cold to
a warm climate? What does experience show? Why do wild animals bear
the vicissitudes of the seasons with so little preparation in
clothing?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXIX.

THE VOICE.


586. The beautiful mechanism of the vocal instrument, which produces
every variety of sound, from a harsh, unmelodious tone, to a soft,
sweet, flute-like sound, has, as yet, been imperfectly imitated by
art. It has been compared, by many physiologists, to a wind, reed, and
stringed instrument. This inimitable, yet simple instrument, is the
_Lar´ynx_.

587. Incidentally, the different parts of the respiratory organs, as
well as the larynx, are subservient to speaking and singing. The
tongue, nasal passages, muscles of the fauces and face, are agents
which aid in the intonation of the voice.


ANATOMY OF THE VOCAL ORGANS.

588. The LARYNX is a kind of cartilaginous tube, which, taken as a
whole, has the general form of a hollow, reversed cone, with its base
upward toward the tongue, in the shape of an expanded triangle. It
opens into the pharynx, at its superior extremity, and communicates,
by its inferior opening with the trachea. It is formed by the union of
five cartilages, namely, the _Thy´roid_, the _Cri´coid_, the two
_A-ryt-e´noid_, and the _Ep-i-glot´tis_. These are bound together by
ligaments, and moved by muscles.

  -=-=-=-=-=-=-=-=-=-=-=-=

586. What is said of the structure of the vocal instrument? With what
instrument have physiologists compared it? What is the vocal
instrument called? 587. What organs are called into action in speaking
beside the larynx? 588-596. _Give the anatomy of the vocal organs._
588. Describe the larynx. Name the cartilages that form the larynx.

  -=-=-=-=-=-=-=-=-=-=-=-=

589. The THYROID CARTILAGE is the largest of the five, and forms the
prominence in the front of the neck, called _Po´mum A-da´mi_, (Adam's
apple.) It is composed of two parts, and is connected with the bone of
the tongue above, and with the cricoid cartilage below.

590. The CRICOID CARTILAGE takes its name from its resemblance to a
ring. It is situated below the thyroid cartilage, it is narrow in
front, broader at the sides, and still broader behind, where it is
connected with the thyroid cartilage. Below, it connects with the
first ring of the trachea.

[Illustration: Fig. 102. A side view of the cartilages of the larynx. *
The front side of the thyroid cartilage. 1, The os hyoides, (bone at the
base of the tongue.) 2, The ligament that connects the hyoid bone and
thyroid cartilage. 3, 4, 5, The thyroid cartilage. 6, The cricoid
cartilage. 7, The trachea.]

[Illustration: Fig. 103. A posterior view of the cartilages and ligaments
of the larynx. 1, The posterior face of the epiglottis. 3, 3, The os
hyoides. 4, 4, The lateral ligaments which connect the os hyoides and
thyroid cartilage. 5, 5, The posterior face of the thyroid cartilage. 6,
6, The arytenoid cartilages. 7, The cricoid cartilage. 8, 8, The junction
of the cricoid and the arytenoid cartilages. 12, The first ring of the
trachea.]

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589. Describe the thyroid cartilage. 590. From what does the cricoid
cartilage derive its name? Where is it situated? Explain fig. 102.
Fig. 103.

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591. The ARYTENOID CARTILAGES are small triangular bodies placed upon
the back part of the cricoid cartilage. They are connected with the
thyroid cartilages, by four ligaments, called _Vo´cal Cords_.

592. The EPIGLOTTIS is fibro-cartilaginous, and is placed behind the
base of the tongue. In shape it resembles a leaf of parsley.

593. The VOCAL CORDS, or ligaments, are formed of elastic and parallel
fibres, enclosed in a fold of mucous membrane. They are about two
lines in width, and pass from the anterior angle of the thyroid
cartilage, to the two arytenoid cartilages. The one is called the
superior, and the other the inferior vocal ligament. The cavity, or
depression between the superior and inferior ligament, is called the
_ventricle_ of the larynx. The aperture, or opening between these
ligaments, is called the _glot´tis_, or _chink of the glottis_. It is
about three fourths of an inch in length, and one fourth of an inch in
width, the opening being widest at the posterior part. This opening is
enlarged and contracted by the agency of the muscles appropriated to
the larynx.

[Illustration: Fig. 104. An ideal, lateral section of the larynx. 1, 1,
The upper vocal cords. 2, 2, The lower vocal cords. 3, 3, The glottis. 4,
4, The ventricles of the larynx.]

[Illustration: Fig. 105. A vertical section of the larynx. 2, The os
hyoides. 4, The apex of the epiglottis. 7, The superior vocal ligament.
9, The ventricle of the larynx. 10. The lower vocal ligament. 11, The
arytenoid cartilage. 12, 13, The cricoid cartilage. 14, The trachea. 18,
The oesophagus.]

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591. Describe the arytenoid cartilages. 592. What is said of the
epiglottis? 593. Give the structure of the vocal cords. Where is the
ventricle of the larynx? Where is the glottis situated? What is
represented by fig. 104? Explain fig. 105.

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[Illustration: Fig. 106. A view of the larynx from above, showing the
vocal ligaments. 1, The anterior edge of the larynx. 4, The posterior
face of the thyroid cartilage. 5, 5, The arytenoid cartilages. 6, 6, The
vocal ligaments. 7, Their origin, within the angle of the thyroid
cartilage. 9, Their termination, at the base of the arytenoid cartilages.
8, 10, The glottis.]

594. The larynx is connected by muscles with the sternum, oesophagus,
base of the skull, hyoid bone, lower jaw, and tongue. This organ is
supplied with a large number of blood-vessels, and it likewise
receives nerves from the sympathetic system, and two large nerves from
the tenth pair. The number and size of the nervous filaments
distributed to the mucous membrane of the larynx, render it more
sensitive than any other portion of the respiratory organs.

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How is the glottis enlarged or contracted? Explain fig. 106. 594. By
what means and to what organs is the larynx connected? Why is the
larynx more sensitive than other parts of the respiratory organs?

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595. The larynx is much more developed and prominent in man than in
woman. In the former, the anterior angle of the thyroid cartilage is
acute, while in the latter it is rounded, and the central slope of the
superior border of the same cartilage is less deep, and the epiglottis
smaller and less prominent, than in man.

596. The difference in the formation of the larynx in infancy is less
striking; but at a later period, it is more developed in the male than
in the female. It is very remarkable that this increase is not
progressive, like that of other organs, but, on the contrary, develops
itself at once at the period of puberty.


PHYSIOLOGY OF THE VOCAL ORGANS.

597. In the formation of the voice, each part already described
performs an important office. The cricoid and thyroid cartilages give
form and stability to the larynx; the arytenoid cartilages, by their
movement, vary the width of the glottis. The epiglottis is flexible
and elastic. When it is erect, the chink of the glottis is open, as in
inspiration; when depressed, as in swallowing food and drink, it
covers and closes this aperture. It prevents the introduction of
articles of food into the trachea, and probably modifies sound as it
issues from the glottis.

598. The muscles of the neck elevate and depress the larynx; the
muscles of the larynx increase or diminish the width of the glottis;
at the same time, the vocal cords are relaxed or tightened, while the
muscles of the face open and close the mouth.

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595. What difference between the formation of the larynx of the female
and that of the male? 596. Does this difference exist in childhood? Is
its development progressive? 597-600. _Give the physiology of the
vocal organs._ 597. Which cartilages give stability and form to the
larynx? Which vary the width of the glottis? What is the function of
the epiglottis? 598. What effect have the muscles of the neck upon the
larynx? The use of the muscles of the larynx?

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599. The elasticity of the ribs and the contraction of the abdominal
muscles diminish the cavity of the chest, and the air, in consequence,
is pressed from the air-cells into the bronchial tubes and trachea. It
then rushes by the vocal cords, and causes a peculiar vibration, which
produces _sound_.

_Observations._ 1st. Experiments have satisfactorily shown that the
vocal cords are the principal agents in the formation of the voice.
The tongue, which many have supposed to be the most important organ in
speaking, is not essential to sound. In several instances it has been
removed, and the persons thus mutilated could speak with fluency.

2d. When the vocal cords are ulcerated, or inflamed, however slightly,
as in sore throat produced by a cold, the voice will be changed. The
loss of speech among public speakers is generally produced by a
relaxation of the vocal ligaments. Hence, bronchitis is a misnomer for
this affection.

600. Sound is varied by the velocity of the expelled current of air,
and the tension of the vocal ligaments. The size of the larynx, the
volume and health of the lungs, the condition of the fauces and nasal
passages, the elevation and depression of the chin, the development
and freedom of action of the muscles which are attached to the larynx,
the opening of the mouth, the state of the mind, and general health of
the system, influence the modulations of sound.

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What effect has the combined action of these muscles? 599. How is
sound produced? What have experiments shown? What effect has disease
of the vocal ligaments upon the voice? 600. How is sound varied?
Mention other conditions that contribute to the modulation of sound.

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CHAPTER XXX.

HYGIENE OF THE VOCAL ORGANS.


601. _The voice can be changed and modified by habit._ Sailors,
smiths, and others, who are engaged in noisy occupations, exert their
vocal organs more strongly than those of more quiet pursuits. This not
only affects the structure of the vocal organs, but varies the
intonation of the voice.

602. _The voice is strong in proportion to the development of the
larynx, and the capacity of the chest._ Singing and reading aloud
improve and strengthen the vocal organs, and give a healthy expansion
to the chest. The enunciation of the elementary sounds of the English
language, aids in developing the vocal organs, as well as preventing
disease of the throat and lungs. This exercise also conduces to the
acquisition of musical sounds.

603. _The attitude affects the modulation of the voice._ When an
individual stands erect, the movements of the whole respiratory
apparatus are most free and effective. The larynx is brought forward
by the erect position of the head and the elevation of the chin. The
muscles of the arytenoid cartilages are then brought to a proper
relation for action, by which a tension of the vocal cords is
produced, that favors clear and harmonious enunciation.

_Experiment._ Read with the head bowed forward and the chin depressed;
then read with the head erect and the chin elevated, and the
difference in the movement of the vocal organs, together with the
difference in the voice, will be manifest.

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601-616. _Give the hygiene of the vocal organs._ 602. How may the
voice be strengthened? 603. What effect has the erect attitude upon
the modulations of the voice? Give the experiment.

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[Illustration: Fig. 107. An improper position; but one not unfrequently
seen in some of our common schools, and in some of our public speakers.]

[Illustration: Fig. 108. The proper position for reading, speaking, and
singing.]

604. If an individual or class read or sing when sitting, let the
position represented by fig. 109 be adopted, and not the one
represented by fig. 110; for the erect position in sitting conduces to
the free and effective action of the respiratory and vocal organs, and
is as important as the erect attitude in standing.

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604. What position should be adopted when a person reads or sings when
sitting? Why?

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605. _The muscles of the neck should not be compressed._ If the
muscles of the neck and larynx are compressed by a high cravat, or
other close dressing, not only will the free and energetic movements
of these parts be impeded, but the tones will be feeble and
ineffective. Therefore the dress of the neck, particularly of public
speakers and singers, should be loose and thin. For a warm dress upon
the neck, when the vocal organs are in action, will induce too great a
flow of blood to these parts, which will be attended by subsequent
debility.

[Illustration: Fig. 109.]

_Observations._ 1st. The loss of voice, (_lar-yn-gi´tis_,) which is
prevalent among public speakers, may be ascribed in part to the
injudicious dressing of the neck, and improper position in standing.

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605. How should public speakers dress their necks? Why? What is a
common cause of the loss of voice?

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2d. When individuals have been addressing an audience in a warm room,
or engaged in singing, they should avoid all impressions of a cold
atmosphere, unless adequately protected by an extra garment.

[Illustration: Fig. 110.]

606. _The condition of the air modifies speaking and singing._ As pure
air is more elastic and resonant than impure, and as easy, melodious
speaking or singing requires atmospheric elasticity, so school-rooms
and singing-halls should be well ventilated, if we would be
entertained with soft intonations in reading, or sonorous singing.

_Observation._ The imperfect ventilation of churches and vestries is
another cause of laryngitis among clergymen. This affection is almost
unknown among those who speak in very open rooms, where stoves are not
used.

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Give 2d. observation. 606. Why does easy and melodious speaking
require pure air? What is another cause laryngitis among clergymen?

  -=-=-=-=-=-=-=-=-=-=-=-=

607. _The condition of the nasal passages and throat modifies the
voice._ The enunciation of words is rendered more or less distinct, in
proportion as the jaws are separated in speaking, and the fauces and
nasal passages are free from obstruction. For these reasons, the
scholar should be taught to open the mouth adequately when reading,
speaking, or singing, that the sounds formed in the larynx and
modified in the fauces may have an unobstructed egress.

_Observations._ 1st. If the fauces are obstructed by enlarged tonsils,
(a condition by no means uncommon in children,) they should be removed
by a surgical operation, which is not only effective, but safe, and
attended with little suffering. The tonsils are situated on each side
of the base of the tongue, and, when enlarged, they obstruct the
passage through which the air passes to and from the lungs, and the
respiration is not only laborious, but distressing.

2d. When the nasal passages are obstructed, there is a peculiar sound
of the voice, which is called "talking through the nose." This
phenomenon arises, not from the expired air passing through the nose,
but from its not being able to pass through the nasal passages.

608. _The state of the mind and health exerts an influence upon the
vocal organs._ "The organs of the voice, in common with all other
parts of the bodily frame, require the vigor and pliancy of muscle,
and the elasticity and animation of mind, which result from good
health, in order to perform their appropriate functions with energy
and effect. But these indispensable conditions to the exercise of
vocal organs, are, in the case of most learners, very imperfectly
supplied."

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607. Does the condition of the throat and nasal passages modify the
voice? Name the influences that produce clear enunciation of words.
What is the effect when the nasal passages are obstructed? 608. How
are the vocal organs influenced? What do they require?

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609. "A sedentary mode of life, the want of invigorating exercise,
close and long-continued application of mind, and, perhaps, an
impaired state of health, or a feeble constitution, prevent, in many
instances, the free and forcible use of those muscles on which voice
is dependent. Hence arises the necessity of students of elocution
practising physical exercises adapted to promote general muscular
vigor, as a means of attaining energy in speaking; the power of any
class of muscles being dependent on the vigor of the whole system."

610. "Gymnastic and calisthenic exercises are invaluable aids to the
culture and development of the voice, and should be sedulously
practised when opportunity renders them accessible. But even a slight
degree of physical exercise, in any form adapted to the expansion of
the chest and to the freedom and force of the circulation, will serve
to impart energy and glow to the muscular apparatus of voice, and
clearness to its sound."

611. "There is, therefore, a great advantage in always practising some
preliminary muscular actions, as an immediate preparation for vocal
exercises. The art of cultivating the voice, however, has, in addition
to the various forms of corporeal exercise, practised for the general
purpose of promoting health, its own specific prescription for
securing the vigor of the vocal organs, and modes of exercise adapted
to the training of each class of organs separately."

612. The results of such practice are of indefinite extent. They are
limited only by the energy and perseverance of the student, excepting
perhaps in some instances of imperfect organization. A few weeks of
diligent cultivation are usually sufficient to produce such an effect
on the vocal organs, that persons who commence practice with a feeble
and ineffective utterance, attain, in that short period, the full
command of clear, forcible, and varied tone.

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609. Why are students of elocution in general necessitated to practise
physical exercise? 610. What are invaluable aids in the culture of the
voice? 611. What is said of the art of cultivating the voice? 612. Are
the results of such practices limited? What exception?

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613. _Repetition is essential to distinct articulation of words._ In
teaching a child to articulate a letter or word, in the first
instance, make an effort to induce a proper state of the vocal organs
by which the particular sound is produced. Repeat the letter or word
again and again, until all the parts of the vocal apparatus harmonize
in their movements to produce the given sound. This repetition is as
necessary in learning to read as in singing.

_Observations._ 1st. There is nothing gained by trying to teach a
child to pronounce the letters of the alphabet, before the vocal
organs are so developed that distinct utterance can be given to the
proper sounds.

2d. The drawling method of talking to young children, as well as using
words that are not found in any written language, (called child's
talk,) is decidedly wrong. A child will pronounce and understand the
application of a correct word as quickly as an incorrect one.

614. _No part of the vocal organs is wanting, with those individuals
that stammer, or who have an impediment in their speech._ Some parts
may be more developed than others, but they generally are but
imperfectly under the control of the will, and assume an irregular and
rapid movement, while other parts, the motions of which are essential,
remain comparatively inactive. This can be seen by comparing the
movements of the lips, tongue, and larynx, while attempting to speak,
in a person who stammers, with the movements of the corresponding
parts, while speaking, in an individual who has no such impediment.

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613. Is repetition essential to distinct articulation? What method is
suggested in teaching a child to articulate letters or words? Give
observation 1st. Observation 2d. 614. Are the vocal organs wanting in
stammerers? Why the defect in their articulation of words?

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615. Surgical operations and medical treatment are not highly
advantageous in a majority of these cases. In the young and middle
aged, this defect can be remedied by _patient_ and judicious training.
At first, only those letters and words should be spoken that can be
articulated with distinctness. Let there be repetition, until the
words can be spoken at any time with readiness. Then take for a lesson
other words, more difficult to articulate; and pursue a similar
process of training and repetition, until every part of the vocal
organs can be called into a ready and harmonious action in giving
utterance to any word in common use.

616. _The method of removing foreign bodies from the throat._ It is
not necessary to ascertain which passage the foreign body is in, for
the immediate treatment ought in either case to be the same. Some
person should place one hand on the front of the chest of the
sufferer, and, with the other, give two or three smart blows upon the
back, allowing a few seconds to intervene between them. This treatment
will generally be successful, and cause the substance to be violently
thrown from the throat.

_Observation._ If the foreign body passes into the larynx violent
spasmodic coughing immediately succeeds, which continues until it is
removed or life is extinct. Such cases demand the prompt opening of
the trachea below the larynx by a skilful surgeon.

  -=-=-=-=-=-=-=-=-=-=-=-=

615. How can stammering be remedied? 616. What is the method of
removing foreign bodies from the throat?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXXI.

THE SKIN.


617. The skin is a membrane which envelops the muscles and other parts
of the system. In youth, and in females particularly, it is smooth,
soft, and elastic. In middle age, and in males, it is firm and rough
to the touch. In old age, in persons who are emaciated, and about the
flexions of the joints, it is thrown into folds. The interior of the
body, like the exterior, is covered by a skin, which, from the
constantly moistened state of its surface, is called the mucous
membrane. At the various orifices of the body, the exterior skin is
continuous with the internal.


ANATOMY OF THE SKIN.

618. The SKIN, to the naked eye, appears composed of one membrane. But
examination has shown that it consists of two layers of membrane,
namely, the _Cu´ti-cle_, (scarf-skin,) and the _Cu´tis Ve´ra_, (true
skin.) These layers are widely different from each other in structure,
and perform very different offices in the animal economy.

619. The CUTICLE (sometimes called the _ep-i-derm´is_) is the external
layer of the skin. This membrane is thin and semi-transparent, and
resembles a thin shaving of soft, clear horn, and bears the same
relation to other parts of the skin that the rough bark of a tree does
to the liber, or living bark. The cuticle has no perceptible nerves or
blood-vessels; consequently, if it is cut or abraded, no pain will be
felt, and no fluid will ooze from it.

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617. What is the skin? Mention its different appearances in its
different conditions in the human frame. Is the interior of the body,
as well as the exterior, covered by a skin? What is the interior
membrane called? Why has it received this name? 618-636. _Give the
anatomy of the skin._ 618. What is said of the skin? What is said
relative to these layers of membrane? 619. Describe the cuticle. What
name is sometimes applied to the cuticle?

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_Experiment._ Pass a pin through the portion of the cuticle that
skirts the nails, or remove a thin shaving from the palm of the hand,
and no painful sensation will be experienced unless the pin or knife
penetrates deeper than the cuticle.

620. This membrane varies in thickness on different parts of the
body,--from the thin, delicate skin upon the internal flexions of the
joints, to the thickened covering of the soles of the feet. The
greater thickness of the cuticle of the palms of the hands and soles
of the feet, is manifestly the intentional work of the Creator; for it
is perceptible in infants, even at birth, before exercise can have had
any influence.

621. The CUTIS VERA (sometimes called the _co´ri-on_) is composed of
minute fibres, which are collected into small bundles or strands.
These are interwoven with each other so as to constitute a firm,
strong, and flexible web. In the superficial part of the true skin,
the web is so close as to have the appearance of felt-cloth; but more
deeply, the pores become progressively larger, and, upon the lower
surface, have a diameter of about a line, or one twelfth of an inch.
This gives the under surface the appearance of a coarse web. The
strands of the under surface of the true skin are connected with the
fibrous web, in which the sub-cutaneous fat of the body is deposited;
while the upper surface gives support to the sensitive, or papillary
layer, which is bedded upon it.

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Give the experiment. 620. What is said of the thickness of the cuticle
in different parts of the body? 621. Describe the cutis vera. By what
name is it sometimes called? What is the appearance of the upper
surface of the cutis vera? Of the under surface?

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_Observation._ When the skins of animals are immersed in a strong
solution of oak or hemlock bark, a chemical union takes place between
the gelatin, of which the true skin is mostly composed, and the tannin
of the bark. By this process leather is formed, and its peculiar
markings are owing to the papillary layer.

[Illustration: Fig. 111. An ideal representation of the papillæ. 1, 1,
The cutis vera. 2, 2, The papillary layer. 3, 3, The arteries of the
papillæ. 4, 4, The veins of the papillæ. 5, 5, The nerves of the papillæ.]

622. The sensitive layer of the skin is thin, soft, uneven, pinkish in
hue, and composed of blood-vessels, which confer its various tints of
red; and of nerves, which give it the faculty of sensation. The
unevenness of this layer is produced by small, elongated, conical
prominences, called _Pa-pil´læ_.

623. Each PAPILLA is composed of a minute artery, vein, and nerve.
Some of the prominences are arranged in concentric ovals, as may be
seen on the ends of the fingers; others are more or less parallel, and
pursue a serpentine course; some suddenly diverge, and again reunite,
as may be seen in the palm of the hand. Papillæ are found in every
part of the skin. Consequently, their number is very great.

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How is leather formed? 622. What is the appearance of the sensitive
layer? What causes the unevenness of this layer? Explain fig. 111.
623. Describe the papillæ.

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624. The cutis vera contains not only _Arteries_, _Veins_, and
_Nerves_ but _Lymphatics_, _Oil-Glands_ and _Tubes_, and _Perspiratory
Glands_ and _Tubes_.

[Illustration: Fig. 112. The arteries and veins of a section of the skin.
A, A, Arterial branches. B, B, Capillary, or hair-like vessels, in which
the large branches terminate. C, The venous trunk, collecting the blood
from the capillaries.]

625. The ARTERIES AND VEINS of the skin are very numerous. The larger
branches of the arteries pass through the open meshes of the true
skin, and are subdivided into a myriad of minute capillary vessels,
which form a beautiful net-work on the upper surface of the true skin.
This vascular net sends a branch to each of the papillæ, which opens
into and terminates in a minute vein. The capillary veins are as
numerous as the arteries which they accompany. They unite and form
larger trunks, as small springs from the hill side coalesce to form
rivulets.

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624. What vessels are found in the cutis vera? Explain fig. 112. 625.
What is said of the cutaneous arteries? Of the cutaneous veins?

  -=-=-=-=-=-=-=-=-=-=-=-=

626. The NERVES that are spread over every part of the sensitive layer
of the true skin, proceed from the spinal cord. As a proof of the
great number of nervous filaments in the skin, no part of this tissue
can be punctured with a fine needle without transfixing a nerve, and
inducing pain. In some parts of the system, however, the nerves are
more abundant than in others; where the sense of feeling is most
acute, we find the greatest number of nerves, and those of the largest
size. Those parts that are most exposed to injury are most sensitive.

_Examples._ 1st. The conjunctiva, or skin of the eye, is pained by the
presence of a particle of dust, because it would render vision
imperfect.

2d. The lungs, also, would be injured by the smallest particle of
matter; they are therefore protected by the exquisite sensitiveness of
the lining membrane of the trachea, so that a particle of food or dust
is ejected by a convulsive cough before it reaches the lungs.

627. The nerves are more numerous in the upper than lower extremities;
in greater numbers upon the palm than the back of the hand. They are,
likewise, more abundant and larger at the extremities of the fingers,
and in the lips, than in any other part of the skin.

_Observation._ The proboscis of the elephant, the extremities of the
tails of certain species of monkeys, and the tentacula of some kinds
of fish, receive a more abundant supply of sensitive nerves than other
parts of their systems.

  -=-=-=-=-=-=-=-=-=-=-=-=

626. Where do the nerves of the skin proceed from? Are they numerous
in this membrane? How is it proved? What is said of those parts most
exposed to injury? Give example 1st. Example 2d. 627. Mention the
difference in the distribution of the nerves in various parts of the
body. Is this difference found in the lower order of animals?

  -=-=-=-=-=-=-=-=-=-=-=-=

628. In the small papillæ, the nerve forms a single loop, while in
papillæ of larger size, and endowed with a power of more exalted
sensation, the nerve is bent several times upon itself previous to
completing the loop. These little loops spring from a net-work of
nerves, imbedded in the upper porous layer of the true skin, at the
base of the papillæ. This net-work of nerves receives its influence
through nerves which take their winding course through the fat
distended openings of the deeper layers of the true skin.

[Illustration: Fig. 113. 1, 1, The cuticle. 2, 2, The colored layer of
the cuticle. 3, 3, The papillary layer, exhibiting the nerves as they
form loops. 4, 4, The net-work of nerves. 5, 5, The true skin. 6, 6, 6,
Three nerves that divide to form the net-work (4, 4.) 7, 7, 7, The
furrows between the papillæ. 8, 8, 8, Three papillæ magnified fifty
diameters.]

629. The LYMPHATICS are found in great numbers in the true skin, and
they are so minute that they cannot be seen with the naked eye; but
when these hair-like vessels are injected with quicksilver, (a work of
great difficulty,) the surface injected resembles a sheet of silver.
In this way their existence can be imperfectly demonstrated. They are
a part of the vascular net-work situated upon the upper surface of the
true skin. Each papilla is supplied with a lymphatic filament, the
mouth of which opens beneath, and lies in contact with the under
surface of the cuticle. This net-work of vessels communicates through
the open meshes of the true skin with larger lymphatic trunks, that
open into the venous system.

  -=-=-=-=-=-=-=-=-=-=-=-=

628. How are the nerves of the small papillæ arranged? How in the
large papillæ? What does fig. 113 represent? 629. What is said of the
cutaneous lymphatics? How is their existence proved?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 114. A plexus of lymphatic vessels in the skin,
considerably magnified from an injected preparation.]

630. The OIL-GLANDS are small bodies imbedded in the true skin. They
connect with the surface of the skin by small tubes, which traverse
the cuticle. In some parts, these glands are wanting; in others, where
their office is most needful, they are abundant, as on the face and
nose, the head, the ears, &c. In some parts, these tubes are spiral;
in others, straight. These glands offer every shade of complexity,
from the simple, straight tube, to a tube divided into numberless
ramifications, and constituting a little rounded tree-like mass, about
the size of a millet seed.

  -=-=-=-=-=-=-=-=-=-=-=-=

Of what are they a part? 630. Describe the oil-glands. With what do
they connect? Do they exist in every part of the body? Of what form
are their tubes?

  -=-=-=-=-=-=-=-=-=-=-=-=

631. In a few situations, these small glands are worthy of particular
notice, as in the eyelids, where they possess great elegance of
distribution and form, and open by minute pores along the lids; in the
ear-passages, where they produce that amber-colored substance, known
as the _ce-ru´men_, (wax of the ears,) and in the scalp, where they
resemble small clusters of grapes, and open in pairs into the sheath
of the hair, supplying it with a pomatum of Nature's own preparing.
The oil-tubes are sometimes called the _se-ba´ceous fol´li-cles_.

[Illustration: 4. A small hair from the scalp, with its oil-glands. The
glands (A) form a cluster around the shaft of the hair-tube, (C.) These
ducts open into the sheath of the hair, (B.) All the figures, from 1 to
4, are magnified thirty-eight diameters.]

  -=-=-=-=-=-=-=-=-=-=-=-=

631. What is said of these tubes in the eyelids? In the ear? In the
scalp? What are these glands sometimes called?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Among the inhabitants of cities, and especially in
persons who have a torpid state of the skin, the contents of the
oil-tubes become too dense and dry to escape in the usual manner. Thus
it collects, distends the tube, and remains until removed by art. When
this impacted matter reaches the surface, dust and smoke mix with it,
then it is recognized by small, round, dark spots. These are seen on
the forehead, nose, and other parts of the face. When this matter is
pressed out, the tube gives it a cylindrical form. The parts around
the distended tubes sometimes inflame. This constitutes the disease
called, _"ac´ne punc-ta´ta."_

632. The PERSPIRATORY APPARATUS consists of minute cylindrical tubes,
which pass inward through the cuticle, and terminate in the deeper
meshes of the cutis vera. In their course, each little tube forms a
beautiful spiral coil; and, on arriving at its destination, coils upon
itself in such a way as to constitute an oval-shaped, or globular
ball, called the _perspiratory gland_.

633. The opening of the perspiratory tube on the surface of the
cuticle, namely, "the pores," is also deserving of attention. In
consequence of its extremity being a section of a spirally-twisted
tube, the aperture is oblique in direction, and possesses all the
advantages of a valvular opening, preventing the ingress of foreign
injurious substances to the interior of the tube and gland.

634. "To arrive at something like an estimate of the value of the
perspiratory system, in relation to the rest of the organism, I
counted the perspiratory pores on the palm of the hand, and found 3528
in a square inch. Now each of these pores being the aperture of a
little tube about a quarter of an inch long, it follows, that in a
square inch of skin on the palm of the hand there exists a length of
tube equal to 882 inches, or 73½ feet. Surely such an amount of
drainage as seventy-three feet in every square inch of skin--assuming
this to be the average for the whole body--is something wonderful and
the thought naturally intrudes itself, What if this _drainage_ be
obstructed?

  -=-=-=-=-=-=-=-=-=-=-=-=

What is said of the retention of the unctuous matter in the oil-tubes?
632. Of what does the perspiratory apparatus consist? 633. What is
peculiar in the opening of the perspiratory tubes on the surface of
the cuticle? 634. How many perspiratory pores did Dr. Wilson count
upon a square inch of skin on the palm of the hand?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 116. A perspiratory gland from the palm of the hand,
magnified forty diameters. 1, 1, A twisted tube composing the gland. 2,
2, The two excretory ducts from the gland. These unite to form one spiral
tube, that perforates the cuticle, (3,) and opens obliquely on its
surface at 4. The gland is imbedded in cells filled with fat, which are
seen at 5, 5.]

  -=-=-=-=-=-=-=-=-=-=-=-=

What does fig. 116 represent?

  -=-=-=-=-=-=-=-=-=-=-=-=

635. "Could we need a stronger argument for enforcing the necessity of
attention to the skin? On the pulps of the fingers, where the ridges
of the sensitive layer of the true skin are somewhat finer than in the
palm of the hand, the number of pores on a square inch a little
exceeded that of the palm; and on the heels, where the ridges are
coarser, the number of pores on the square inch was 2268, and the
length of the tube 567 inches, 47¼ feet.

636. "To obtain an estimate of the length of tube of the perspiratory
system of the whole surface of the body, I think that 2800 might be
taken as a fair average of the number of pores in the square inch; and
consequently, 700, the number of inches in length. _Now, the number of
square inches of surface in a man of ordinary height and bulk is 2500;
the number of pores, therefore, 7,000,000; and the number of inches of
perspiratory tube is 1,750,000; that is, 145,833 feet, or 48,611
yards, or nearly TWENTY-EIGHT miles!_"--_Wilson._

  -=-=-=-=-=-=-=-=-=-=-=-=

Give other computations in this paragraph. 635. What is said of the
number of these pores on the pulp of the fingers? On the heels? 536.
What is an average number of pores and length of tube of the whole
surface of the body? Give the summary of the number of pores, and
number or inches of perspiratory tube.

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXXII.

PHYSIOLOGY OF THE SKIN.


637. The skin invests the whole of the external surface of the body,
following all its prominences and curves, and gives protection to all
the organs it encloses, while each of its several parts has a distinct
use.

638. The cuticle is insensible, and serves as a sheath of protection
to the highly sensitive skin (_cutis vera_) situated beneath it. The
latter feels; but the former blunts the impression which occasions
feeling. In some situations, the cuticle is so dense and thick, as
wholly to exclude ordinary impressions. Of this we see an example in
the ends of the fingers, where the hard and dense nail is the cuticle
modified for the purpose referred to. Were the nervous tissue of the
true skin not thus protected, every sensation would be so acute as to
be unpleasant, and contact with external bodies would cause pain.

639. The cuticle, also, prevents disease, by impeding the evaporation
of the fluids of the true skin, and the absorption of the poisonous
vapors, which necessarily attend various employments. It, however,
affords protection to the system only when unbroken, and then, to the
greatest degree, when covered with a proper amount of oily secretion
from the oil-glands.

640. The cuticle is, originally, a transparent fluid, exuded by the
blood-vessels, and distributed as a thin layer on the surface of the
true skin. While successive layers are formed on the exterior of the
true skin, the external cuticular layers are converted into dry,
flattened scales, by the evaporation of their fluid contents. The
thickness of the cuticle is formed mainly from these scales.

  -=-=-=-=-=-=-=-=-=-=-=-=

637-656. _Give the physiology of the skin._ 637. What is said of the
skin? 638. Give a function of the cuticle. Does it vary in thickness
on different parts of the body? Give examples. 630. Mention another
use of the cuticle. 640. What is the cuticle originally?

  -=-=-=-=-=-=-=-=-=-=-=-=

641. The cuticle is, therefore, undergoing a constant process of
formation and growth at its under part, to compensate for the wear
that is taking place continually on its surface. A proper thickness of
the cuticle is in this manner preserved; the faculty of sensation and
that of touch are properly regulated; the places of the little scales,
which are continually falling off under the united influence of
friction and ablution, are supplied; and an action necessary, not
merely to the health of the skin, but to that of the entire body, is
established.

642. Whenever the cuticle is exposed to moderate and repeated
friction, it becomes thicker and tougher, as may be seen in the
cuticle of the lady's finger that plies the needle and in the hard or
callous appearance of the hands of farmers masons, and other
mechanics. This enables them to handle the utensils and materials used
in their vocations without pain or inconvenience.

_Observations._ 1st. When the joints of the feet are subjected to
moderate and continued pressure or friction, frequently one or more of
the papillæ enlarge. This is accompanied with a thickening of the
layers of the cuticle, which is termed a "callosity," or "corn." These
thickened layers of the cuticle are broad at the top and narrow at the
bottom, and the enlarged mass is conical, with the point innermost.
When pressed upon by a tight shoe, these sensitive papillæ cause
pain.

  -=-=-=-=-=-=-=-=-=-=-=-=

How is the thickness of the cuticle mainly formed? 641. Describe the
changes of this membrane. Show the necessity of this constant growth.
642. How does moderate and repeated friction affect the cuticle? Give
examples. What is the benefit derived from having the cuticle thus
changed? What is the result if the joints of the feet are subjected to
moderate and continued pressure? What is the form of a "corn"?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. To remove these painful excrescences, take a thick piece of soft
leather, somewhat larger than the corn; in the centre punch a hole of
the size of the summit of the corn, spread the leather with adhesive
plaster, and apply it around the corn. The hole in the leather may be
filled with a paste made of soda and soap, on going to bed. In the
morning, remove it, and wash with warm water. Repeat this for several
successive nights, and the corn will be removed. The only precaution
is, not to repeat the application so as to cause pain.

643. Let a person unaccustomed to manual labor, trundle the hand-cart,
or row a boat, for several successive hours, and the cuticle upon the
palms of the hands, instead of becoming thicker by use, is frequently
separated from the subjacent tissues, by an effusion of serum,
(water,) thrown out by the vessels of the true skin. Had the friction
been moderate, and applied at regular intervals, instead of blisters
being formed upon the inside of the hands, material would have been
thrown out to form new layers upon the lower surface of the cuticle.

644. The cuticle is interesting to us in another point of view,
as being the seat of the color of the skin. The difference of
color between the blonde and the brunette, the European and the
African, lies in the cuticle;--in the deeper, and softer, and
newly-formed layers of that structure. In the whitest skin, the
cells of the cuticle always contain more or less of a peculiar
pigment, incorporated with the elementary granules which enter
into their composition. In the white races, the pigmentary tint
is extremely slight, and less in winter than in the summer season.
In the darker races, on the contrary, it is deep and strongly
marked.

  -=-=-=-=-=-=-=-=-=-=-=-=

How can they be removed? What precaution is given? 643. Explain why
those persons unaccustomed to labor, blister their hands in rowing a
boat or performing ordinary manual employment for several successive
hours. 644. In what other point of view is the cuticle interesting? In
what part of it do we find the coloring matter?

  -=-=-=-=-=-=-=-=-=-=-=-=

645. The various tints of color exhibited by mankind, are, therefore,
referable to the amount of coloring principle contained within the
elementary granules of the cuticle, and their consequent depth of hue.
In the negro, the granules are more or less black; in the European of
the south, they are amber-colored; and in the inhabitants of the
north, they are pale and almost colorless.

646. Color of the skin has relation to energy in its action; thus, in
the equatorial region, where light and heat are most powerful, the
skin is stimulated by these agents to vigorous action, and color is
very deep; while in the temperate regions, where light and heat are
not so intense, the lungs, liver, and kidneys relieve the skin of part
of its duties. The colored layer of the cuticle has been called the
_re´te mu-co´sum_, (mucous coat of the skin,) and described as a
distinct layer by many physiologists.

_Observation._ "The various coloring of the inner layer of the cuticle
gives to some animals their varied hues; the serpent, the frog, the
lizard, and some fishes have a splendor of hue almost equal to
polished metal. The gold-fish and the dolphin owe their difference of
color and the brilliancy of their hues to the color of this layer of
the skin."

647. The nerves of the skin are the organs of the sense of touch and
feeling. Through them we receive many impressions that enhance our
pleasures, as the grateful sensations imparted by the cooling breeze
in a warm day. In consequence of their sensitiveness, we are
individually protected, by being admonished of the proximity of
destructive agents.

  -=-=-=-=-=-=-=-=-=-=-=-=

In what season of the year is the coloring matter less in the white
race? 645. To what is the color of the skin referable? 646. Why have
the races of the torrid zone darker complexions than those of the
temperate or frigid zones? What is this colored layer called by many
physiologists? To what is the different hues in animals owing? 647. Of
what use are the nerves of the skin?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Illustration._ A man who had been afflicted some years with a severe
disease of a portion of the brain and spinal cord, was deprived of
feeling in the lower extremities. He was directed by his attending
physician to use a warm footbath. Intending to follow the directions
given him, he immersed his feet in boiling water, which he supposed of
a proper temperature. While his feet were immersed in the water, he
experienced no sensation of an unpleasant nature. On withdrawing them,
he was astonished to find the cuticle separated from the other
tissues, by the effusion of serum, and thus producing a blister over
the whole surface.

648. Portions of the skin would suffer every day, were it not for the
sentinel-like care exercised by the nerves, by which all impressions
are transmitted to the brain. As the skin is continually exposed to
the influence of destructive agents, it is important that the nerves,
provided for its protection, should be kept in a healthy state.

649. A large proportion of the waste of the body passes through the
outlets of the skin; some portions in the form of oil, others in the
form of water and carbonic acid.

650. The oil-glands secrete an oil, partly free and diffused, and
partly mixed with albumen. When the cells are fully formed, that is,
fully distended, they yield their contents, and the fluid matter they
contain is set free, and passes along the tubes to the surface; this
fluid matter constitutes the oily element of the economy of the skin.

651. The uses of the unctuous product of the oil-glands are twofold:
1st. The protection; 2d. The removal of waste matter from the system.
In the exercise of these offices the oily substance is diffused over
those parts of the skin which are naturally exposed to vicissitudes of
temperature and moisture,--as the nose, face, and head;--to the
injurious attrition of contiguous surfaces,--as the flexures of
joints;--or the contact of acrid fluids,--as in the excoriations to
which infants are liable.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give the illustration. 648. Why is it necessary that the cutaneous
nerves be kept in a healthy state? 649. Through what membrane does a
large proportion of the waste material of the system pass? 650. What
is the function of the oil-glands? 651. What are the uses of the oily
product of these glands?

  -=-=-=-=-=-=-=-=-=-=-=-=

652. The oil of the unctuous substance is the principal agent in
effecting these purposes: 1st. It prevents the evaporation or
congelation of the water of the cuticle, which would cause it to
become parched and peel off, thus leaving the sensitive skin exposed.
2d. It affords a soft medium to the contact of moving substances. 3d.
It repels moisture and fluids. 4th. The action of these glands removes
the waste atoms and purifies the blood.

653. In considering the purpose of the oily matter of the skin, there
are two situations in which it deserves especial remark. 1st. Along
the edges of the eyelids, where it is poured out in considerable
quantity. Here, it is the means of confining the tears and moisture of
the eyes within the lids, defending the skin from the irritation of
that fluid, and preventing the adhesion of the lids, which is liable
to occur upon slight inflammation. 2d. In the ears, where the unctuous
wax not only preserves the membrane of the drum and the passage of the
ear moist, but also, by its bitterness, prevents the intrusion of
small insects.

654. The use of the perspiratory glands is to separate from the blood
that portion of the waste matter which is carried off through the skin
in the form of vapor. Sanctorius, a celebrated medical writer, daily,
for thirty years, weighed himself, his food, and excretions. He
estimated that _five_ of every _eight_ pounds of food and drink passed
from the system through the many outlets upon the skin. Many place the
estimate much lower. All physiologists agree that from twenty to forty
ounces of matter pass off from the skin of an adult every twenty-four
hours.

  -=-=-=-=-=-=-=-=-=-=-=-=

652. What prevents the evaporation of the water of the cuticle? Give
its 2d use. Its 3d. Its 4th. 653. What is said in reference to the
distribution of the oily matter along the edges of the eyelids? In the
ears? 654. Of what use are the perspiratory glands? How long did
Sanctorius daily weigh his food, to ascertain the amount of secretion
that passed through the skin?

  -=-=-=-=-=-=-=-=-=-=-=-=

655. The average amount of perspiration is about thirty ounces; and it
passes off in such minute portions, and mixes so rapidly with the
surrounding air, that it is not perceived. For this reason, it is
called _insensible_ perspiration. When this excretion is increased, it
forms into drops, and is called _sensible_ perspiration. The following
experiments prove the existence of this excretion from the skin.

_Experiments._ 1st. Take a cold bell-glass, or any glass vessel large
enough to admit the hand, and introduce it perfectly dry; at the same
time close the mouth by winding a napkin about the wrist; in a short
time, the insensible perspiration from the hand, will be seen
deposited on the inside of the glass. At first, the deposit is in the
form of mist; but, if the experiment be continued a sufficient time,
it will collect in drops.

2d. Hold the apparently dry hand near a looking-glass, and the
invisible vapor will soon be condensed, and cover the glass with a
slight dew.

656. It is important that this excretion be maintained with steadiness
and regularity. When the action of the perspiratory glands is
suppressed, all the vessels of the different organs will suffer
materially, and become diseased, by the redundant waste matter that
should be carried from the system. If a person is vigorous, the action
of the organs, whose functions are similar to those of the skin, as
channels for the exit of waste matter, will be increased, and thus
relieve the diseased state of the body. But the over-taxing of these
organs, to relieve the system, often produces a diseased action in
themselves.

  -=-=-=-=-=-=-=-=-=-=-=-=

What were his conclusions? 655. What is the average amount of
perspiration every twenty-four hours? What is insensible perspiration?
What is sensible perspiration? How can the existence of the excretion
of the skin be shown? Give the 2d experiment. 656. Why is it important
that these excretions be maintained regularly?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 117. 1, 1, The lines, or ridges of the cuticle, cut
perpendicularly. 2, 2, 2, 2, 2, The furrows, or wrinkles of the same. 3,
The cuticle. 4, 4, 4, The colored layer of the cuticle. 5, 5, The cutis
vera. 6, 6, 6, 6, 6, The papillæ. 7, 7, Small furrows between the
papillæ. 8, 8, 8, 8, The deeper furrows between each couple of the
papillæ. 9, 9, Cells filled with fat. 10, 10, 10, The adipose layer, with
numerous fat vesicles. 11, 11, 11, Cellular fibres of the adipose tissue.
12, Two hairs. 13, A perspiratory gland, with its spiral duct. 14,
Another perspiratory gland, with a duct less spiral. 15, 15, Oil-glands
with ducts opening into the sheath of the hair, (12.)]

_Note._--Let the pupil review the anatomy and physiology of the skin
from Fig. 117 or from anatomical outline plate No. 9.



CHAPTER XXXIII.

HYGIENE OF THE SKIN.


657. The sensibility of the skin, and the activity of the oil and
perspiratory glands, are modified by the condition of the cuticle, the
temperature of the skin and body, the purity and warmth of the air,
and the character of the light to which the body is exposed. Thus, to
maintain a healthy action of every part of this membrane, attention
should be given to _Clothing_, _Bathing_, _Light_, and _Air_.

658. CLOTHING, in itself, does not bestow heat, but is chiefly useful
in preventing the escape of heat from the body, and in defending it
from the temperature of the atmosphere. In selecting and applying
clothing to our persons, the following suggestions should be
observed.

659. _The material for clothing should be a bad conductor of heat_;
that is, it should have little tendency to conduct or remove heat from
the body. This depends mainly on the property possessed by the
material in retaining atmospheric air in its meshes.

660. _The material for clothing should not possess the property of
absorbing and retaining moisture._ Dampness, or moisture, renders
apparel a good conductor of heat; beside, if the perspired fluid, and
the saline material it holds in solution, are readily absorbed by the
clothing, they become sources of irritation to the skin with which
the apparel comes in contact.

  -=-=-=-=-=-=-=-=-=-=-=-=

657-716. Give the hygiene of the skin. 657. What influences modify the
action of the oil and perspiratory glands? To what must attention be
given to maintain a healthy action of the skin? 658. What is said in
regard to the clothing? 659. Mention a property that the material for
clothing should possess. 660. What property in the selection of
clothing should we avoid? Why?

  -=-=-=-=-=-=-=-=-=-=-=-=

661. _Furs_ contain a greater amount of air in their meshes, than any
other article, and they absorb no moisture; consequently, as an
article of dress, they are best adapted to those who are exposed to
great vicissitudes of heat and cold.

662. _Woollen cloth_ retains more air in its meshes than any other
article except furs and eider down, and it absorbs but very little
moisture. These properties, together with its comparative cheapness,
render it a good article of apparel for all classes of persons. The
only objection to its general use is, the disturbance of the
electricity of the system, and the irritation to delicate skins from
the roughness of its fibres.

_Observation._ Flannels are not only beneficial, during the cold
season, in preventing colds and rheumatism, but they are of great
utility in the warm season, in shielding the system from the chills at
evening, that induce disease of the alimentary canal. Their general
use among children and delicate females, would be a preventive of the
"season complaints" prevalent in the months of August and September.

663. _Cotton_ contains less air in its meshes than woollen, but much
more than linen. In texture, it is smoother than wool, and less liable
to irritate the skin. This fabric absorbs moisture in a small degree.
In all respects, it is well adapted for garments worn next the skin.
When woollen flannels irritate the skin, they may be lined with
cotton.

664. _Silk_ is not as good a conductor of heat as cotton, nor does it
absorb moisture to any considerable degree; its texture is smooth, and
does not irritate the skin; consequently, when the garment of this
fabric has sufficient body or thickness, it is a good article for
clothing. The greatest objection to its use is the disturbance of the
electricity of the system, and its high price.

  -=-=-=-=-=-=-=-=-=-=-=-=

661. Give the properties of fur. As an article of dress, to whom are
they best adapted? 662. Give the properties of woollen cloth. Is this
a good article for clothing? What objection? What are the advantages
of wearing flannels? 663. What are the qualities of cotton as an
article of dress? 664. Of silk?

  -=-=-=-=-=-=-=-=-=-=-=-=

665. _Linen_ is not only a good conductor of heat, and consequently
a poor article of apparel, but it likewise absorbs the fluids
carried from the system by the agency of the oil and perspiratory
glands. When garments are made of this material, the body is not
surrounded by a layer of air, but by one of moisture. This still
further increases its power to conduct heat from the system,
rendering it a very objectionable article of apparel, even in warm
weather and in hot climates, where the dress is usually thin.

666. _Clothing differs in its power of radiating heat._ This is
influenced by the color; those articles that radiate heat freely also
absorb it readily. A black surface is a good radiator, while a white
surface is not, because it reflects the calorific rays. It is obvious
that those colors which render the transmission of external heat
difficult, must impede the transmission of caloric from the body. Thus
it is manifest, that light-colored apparel is best adapted for every
season and every climate.

_Observation._ Coach-drivers are practically aware, that in cold
weather, light-colored over-coats are warmest, except when they are
exposed to the direct rays of the sun, or when seated before a
warm fire. On the other hand, when the temperature is elevated,
light-colored apparel is coolest, because the sun's rays are then
reflected.

667. _The clothing should be of a porous character._ The skin is not
only an important agent in separating from the blood those impurities
that otherwise would oppress the system and occasion death, but it
exercises great influence upon the system, by receiving oxygen through
its tissues, and giving back carbonic acid in return. Consequently,
the apparel should be made of a material that will permit free
transpiration from the skin, and likewise convey the excreted fluids
from the surface.

  -=-=-=-=-=-=-=-=-=-=-=-=

665. What is said of linen as an article of apparel? 666. Why is
light-colored apparel best adapted for every season? What is said of
the apparel of coach-drivers? 667. Why should we wear porous
clothing?

  -=-=-=-=-=-=-=-=-=-=-=-=

668. The necessity for this is illustrated in wearing India rubber
over-shoes. If they are worn over boots ten or twelve hours, not only
the hose, but the boots will be moist from retained perspiration, and
the residual matter left in contact with the skin may be reconveyed
into the system by absorption, causing headache and other diseases.
Cotton and woollen fabrics are not only bad conductors of heat, but
are also porous; for these reasons, they are well adapted to transmit
the excretions of the skin.

669. _The clothing should be not only porous, but fitted loosely._ The
garments should retain a layer of air between them and the body. Every
one is practically aware that a loose dress is much warmer than one
which fits closely; that a loose glove is warmer than a tight one; and
that a loose boot or shoe affords greater warmth than one of smaller
dimensions. The explanation is obvious; the loose dress encloses a
thin layer of air, which the tight dress is incapable of doing; and
what is required, is, that the dress should be closed at the upper
part, to prevent the dispersion of the warm air, by the ventilating
current which would be established from below.

_Observation._ As the purpose of additional garments is to maintain a
series of strata of warm air within our clothing, we should, in going
from a warm room into the cold air, put on our defensive coverings
some little time previous, in order that the layers of air which we
carry with us may be sufficiently warmed by the heat of the room, and
not borrowed from the body on exposure to the cold.

  -=-=-=-=-=-=-=-=-=-=-=-=

668. How is the necessity of porous clothing illustrated? 669. Why
should we wear loose garments? What is the use of additional garments
when going from a warm to a cold air? When should they be put on?

  -=-=-=-=-=-=-=-=-=-=-=-=

670. _The clothing should be suited to the temperature of the
atmosphere and the condition of the individual._ The invariable rule
should be, to wear enough to maintain an equal and healthy action of
the skin. Care should be taken, however, that the action of the
cutaneous vessels is not inordinately increased, as this would
debilitate, not only the skin, but the internal organs of the system,
as the stomach and lungs.

671. No rule as to the quantity of clothing can be given, as the
demand will vary with different individuals. The following are among
the most prominent causes of this variation: Those persons who have
large, active brains, full chests, well developed lungs, breathe an
adequate amount of pure air, and take sufficient food to supply the
wants of the system, require less clothing than those of an opposite
character, because more heat is generated in the system.

672. _The child and the aged person require more clothing than the
vigorous adult._ "Should we judge from observation, the inference
would be, that children require less clothing than adults. This is an
error, for the temperature in infancy is not only lower than in
manhood, but the power of creating heat is feebler. The same remarks
are applicable to those persons who have outlived the energies of
adult life."

_Observation._ The system of "hardening" children, by an inadequate
supply of clothing, and keeping them uncomfortably cold throughout the
whole day, is inhuman, as well as unprofitable. It operates upon the
child somewhat like the long-continued chill upon a certain portion of
the farmer's herd, that are kept shivering under the thatched shed,
retarding the growth of their systems, which require more food to
satisfy the keen cravings of hunger than when they are comfortably
sheltered. To make the boy robust and active, he must have nutritious
food at stated hours, and free exercise in the open air, and his
system must be guarded from chills by a due amount of apparel.

  -=-=-=-=-=-=-=-=-=-=-=-=

670. What should be the invariable rule in reference to the amount of
clothing that should be worn? What precaution should be observed? 671.
What are some of the causes of the variation of the demand for
clothing? 672. Why do the child and aged person require more clothing
than the vigorous adult? What is said of the system of hardening
children?

  -=-=-=-=-=-=-=-=-=-=-=-=

673. _More clothing is needed when a vital organ is diseased._ It may
be observed that in consumption, dyspepsia, and even in headache, the
skin is pale and the extremities cold, because less heat is generated.
Thus persons affected with these complaints, when exposed to cold air,
need more clothing than those individuals whose organs are not
diseased, and the functions of which are properly performed.

674. _More clothing is required in the evening, than during the day._
In the evening we have less vital energy, and therefore less heat is
generated in the system, than in the early part of the day; beside,
the atmosphere is damp, the skin has become moist from free
perspiration, and heat, in consequence, is rapidly removed from the
system. For this reason, when returning from crowded assemblies, we
should be provided with an extra garment.

_Observations._ 1st. If there is a chill upon the system after having
arrived home, warmth should be restored as speedily as possible. This
can be done by friction with warm flannels, and by using the warm or
vapor bath. By this procedure, the pernicious effects of the chill
will be prevented before any disease is fixed upon the system. Is it
not the duty of the parent and the guardian to learn these facts, and
to see that they are not only learned, but reduced to practice?

2d. The farmer and industrious mechanic would be freed from many a
rheumatic pain, if, while resting from their labors at evening, or
taking the ordinary meal after hard toil, they would put on an extra
garment. The coat might not feel so agreeable for the first few
minutes, but it would ultimately conduce to health and longevity.

  -=-=-=-=-=-=-=-=-=-=-=-=

673. Why do dyspeptic and consumptive persons require more clothing
than those who have healthy vital organs? 674. Why do we need more
clothing in the evening than during the day? How can the pernicious
effects of a chill be prevented? Give the 2d observation.

  -=-=-=-=-=-=-=-=-=-=-=-=

675. _The person of active habits requires less clothing than one of
sedentary employments._ Exercise increases the circulation of the
blood, which is always attended by the disengagement of a greater
quantity of heat; consequently, an increase of warmth is felt
throughout the system. We likewise need more clothing while riding,
than when we are walking; because the exercise of the former is less
than that of the latter. The same is true when resting in the field or
shop, after laborious exercise.

_Observation._ We need a greater amount of clothing while asleep, than
during the day; as not only the action of the body, but that of the
brain, during sleep, is suspended.

676. _Less clothing is required when the cutaneous surface is clean._
A film of impurities obstructs the perspiratory ducts, and diminishes
the action of their glands; consequently, less heat is generated. For
this reason, the hands or feet when clean are less liable to become
chilled or frozen.

677. _The sensitiveness of the skin to the influence of cold, is much
modified by habit._ A person who has been habituated to the
temperature of a warm room, or warm climate, suffers more when exposed
to cold, than an individual who has been accustomed to colder air.
Thus a person who labors or studies in a warm room, should wear more
clothing when exposed to the air, while walking or riding, than an
individual who labors in a cooler atmosphere. Not only is the
sensibility of the skin increased by a warm atmosphere, but the
activity of the digestive, respiratory, and nervous systems, in
generating heat, is much diminished. This is an additional reason why
an increased amount of clothing is demanded during exposure to cold
air. In all cases where practicable the heat of the system should be
maintained by exercise, in preference to the use of fur or flannel.

  -=-=-=-=-=-=-=-=-=-=-=-=

675. Why does the person of active habits require less clothing than
one of sedentary employments? 676. Why do we need less clothing when
the skin is clean? 677. Show the effect of habit on the sensitiveness
of the skin.

  -=-=-=-=-=-=-=-=-=-=-=-=

678. _Those parts of the skin usually covered, uniformly need that
protection._ The power of generating heat is diminished, and the
impressibility to cold is increased, on those portions of the skin
usually clothed. If a person wears the dress high and close about the
neck, he suffers from exposure to a cold atmosphere if a dress is worn
that is not as high or more open. As a general rule, it is preferable
that those parts of the system, as the larynx, be exposed that are not
uniformly protected by clothing.

679. _The clothing should be kept clean._ No article of apparel is
entirely free from absorption; even wool and cotton possess it in a
small degree. They take up a portion of the transpired fluids which
contain saline and animal matter, and thus the fibres of the garments
become covered with the cutaneous excretions. We are practically aware
of the retention of these secretions from the soiled appearance of
those garments worn next the skin, which are so covered as to preclude
the particles of dust from lodging upon them.

680. The porosity of the clothing is lessened when soiled, and its
power of conducting heat from the system in consequence, is increased.
The residual matter with which the clothing is coated is brought in
contact with the skin, which causes irritation, and not unfrequently
re-absorption of the elements, thrown off from the system through this
avenue. Hence warmth, cleanliness, and health require that the
clothing, particularly the garments worn next to the skin, should be
frequently and thoroughly washed. This should not be forgotten in
regard to children, for their blood circulates with greater rapidity
than that of adults, and a proportionably greater amount of waste
matter is thrown off from their systems.

681. _The under-garments worn during the day should not be worn at
night, or the reverse._ When under-garments are worn several
successive days or nights, they should not be put in drawers, or hung
up in a close closet, as soon as taken from the body, but should be
exposed to a current of air.

682. _Occupied beds should be thoroughly aired in the morning._ The
excretions from the skin are most abundant during the hours of
sleep; and if the sheets and blankets, together with the bed, are
not aired every morning, by being so arranged that both surfaces
may be exposed to the air, the materials eliminated from the skin will
be retained in the meshes of the bed-clothing, and may be conveyed
into the system of the next occupant, by absorption. Oftentimes
diseases of a disagreeable nature are contracted in this way. This
fact should be instilled into every mother's and daughter's mind.

_Observation._ Bed-linen should not be put on a bed when it is not
sufficiently dried, or contains moisture from the excretions of the
skin, nor should beds or bedding be slept in, that have remained in a
damp room that has not been occupied for many weeks, unless the
dampness is removed from the bed-linen by a warming-pan, or in some
other way.

683. _Changes of dress, from thick to thin, should always be made in
the morning._ At this time the vital powers are usually in full play.
Many a young lady has laid the foundation of a fatal disease, by
disregarding this rule, in exchanging the thick dress, with woollen
stockings, for the flimsy dress and hose of silk or cotton, which are
considered suitable for the ball-room or party. Sudden changes in
wearing-apparel, as well as in food and general habits, are attended
with hazard; and this is proportionate to the weakness or exhaustion
of the system when the change is made.

  -=-=-=-=-=-=-=-=-=-=-=-=

681. Should the garments worn during the day be worn at night? 682.
What is said respecting the cleanliness of beds and bedding? Why
should not bed-linen that is damp be slept in? 683. When should change
of dress from thick to thin be made? Why?

  -=-=-=-=-=-=-=-=-=-=-=-=

684. _When the clothing has become wet, it is best to change it
immediately._ The skin should then be rubbed with a dry crash towel,
until reaction, indicated by redness, is produced. If the garments are
not changed, the person should exercise moderately, so that sufficient
heat may continue to be generated in the system to dry the clothing
and skin without a chill. Sitting in a cool shade, or current of air,
should, by all means, be avoided; as colds are not contracted by free
and excessive exercise, but by injudicious management after such
exercise.

_Observation._ When an individual has been thrown into a profuse
perspiration by violent exercise, though the skin and clothing may
become wet, he feels no inconvenience from the dampness, as long as he
continues that amount of exercise for the reason that the circulation
of the blood being increased heat is generated in sufficient quantity
to replace the amount abstracted from the system in evaporating the
free perspiration; but as soon as the exercise is discontinued, the
increased circulation subsides, and with it the extra amount of
generated heat. This accounts for the chill we experience, when the
damp clothing is permitted to dry on the body, after the cessation of
exercise.

  -=-=-=-=-=-=-=-=-=-=-=-=

684. What suggestion when the clothing has become wet? What should be
done if the garments are not changed? What causes the chill that is
experienced when damp clothing is permitted to dry on the body?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXXIV.

HYGIENE OF THE SKIN, CONTINUED.


685. Bathing, its necessity and expediency, is obvious from the
structure and the functions of the skin. The cuticle is cast off in
minute, powdery scales, many of which are retained upon the surface by
the pressure of clothing. These mingle with the oily and saline
products of the skin, and form a thin crust. This crust, on account of
its adhesiveness, collects particles of dust and soot from the
atmosphere, and particles of foreign matter from our dress; so that in
the course of the day the whole body becomes coated with impurities.
If this coating remains, becomes thick and established upon the skin,
it will produce the following effects:--

686. 1st. _The pores will be obstructed, consequently transpiration
impeded, and the influence of the skin as an excretory entirely
prevented._ When the pores are obstructed, and transpiration is
checked, the elements of the transpired fluids will necessarily be
retained in the system; and, as they are injurious and poisonous if
retained, they must be removed by those organs whose functions in the
animal economy are similar, as the lungs, kidneys, liver, intestines,
&c.

687. When these organs are called upon to perform their offices, and
in addition that of another, the healthy equilibrium is destroyed, and
the oppressed organ will suffer from exhaustion, and become the prey
of disease. Thus, obviously, habits of uncleanliness are a cause of
consumption and other serious diseases of the vital organs. Again,
obstruction of the pores will prevent respiration through the skin,
thus depriving the blood of one source of its oxygen, and one outlet
of its carbonic acid, which will diminish the temperature of the
system, and the same results follow as when the clothing is
inadequate.

  -=-=-=-=-=-=-=-=-=-=-=-=

685. Show the necessity for bathing. 686. What effect upon the body if
the pores of the skin are obstructed? 687. What is the effect when an
organ not only performs its own specific function, but that of
another?

  -=-=-=-=-=-=-=-=-=-=-=-=

688. 2d. _The retained perspirable matter will irritate the skin, both
mechanically and chemically_; and this membrane will be kept damp and
cold, from attraction and detention of moisture; and foreign material,
as before adverted to, once removed from the system, may be reconveyed
into it by absorption. As a consequence, cutaneous eruptions and
diseases will be produced, and the re-absorption of matter once
separated from the system, will be the exciting cause of other
injurious disorders.

689. 3d. _A film of foreign substance on the skin will inevitably
become the seat of detention of miasmata and infectious vapors._ These
will remain until absorbed, and engender the diseases of which they
are the peculiar cause. This is one reason why filthy persons contract
infectious diseases more frequently than individuals of cleanly
habits.

690. _Bathing is useful to promote cleanliness._ In this capacity, it
enables us to remove the coating of impurities from the exterior of
our persons. It effects this purpose by dissolving saline matters, and
holding in temporary suspension those substances which are insoluble.

691. The cuticle is composed of a substance resembling the dried white
of egg, or, in a word, _albumen_. This is soluble in alkalies, and
these are the agents which are commonly employed for purifying the
skin. Soap is a compound of the alkali soda with oil, the former being
in excess. When used for washing, the excess of alkali combining with
the oily fluid, with which the skin is naturally bedewed, removes it,
in the form of an emulsion, and with it a portion of any adhering
matter. Another portion of the alkali softens and dissolves the
superficial layer of the cuticle; and when this is removed the cuticle
is free from impurities.

  -=-=-=-=-=-=-=-=-=-=-=-=

688. How are cutaneous eruptions frequently produced? 689. How are
infectious vapors transmitted to the system? 690. How does bathing
promote cleanliness? 691. Why is it necessary to use soap in bathing?

  -=-=-=-=-=-=-=-=-=-=-=-=

692. Every washing of the skin with soap removes the old face of the
cuticle, and leaves a new one; and were the process repeated to
excess, the latter would become so thin as to render the body sensible
to impressions too slight to be felt through its ordinary thickness.
On the other hand, when the cuticle and its accumulated impurities are
rarely disturbed, the sensitiveness of the skin is impaired. The
proper inference to be drawn from the preceding remarks, is in favor
of the _moderate_ use of soap to cleanse the skin.

_Observation._ If any unpleasant sensations are felt after the use of
soap, they may be immediately removed by washing the surface with
water slightly acidulated with lemon juice or vinegar, which
neutralizes the alkali that may remain on the skin. This is effective
treatment for "chapped hands."

693. _Bathing may be partial or general, and the water used may be
cold, temperate, tepid, warm, or hot._ A person may apply it to his
system with a sponge, it may be poured upon him, or he may immerse
himself in it. The simplest mode of bathing is to apply water to a
small extent of surface, by means of a wet sponge, and after being
wiped dry, again cover with the dress. In this way the whole body may
be speedily subjected to the influence of water, and to no less useful
friction. The water used may be warm or cold. This species of bathing
may be practised by any invalid, and always with benefit, if the
bathing is succeeded by a glow of warmth over the surface; and this is
the test by which the benefit of all forms of bathing is to be
estimated.

  -=-=-=-=-=-=-=-=-=-=-=-=

692. Why should only a moderate amount of soap be used in bathing? If
unpleasant sensations are felt from too free use of soap, how can they
be counteracted? 693. Give the different forms of bathing. What is the
simplest mode of bathing? Can this mode be adopted by invalids with
safety?

  -=-=-=-=-=-=-=-=-=-=-=-=

694. When the heat of the system is adequate, the bather may stand or
sit in a shallow tub, while he receives the water from a sponge
squeezed over the shoulders or against the body. In this form of
bathing, the person is more exposed to the cold air, and on this
account it is less suitable for very feeble individuals than the
first-mentioned method. In the early use of this form of the
sponge-bath, the bather should content himself with a single affusion
from the sponge; the body should be quickly wiped with a soft towel,
and friction applied with a crash towel or a brush.

695. The third kind of bathing is that of the shower-bath, which
provides a greater amount of affusion than the former, combined with a
greater shock to the nervous system. The concussion of the skin by the
fall of water, particularly distinguishes this from the previous modes
of bathing. The degree of concussion is modified by the size of the
openings through which the water issues, and the height of the
reservoir. The shower-bath admits of modification, adapting it to the
most delicate as well as the robust. The extent of fall, the size of
the apertures, the quantity and temperature of the water, may be
regulated at pleasure.

_Observation._ In using the shower-bath, it would be judicious to
commence with warm or tepid water, for which, by a gradual process,
cold water may be substituted. In this way the system may be inured to
cold water. After bathing, the skin should be wiped dry and rubbed
briskly.

696. The fourth form of bathing is that in which the body, or a
portion of it, is immersed in water. The temperature of water in this
form of bathing may be modified according to the sensations and
purposes of the bather. This form of bathing is designated according
to the heat of the water. When the temperature is below 75°, it is
termed a cold bath; when from 75° to 85°, a temperate bath; from 85°
to 95°, a tepid bath; from 95° to 98°, a warm bath; from 98° to 105°,
a hot bath. In using this form of bathing, the skin should be wiped
perfectly dry, and briskly rubbed.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is the test by which to estimate, the benefit of all modes of
bathing? 694. Give another method of sponge-bathing. 695. What is said
of the shower-bath? What caution is given? 696. Give the fourth form
of bathing.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ The length of time a person may remain in a cold bath
with benefit varies from two to ten minutes; while a person may remain
in a temperate, tepid, or warm bath, from ten to thirty minutes, or
until special indications are exhibited.

697. In the vapor-bath, the vapor is not only applied to the exterior
of the system, but it is inhaled and brought in contact with every
part of the interior of the lungs. The bather is seated upon a chair,
and the vapor gradually turned on around him, until the proper
temperature (90° to 110°) is attained. The bath may be continued from
ten to thirty minutes. After leaving the bath, attention should be
given to the skin, as in other forms of bathing.

698. In order to increase and promote reaction of the skin, various
measures and processes are used, some of which are practised in, and
others after, quitting the bath. Of the former, the rubbing and
brushing the skin are the most common and important. The brisk and
efficient friction of the skin with a coarse towel and flesh-brush,
after quitting the bath, should never be omitted. This short catalogue
embraces all the appliances requisite for the purpose.

699. _Bathing promotes health by its immediate and remote physiological
effects on the system._ When the body is moistened with a sponge wet
with cold water, or when an affusion by the sponge or shower-bath is
used, the skin instantly shrinks, and the whole of its tissue
contracts. This contraction diminishes the capacity of the cutaneous
system of blood-vessels, and a portion of the blood circulating through
them is suddenly thrown upon the more internal parts of the body.
The nervous system, among others, participates in it, and is stimulated
by the afflux, and communicates its stimulus to the whole system.
This causes a more energetic action of the heart and blood-vessels, and
a consequent rush of blood back to the skin. This is the state
termed _reaction_, the first object and purpose of every form of
bathing.

  -=-=-=-=-=-=-=-=-=-=-=-=

What degree of temperature of water is termed a cold bath? A
temperate? A tepid? A warm? A hot bath? State the length of time that
a person should remain in the different baths. 697. What is said of
the vapor bath? 698. Mention the different methods for promoting
reaction of the skin.

  -=-=-=-=-=-=-=-=-=-=-=-=

700. This condition of the skin is known by the redness of the
surface, the glow, comfort, and warmth which follow the bath. The
bather should direct all his care to insure this effect. By it the
internal organs are relieved, respiration is lightened, the heart is
made to beat calm and free, the mind is clear and strong, the tone of
the muscular system is increased, the appetite is sharpened, and the
whole system feels invigorated. This is the end and aim of the bather,
and to this all his training tends. The error is, to expect the result
without the preparation.

701. In order to promote reaction, and to be efficient in preserving
health, bathing should be regular, should be commenced by degrees, and
increased by a process of training, and should not be permitted to
intrude upon hours devoted to some important function, as digestion.
It must not precede or follow too closely a meal, or severe mental or
muscular exercise, as reaction is less certain and vigorous when
important internal organs are employed, than when they are at rest.
When the vital powers are greatest, and the system most free from
exhaustion, bathing is most beneficial; hence the morning is
preferable to the evening, and the middle of the forenoon to the
middle of the afternoon, for this healthful and agreeable duty; as the
vital action of the system is most energetic in the early part of the
day.

  -=-=-=-=-=-=-=-=-=-=-=-=

699. What is the effect upon the skin when cold water is applied? What
is the first object and purpose of every form of bathing? 700. How is
this condition of the skin known? Mention the salutary effects that
this condition has on the body. 701. How should bathing be performed,
in order to be efficient in preserving health?

  -=-=-=-=-=-=-=-=-=-=-=-=

702. In regard to the frequency of bathing, the face and neck, from
their necessary exposure to the atmosphere, and the impurities which
the latter contains, should receive at least two washings in
twenty-four hours, one of which should be with soap; the feet, from
the confined nature of the coverings which are worn over them, require
at least one; the armpits, from the detention, as well as from the
peculiar properties of the secretions, at least one; and the hands and
arms, as many as seem proper. The whole person should be bathed at
least every second day, but the most perfect health of every part of
the body would be maintained, if the excretions from the skin were
removed daily.

703. In diseases of the skin and internal organs, bathing is a
remedial measure of great power. It should never be neglected or
omitted. It is not only pleasant and safe, but is really more
effective than any medicine administered internally. This, like other
curative means, should be applied by the direction and under the eye
of the medical adviser, that it may be adapted to the condition of the
patient.

704. "From the first hour of man's existence to his latest breath, in
health and in sickness, rich or poor, water is always requisite. Baths
were dedicated by the ancients to the divinities of medicine,
strength, and wisdom, namely, Æsculapius, Hercules, and Minerva, to
whom might properly be added the goddess of health, Hygeia. The use of
water has been enforced as a religious observance, and water has been
adopted as one of the symbols of Christianity."

  -=-=-=-=-=-=-=-=-=-=-=-=

When should bathing be performed? 702. How often should we bathe? 703.
What is said of bathing in disease? Who should direct the kind of bath
proper in different diseases? 704. Were baths dedicated by the
ancients?

  -=-=-=-=-=-=-=-=-=-=-=-=

705. The AIR is an agent of importance in the functions of the skin.
It imparts to this membrane oxygen, and receives from it carbonic
acid. It likewise removes from it a large portion of the perspiration
and the more fluid portions of the oily secretion. In order that the
air may accomplish these ends, it is necessary that it come in contact
with the body. This is one of the many reasons why we should wear
loose and porous clothing.

706. Again, the air should be pure, and free from redundant moisture.
In the warm mornings of July and August, the air is loaded with
moisture and impurities, and the perspirable matter is not removed
from the system as it is when the air is pure and dry. This is the
cause of the general lassitude that is experienced during such
mornings. As soon as the fog is dispelled, these unpleasant sensations
are removed. To sustain the functions of the skin in a healthy state,
the parlor, kitchen, sleeping-room, school-house, and work-shop,
should be well ventilated. The blood of the system will be purer, and
its color of a brighter scarlet, if the skin is surrounded by fresh
and pure air, than when it is foul or moist.

707. The LIGHT permeating the skin, not only exercises a salutary
influence upon this membrane, but upon the blood, and, through this
fluid, upon the whole system. For this reason, the kitchen and the
sitting-room, which are the apartments most used by ladies, should be
selected from the most pleasant and well-lighted rooms in the house.
On the other hand, dark rooms and damp cellar-kitchens should be
avoided, as exercising an injurious influence upon both body and
mind.

708. The dark, damp rooms, so much used in cities and large
villages, by indigent families and domestics, are fruitful causes
of disease, as well as of vice, poverty, and suffering. Common
observation shows that solar light also exercises much influence
upon the vigor and color of vegetables. Plants that are kept in
well-lighted rooms, have darker and more brilliant colors than
those that grow in darkened apartments.

  -=-=-=-=-=-=-=-=-=-=-=-=

705. Give the reasons why pure air should be supplied to the skin.
706. What is the cause of the general lassitude in a damp, warm
morning? 707. Show the salutary effects of light on the skin. 708.
What is one cause of disease and suffering in large villages?

  -=-=-=-=-=-=-=-=-=-=-=-=

709. BURNS and SCALDS are terms applied to those conditions of the
skin which are produced by the application of an undue amount of heat,
which changes the action of its vessels.

710. A small degree of heat will irritate the nerves, and cause an
increased action of the blood-vessels. This is attended with severe
smarting pain, and will be followed by the deposition of serum under
the cuticle, unless applications are made immediately, to prevent
vesication, or blistering. To prevent or suppress this state of
arterial action, wet some folds of cotton or woollen cloth with cold
water, and apply them to the parts scalded; continue to apply cold
water, so as to steadily maintain the low temperature of the
applications, as long as the _smarting pain_ is experienced. The
steady application of cold dressing also tends to prevent an increased
action of the blood-vessels, and will suppress it, if it already
exist.

711. When blisters are formed, the cuticle is separated from the other
tissues of the skin by the effusion of serum. In all cases, if this
layer of the skin is not removed, a small opening should be made in
the raised cuticle, by which the serum deposited may be removed. Under
such circumstances, never remove the cuticle, as it makes the best
possible covering for the blood-vessels and nerves of the true skin.
The cold water dressing, recommended in the preceding paragraph, may
then be applied as long as the smarting sensation continues. After the
pain has subsided, the blistered part may be covered by a patch of
cotton or linen cloth, upon which an ointment, made of lard and
bees-wax, has been spread.

  -=-=-=-=-=-=-=-=-=-=-=-=

709. To what condition of the skin are the terms burns and scalds
applied? 710. What is the effect when only a small degree of heat is
applied to the skin? How can vesication be prevented? 711. What should
be the treatment when blisters are formed?

  -=-=-=-=-=-=-=-=-=-=-=-=

712. If the cuticle has been removed, there will be much suffering,
because the nerves are unduly stimulated by the air. The cuticle is
the sheath or covering of the vessels and nerves of the skin, and when
it is removed, a substitute should be applied. This substitute should
be soothing, and cover the denuded surface. Linseed-meal or ground
slippery-elm bark poultice, fresh cream, or lard and bees-wax, spread
upon linen or cotton cloth, would make a good dressing. When dressings
are applied, they should not be removed until they become dry and
irritating.

713. If there is much suffering, administer to an adult from
twenty-five to sixty drops of laudanum, according to the severity of
the pain. If the patient is a child, from fifteen drops to a
tea-spoonful of paregoric may be administered. When there is much
prostration, some hot peppermint tea or other stimulant may be found
necessary to bring on reaction.

714. The hands, feet, ears, &c., are subject, in cold latitudes, to be
_frozen_, or _frost-bitten_. This may occur when the patient, at the
moment, is not aware of it. The part affected at first assumes a dull
red color, which gradually gives place to a pale, waxy appearance, and
becomes quite insensible. The first thing to be done in such cases, is
to reëstablish circulation. This should be effected very gradually. If
a large quantity of blood is thrown suddenly into the chilled and
debilitated vessels of the frozen part, inflammation may be produced
that will destroy the vitality of the limb.

  -=-=-=-=-=-=-=-=-=-=-=-=

712. That should be the treatment if the cuticle has been removed? How
often should the dressing of burns be removed? 713. What may be
necessary when there is much suffering? 714. What is the appearance of
limbs while freezing? How should the circulation be at first
reëstablished? What should be avoided?

  -=-=-=-=-=-=-=-=-=-=-=-=

715. The circulation and sensibility may be restored by rubbing the
frozen limb, with snow, or, when this is not to be obtained, cold
water; but snow is always to be preferred. The fire should be avoided;
and it would be better for the patient to be kept in a cold room, for
a time, where there is no fire, or where the temperature is moderate.

716. When a person is found benumbed with cold, and almost or quite
insensible, he should be taken into a cold room, the clothing removed,
and friction commenced and continued for some time, with _snow_. When
warmth begins to be restored, the individual should be rubbed with dry
flannel, and the friction continued until reaction takes place.

_Observation._ When the toes and heels have been repeatedly chilled,
there may be produced a disease called _chilblains_. This affection is
attended with tenderness of the parts, accompanied with a peculiar and
troublesome itching. The prevention of this disease is in wearing warm
hose and thick shoes of ample size. Bathing the feet morning and
evening is also a prevention of this disagreeable affection. When
chilblains exist, apply cold water, warm camphorated spirits, or
turpentine linament.

  -=-=-=-=-=-=-=-=-=-=-=-=

715. How may the circulation and sensibility be restored? 716. What
treatment should be adopted when a person is benumbed with cold? What
treatment should be adopted when warmth begins to be restored? What is
said of chilblains?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXXV.

APPENDAGES OF THE SKIN.


717. The HAIRS are appendages of the skin, and, like the cuticle, they
are a product of secretion. They have no blood-vessels or nerves, and,
consequently, no vitality. The hairs take their origin from the
cellular membrane, in the form of bulbs. Each hair is enclosed beneath
the surface by a vascular secretory follicle, which regulates its form
during growth. In texture, it is dense, and homogeneous toward the
circumference, and porous and cellular in the centre, like the pith of
a plant. Every hair has on its surface pointed barbs, arranged in a
spiral manner, and directed toward the root of the hair; so that, if a
hair be rolled between the fingers, it moves only in one direction.

[Illustration: Fig. 118. The hair follicle (1) is represented as imbedded
in the cellular membrane, (2,) which is situated beneath the skin. 3, 3,
The membranous sac, which has a narrow neck, opening externally by a
contracted orifice, through which the hair (4) passes. Its internal
surface is smooth, and not adherent to the hair, but separated from it by
a reddish fluid. From the bottom of the sac (5) the pulp of the hair
arises, and passes through the skin at 6.]

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717-723. _Describe the appendages of the skin._ 717. Why have not
hairs vitality? Where do they take their origin? Give their structure.
What is represented by fig. 118?

  -=-=-=-=-=-=-=-=-=-=-=-=

718. The color of the hair varies in different individuals, and is
generally supposed to depend on the fluids contained in the pith.
There are two causes which act in changing the hair gray. The first
is, defective secretion of the coloring fluid. The second is, the
canals, which convey the fluid into the hair, become obliterated. In
the first instance, the hair will remain; in the second, it dies, and
drops out; the cuticle of the scalp grows over the canal, which is
soon obliterated, and the head becomes bald.

_Observation._ It is related that the hair of Marie Antoinette, Queen
of France, and others, from excessive mental agitation, changed from
black to gray in a single night. This is not strictly true; the
secretion may be arrested, but that already deposited in the pith will
require days or weeks to be removed.

719. Upon the upper part of the head, the oil-tubes open into the
hair-sacs; consequently, the secretion of the oil-glands is spread
over the surface of the hair, and not upon the cuticle. This is the
cause of the dry, white, branny scales, called "scurf," or "dandruff,"
upon the head. This is natural, and cannot be prevented. When scurf
exists, the only necessary application to remove it, is the frequent
use of the hair-brush, and washing with pure water.

_Observation._ The secretion of the oil-glands may become impacted
around the hairs as they issue from the skin, and thus prevent their
outward movement in growing. The pressure of the matter deposited at
their bulbs will then cause itching. The comb and the brush may be
used to remove the impacted matter, and relieve the disagreeable
sensation.

720. The oil is most abundant near the roots of the hair A free use
of the brush spreads it along the hairs, and gives them a smooth,
glossy appearance. Soap should rarely be used in washing the head, as
it will remove the oil which is essential to the health and appearance
of the hair.

  -=-=-=-=-=-=-=-=-=-=-=-=

718. Upon what does the color of the hair depend? What are the causes
of the hair becoming gray? What is the cause of the hair dropping out?
What is related of Marie Antoinette? 719. How is "dandruff" on the
scalp produced? What is the only necessary application to remove it?
Give observation. 720. Where is the oil of the hair most abundant?

  -=-=-=-=-=-=-=-=-=-=-=-=

721. The uses of the hair vary in different regions of the body. Upon
the head, it aids in shielding the brain from injury by blows, and it
likewise serves to protect this part of the system from heat and cold,
thus maintaining equal temperature of the cerebral organ. About the
flections of the joints, as in the axilla, (armpit,) they prevent
irritation of the skin from friction; in the passages to the ears and
nostrils, they present an obstacle to the ingress of insects and
foreign bodies; while in the eyebrows and eyelids, they serve to
protect the organ of vision.

[Illustration: Fig. 119. A section of the end of the finger and nail. 4,
Section of the last bone of the finger. 5, Fat, forming the cushion at
the end of the finger. 2, The nail. 1, 1, The cuticle continued under and
around the root of the nail, at 3, 3, 3.]

722. The NAILS are hard, elastic, flexible, semi-transparent scales,
and present the appearance of a layer of horn. The nail is divided
into the _root_, the _body_, and the _free portion_. The root is that
part which is covered on both surfaces; the body is that portion which
has one surface free; the free portion projects beyond the end of the
finger.

723. The nail is formed of several laminæ, or plates, that are fitted
the one to the other; the deepest is that which is last formed. The
nails, as well as the hoofs of animals and the cuticle, are products
of secretion. They receive no blood-vessels or nerves. If the cuticle
be removed in severe scalds they will separate with it, as the hoofs
of animals are removed by the agency of hot water. The nails increase
in length and thickness, by the deposition of albumen upon their under
surface, and at their roots, in a manner similar to the growth of the
cuticle, of which they constitute a part.

  -=-=-=-=-=-=-=-=-=-=-=-=

How can it be spread along the hairs? Why should soap not be used in
washing the hair? 721. Of what use is the hair upon the head? About
the flexions of the joints? In the nasal and ear passages? Upon the
eyebrows and eyelids? 722. Describe the nails. 723. How are they
formed?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observations._ 1st. The nail upon its under surface is fashioned into
thin vertical plates, which are received between the folds of the
sensitive skin. In this manner, the two kinds of laminæ reciprocally
embrace each other, and the firmness of connection of the nail is
maintained. If we look on the surface of the nail, we see an
indication of this structure in the alternate red and white lines
which are there observed. The former of these correspond with the
sensitive laminæ; the latter with the horny plates. The ribbed
appearance of the nail is due to the same circumstance. These
sensitive laminæ are provided with an unusual number of capillary
vessels for the formation of the nail, and hence they give a red tint
to the portion under which they lie.

2d. Near the root of the nail there is a part that is not laminated,
and it is less abundantly supplied with blood-vessels. This portion
consequently looks pale compared with the laminated portion, and from
its half-moon shape is technically termed _lunula_. Beyond the lunula,
the root of the nail is imbedded in the fold of the sensitive skin,
and has the same relation to that structure that any single one of the
thin horny plates of its under surface has to its corresponding pair
of sensitive laminæ.

724. The nails, from their position, are continually receiving
knocks, which produce a momentary disturbance of their cell
formation, followed by a white spot. The care of the nails should
be strictly limited to the knife or scissors, to their free border,
and an ivory presser, to prevent adhesion of the free margin of the
scarf-skin to the surface of the nail. This edge of the cuticle
should never be pared, the surface of the nail never scraped, nor the
nails cleaned with any instrument whatever, except the nail-brush,
aided by water and soap. An observance of these suggestions, will
prevent irregularities and disorders of the nails.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give observation 1st. Observation 2d. 724. How should the nails be
treated to prevent irregularities and disease?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observations._ 1st. When we wear a shoe that is too short for the
foot, the edge of the nail is brought against the leather. This
interrupts the forward growth of the nail, and it spreads out on the
sides, and becomes unusually thick. It then presses upon the soft
parts, and is said to "grow into the flesh." The prevention is, to
wear shoes of ample size.

2d. Instances are by no means unfrequent in which the power of
production of the nail at the root becomes entirely destroyed, and it
then grows in thickness only. When this affection occurs, it is often
remarkable what a mass the nail presents. Instances are on record,
where the nail is regularly shed; and, whenever the old nail falls
off, a new one is found beneath it, perfectly formed. Sometimes the
growth in length is not entirely checked, although growth in thickness
is induced; the nail then presents a peculiar appearance.

  -=-=-=-=-=-=-=-=-=-=-=-=

What causes the edge of the nail "to grow into the flesh" of the toe?
How prevented?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXXVI.

THE NERVOUS SYSTEM.


725. In the preceding chapters, we have seen how various and complex
are many of the motions necessary to maintain the life of an animal
whose organization is superior to all others. We have noted the
wonderful mechanism of the muscular system, in producing the varied
movements of the body, the different processes by which the food is
converted into chyle and mixed with the blood, and the circulation of
this fluid to every organ and tissue of the system, that each may
select from it the very principles which it requires for its growth.

726. Lymphatic absorption commences as soon as nutrition is completed,
and conveys the useless, worn-out particles of different tissues back
into the circulating fluid; while the respiratory organs and secretory
glands perform the work of preparing the waste products to be
eliminated from the body. Each of these processes effects a single
object, and is performed in a regular manner.

727. "They must succeed each other in proper order in propelling every
particle to its proper destination, or life would be sacrificed almost
at the moment of its commencement. There is, therefore, a mutual
dependence of all portions of the machinery of organic life upon each
other, and a necessity for some medium of communication from one organ
to another, by which they may convey mutual information of their
several conditions, if we may be permitted to employ a figurative
expression. Were there no such medium, how would the stomach notify
the heart that additional exertion on its part is required, because
the stomach is busy in digesting food?

  -=-=-=-=-=-=-=-=-=-=-=-=

725. What has been noted in the preceding chapters? 726. Show the
manner in which the several processes are performed. 727. How must
they succeed each other?

  -=-=-=-=-=-=-=-=-=-=-=-=

728. "When we are exerting the muscular system for a long time in some
laborious employment, how else are our members to inform the stomach
that they are too much occupied with their duties to spare the blood
necessary in digestion; that it is requisite that the appetite
should decline; and that digestion should cease for the time, even if
the stomach should be oppressed with its contents? When we are
thinking, how else are the blood-vessels to be told that an unusual
supply of their contents is wanting in the head? or when the whole
frame is weary with exertion, how, without some regular line of
intelligence between all the organs, is the brain to be instructed
that circumstances require that it should go to sleep? To supply the
necessary medium of communication, Providence has furnished all the
animals that possess distinct organs, with a peculiar apparatus
called the _Nervous System_."


ANATOMY OF THE NERVOUS SYSTEM.

729. The NERVOUS SYSTEM consists of the _Cer´e-bro-spi´nal Cen´tre_,
and of numerous rounded and flattened white cords, called _nerves_,
which are connected at one extremity with the cerebro-spinal centre,
and at the other, distributed to all the textures of the body. The
sympathetic nerve is an exception to this description; for, instead of
one, it has many small centres, which are called _gan´gli-a_, and
which communicate very freely with the cerebro-spinal centre, and with
its nerves.

  -=-=-=-=-=-=-=-=-=-=-=-=

728. What is the medium of communication from one organ to another?
729-754. _Give the anatomy of the brain and cranial nerves._ 729. Of
what does the nervous system consist? What constitutes an exception to
this?

  -=-=-=-=-=-=-=-=-=-=-=-=

730. The CEREBRO-SPINAL CENTRE consists of two portions: The _brain_,
and the _spinal cord_. For convenience of description, the nervous
system may be divided into the _Brain_, _Cranial Nerves_, _Spinal
Cord_, _Spinal Nerves_, and the _Sympathetic Nerve_.

731. The term BRAIN designates those parts of the nervous system,
exclusive of the nerves themselves, which are contained within the
cranium, or skull-bones; they are the _Cer´e-brum_, _Cer-e-bel´lum_,
and _Me-dul´la Ob-lon-ga´ta_. These are invested and protected by the
membranes of the brain, which are called the _Du´ra Ma´ter_,
_A-rach´noid_, and _Pi´a Ma´ter_.

[Illustration: Fig. 120. 1, 1, The scalp turned down. 2, 2, 2, The cut
edge of the bones of the skull. 3, The external strong membrane of the
brain (dura mater,) suspended by a hook. 4, The left hemisphere of the
brain, showing its convolutions.]

  -=-=-=-=-=-=-=-=-=-=-=-=

730. Of what does the cerebro-spinal centre consist? How is the
nervous system divided? 731. What does the term brain designate? Name
them. How are they protected? Describe fig. 120.

  -=-=-=-=-=-=-=-=-=-=-=-=

732. The CEREBRUM IS divided into two hemispheres, by a cleft, or
fissure. Into this cleft dips a portion of the dura mater, called the
_falx cer´e-bri_, from its resembling a sickle. The apparent design of
this membrane is to relieve the one side from the pressure of the
other, when the head is reclining to either side. Upon the superior
surface of the cerebrum are seen undulating windings, called
_con-vo-lu´tions_. Upon its inferior, or lower surface, each
hemisphere admits of a division into three lobes--the anterior,
middle, and posterior. (Fig. 122, 123)

[Illustration: Fig. 121 A section of the skull-bones and cerebrum. 1, 1,
The skull. 2, 2, the dura mater 3, 3, The cineritious portion of the
cerebrum. 4, 4, The medullary portion. The dark points indicate the
position of divided blood-vessels. 5, 5, The lateral ventricles.]

  -=-=-=-=-=-=-=-=-=-=-=-=

732. How is the cerebrum divided? What is the use of the falx cerebri?
What is seen upon the superior surface of the brain? Its inferior?

  -=-=-=-=-=-=-=-=-=-=-=-=

733. When the upper part of the hemispheres is removed horizontally
with a sharp knife, a centre of white substance is brought to view.
This is surrounded by a border of gray, which follows the depressions
of the convolutions, and presents a zigzag outline. The divided
surface will be seen studded with numerous small red points, which are
produced by the escape of blood from the division of the minute
arteries and veins. The gray border is called the cortical, or
_cineritious_ portion, while the white central portion is called the
_medullary_. The two hemispheres are connected by a dense layer of
transverse fibres, called _cor´pus cal-lo´sum_.

734. In the interior of the brain there are several cavities, two of
which are of considerable size, and are called the lateral ventricles.
They extend from the anterior to the posterior part of the brain, and
wind their way into other parts of the cerebral organ.

_Observation._ In the disease called "dropsy of the brain,"
(hydrocephalus internus,) the serum, or water, is usually deposited in
these ventricles. This is effused from the many small blood-vessels of
the membrane in these cavities.

735. The brain is of a pulpy character, quite soft in infancy and
childhood; but it gradually becomes more and more consistent, and in
middle age it assumes the form of determinate structure and
arrangement. It is more abundantly supplied with blood than any organ
of the system. No lymphatics have been detected, but it is to be
presumed that they exist in this organ.

736. The CEREBELLUM is about seven times smaller than the cerebrum.
Like that organ, it is composed of white and gray matter, but the
gray constitutes the larger portion. Its surface is formed of parallel
plates separated by fissures. The white matter is so arranged, that
when cut vertically, the appearance of the trunk and branches of a
tree (_ar´bor vi´tæ_) is presented. It is situated under the posterior
lobe of the cerebrum, from which it is separated by a process of the
dura mater, called the _ten-to´ri-um_.

  -=-=-=-=-=-=-=-=-=-=-=-=

733. Describe the appearance of the brain when a horizontal section
has been made. What is the gray border often called? What connects the
hemispheres? 734. Describe the ventricles of the brain. In the disease
called "dropsy of the brain," where is the water deposited? 735. What
is the character of the brain in childhood? In adults? 736. How does
the cerebellum compare in size with the cerebrum?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 122. The under surface, or base, of the brain and
origin of the cranial nerves. 1, 1, The anterior lobes of the cerebrum.
2, 2, The middle lobes. 3, 3, The posterior lobes, almost concealed by
the cerebellum. 4, 4, The cerebellum. 7, 7, The longitudinal fissure that
divides the brain into two hemispheres. 8, The first pair of nerves. 9,
9, The second pair of nerves. 10, The decussation, or crossing, of its
fibres. 13, 13, The third pair of nerves. 14, The pons varolii. 15, 15,
The fourth pair of nerves. 16, 16, The fifth pair of nerves. 17, The
sixth pair of nerves. 18, 18, The seventh and eighth pair of nerves. 19,
The medulla oblongata, with the crossing of some of its fibres exhibited.
20, The ninth pair of nerves. 21, The tenth pair of nerves, 22, The
eleventh pair of nerves. 23, The twelfth pair of nerves.]

  -=-=-=-=-=-=-=-=-=-=-=-=

Describe this portion of the brain. Explain fig. 122.

  -=-=-=-=-=-=-=-=-=-=-=-=

737. The MEDULLA OBLONGATA, or that portion of the spinal cord which
is within the skull, consists of three pairs of bodies, (_cor´pus
py-ram-i-da´le_, _res-ti-for´me_, and _ol-i-va´re_,) united in a
single bulb.

[Illustration: Fig. 123. The base of the skull and the openings through
which the cranial nerves pass. 1, 1, The first pair of nerves. 2, 2, The
cribriform plate of the ethmoid bone through which this nerve passes. 3,
3, The second pair of nerves. 4, 4, The optic foramen in the sphenoid
bone; through which passes the second pair of nerves. 5, 5, The
sphenoidal fissure. 6, 6, The third pair of nerves. 7, 7, The fifth pair
of nerves. 8, 8, The ophthalmic branch of the fifth nerve. The third, the
ophthalmic branch of the fifth and the sixth nerve pass from the brain
through the sphenoidal fissure to the eye. 9, 9, The superior maxillary
branch of the fifth nerve. 10, 10, The foramen rotundum, (round opening,)
through which the nerve 9, 9, passes to the upper jaw. 11, 11, The
inferior maxillary branch of the fifth pair. 12, 12, The foramen ovale,
(oval opening,) through which the nerve 11, 11, passes to the lower jaw.
13, 13, The sixth pair of nerves. 14, 14, The seventh and eighth pair of
nerves. 15, 15, The opening in the temporal bone, through which the
seventh and eighth nerves pass to the face and ear. 16, 16, The ninth
pair of nerves. 17, The tenth pair of nerves. 18, 18, The eleventh pair
of nerves. 19, 19, The foramen lacerum (rough opening.) The ninth, tenth,
and eleventh nerves pass from the brain through this opening. 20, The
spinal cord. 21, The foramen spinalis, through which the spinal cord
passes. 22, 22, The position of the anterior lobe of the brain. 23, 23,
The middle lobe. 24, 24, The posterior lobe. 25, 25, A section of the
skull-bones.]

  -=-=-=-=-=-=-=-=-=-=-=-=

737. Describe the medulla oblongata. Explain fig. 123.

  -=-=-=-=-=-=-=-=-=-=-=-=

738. The DURA MATER is a firm, fibrous membrane, which is exposed on
the removal of a section of the skull-bones. This lines the interior
of the skull and spinal column, and likewise sends processes inward,
for the support and protection of the different parts of the brain. It
also sends processes externally, which form the sheaths for the
nerves, as they quit the skull and spinal column. The dura mater is
supplied with arteries and nerves.

[Illustration: Fig. 124. A vertical section of the cerebrum, cerebellum,
and medulla oblongata, showing the relation of the cranial nerves at
their origin. 1, The cerebrum. 2, The cerebellum, with its arbor vitæ
represented. 3, The medulla oblongata. 4, The spinal cord. 5, The corpus
callosum. 6, The first pair of nerves. 7, The second pair. 8, The eye. 9,
The third pair of nerves. 10, The fourth pair. 11, The fifth pair. 12,
The sixth pair. 13, The seventh pair. 14, The eighth pair. 15, The ninth
pair. 16, The tenth pair. 10, The eleventh pair. 18, The twelfth pair.
20, Spinal nerves. 21, The tentorium.]

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738. Describe the dura mater. What is its use? Explain fig. 124.

  -=-=-=-=-=-=-=-=-=-=-=-=

739. The ARACHNOID, so called from its extreme tenuity, is the serous
membrane of the brain and spinal cord, and is, like other serous
membranes, a closed sac. It envelops these organs, and is reflected
upon the inner surface of the dura mater, giving to that membrane its
serous investment.

740. The PIA MATER is a vascular membrane, composed of innumerable
vessels, held together by cellular membrane. It invests the whole
surface of the brain, and dips into its convolutions. The pia mater is
the nutrient membrane of the brain, and receives its blood from the
carotid and vertebral arteries. Its nerves are minute branches of the
sympathetic, which accompany the branches of the arteries.

741. The CRANIAL NERVES, that connect with the brain, are arranged in
twelve pairs. They are called: 1st. The _Ol-fact´o-ry_. 2d. The
_Op´tic_. 3d. The _Mo-to´res Oc-u-lo´rum_. 4th. The _Pa-thet´i-cus_.
5th. The _Tri-fa´cial_. 6th. The _Ab-du-cen´tes_. 7th. The _Por´ti-o
Du´ra_. 8th. The _Por´ti-o Mol´lis_. 9th. The _Glos´so-pha-ryn´gi-al_.
10th. The _Pneu-mo-gas´tric_. 11th. The _Spi´nal Ac´ces-so-ry_. 12th.
The _Hy´po-glos´sal_.

742. The OLFACTORY NERVE (first pair) passes from the cavity of the
skull through many small openings in a plate of the _eth´moid_ bone.
(This plate is called _crib´ri-form_, from its resemblance to a
sieve.) This nerve ramifies upon the membrane that lines the nasal
passages. It is the softest nerve of the body. (Fig. 136.)

743. The OPTIC NERVE (second pair) passes from the interior of the
cranium, through an opening in the base of the skull, (_fo-ra´men
op´ti-cum_,) to the cavity for the eye. It pierces the coats of the
eye, and expands in the retina.

744. The MOTORES OCULORUM (third pair) pass from the brain, through
an opening of the _sphe´noid_ bone, (_sphe-noid´al fis´sure_,) to the
muscles of the eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

739. Describe the arachnoid membrane. 740. What is said respecting the
pia mater? 741. How many pairs of cranial nerves? Name them. 742.
Describe the olfactory nerve. 743. The optic nerve. 744. Describe the
motores oculorum.

  -=-=-=-=-=-=-=-=-=-=-=-=

745. The PATHETICUS (fourth pair) passes from the brain, through the
sphenoidal fissure, to the superior oblique muscle of the eye.

[Illustration: Fig. 125. The distribution of the third, fourth, and sixth
pairs of nerves, to the muscles of the eye. 1, The ball of the eye and
rectus externus muscle. 2, The upper jaw. 3, The third pair, distributed
to all the muscles of the eye, except the superior oblique, and external
rectus. 4, The fourth pair passes to the superior oblique muscle. 6, The
sixth pair, is distributed to the external rectus muscle.]

746. The TRIFACIAL NERVE (fifth pair) is analogous to the spinal
nerves in its origin by two roots, from the anterior and posterior
columns of the spinal cord. It has a ganglion, like the spinal nerves
upon its posterior root. For these reasons, it ranges with the spinal
nerves, and is considered the cranial spinal nerve. This nerve divides
into three branches:--The _oph-thal´mic_, superior _max´il-la-ry_, and
inferior _max´il-la-ry_.

  -=-=-=-=-=-=-=-=-=-=-=-=

745. The patheticus. What does fig. 125 represent? 746. What is the
trifacial nerve sometimes called? Why is it classed with the cranial
spinal nerves? Give the names of its branches.

  -=-=-=-=-=-=-=-=-=-=-=-=

747. The ophthalmic nerve passes from the cranial cavity through the
sphenoidal fissure. It sends branches to the forehead, eye, and nose.
The superior maxillary nerve passes through an opening in the base of
the skull, (_foramen ro-tund´dum_,) and sends branches to the eye, the
teeth of the upper jaw, and the muscles of the face. The inferior
maxillary nerve escapes from the cranial cavity through an opening
called _foramen o-va´le_. It sends branches to the muscles of the
lower jaw, the ear, the tongue, and the teeth of the lower jaw.

[Illustration: Fig. 126. The distribution of the fifth pair of nerves. 1,
The orbit for the eye. 2, The upper jaw. 3, The tongue. 4, The lower jaw.
5, The fifth pair of nerves. 6, The first branch of this nerve, that
passes to the eye. 9, 10, 11, 12, 13, 14, Divisions of this branch. 7,
The second branch of the fifth pair of nerves is distributed to the teeth
of the upper jaw. 15, 16, 17, 18, 19, 20, Divisions of this branch. 8,
The third branch of the fifth pair, that passes to the tongue and teeth
of the lower jaw. 23. The division of this branch that passes to the
tongue, called the _gust´a-to-ry_. 24. The division that is distributed
to the teeth of the lower jaw.]

  -=-=-=-=-=-=-=-=-=-=-=-=

747. Where do the filaments of the ophthalmic branch ramify? The
superior maxillary? The inferior maxillary? Explain fig. 126.

  -=-=-=-=-=-=-=-=-=-=-=-=

748. The ABDUCENTES (sixth pair) passes through the opening by which
the carotid artery enters the cranial cavity. It is the smallest of
the cerebral nerves, and is appropriated to the external straight
muscle of the eye.

749. The PORTIO MOLLIS (seventh pair) enters the hard portion of the
_tem´po-ral_ bone at the internal auditory opening, and is distributed
upon the internal ear. (Fig. 147, 148.)

[Illustration: Fig. 127. A representation of the distribution of the
eighth pair of nerves with some branches of the fifth. 1, 2, 3, 5, 7, 9,
Are branches of the eighth pair. They are distributed over the face in a
radiated manner, which constitutes the pes anserinus, (foot of a goose.)
The nerves 4, 6, 8, are branches of the fifth pair. 10, 11, 12, 13, 14,
15, 16, Are branches of nerves from the upper part of the spinal cord,
(cervical.)]

750. The FACIAL NERVE (eighth pair) passes from the skull through an
opening situated below the ear, (_mas´toid foramen_.) It is
distributed over the face, supplying the muscles with nervous
filaments.

  -=-=-=-=-=-=-=-=-=-=-=-=

748. What is said of the abducentes, or sixth pair of nerves? 749. Of
the portio mollis? Explain fig. 127. 750. Of the facial nerve?

  -=-=-=-=-=-=-=-=-=-=-=-=

751. The GLOSSO-PHARYNGEAL NERVE (ninth pair) passes from the brain,
through an opening with the jugular vein, (_foramen lac´e-rum_.) It is
distributed to the mucous membrane of the tongue and throat, and also
to the mucous glands of the mouth.

752. the PNEUMOGASTRIC NERVE (tenth pair) escapes from the brain
through the foramen lacerum. It sends branches to the larynx, pharynx,
oesophagus, lungs, spleen, pancreas, liver, stomach, and intestines.
(Fig. 132.)

753. The SPINAL ACCESSORY NERVE (eleventh pair) has its origin in the
respiratory tract of the spinal cord. It connects with the ninth and
tenth pairs of nerves, and is distributed to the muscles about the
neck.

754. The HYPO-GLOSSAL NERVE (twelfth pair) passes from the brain,
through a small opening, (_con´dy-loid foramen_.) It ramifies upon the
muscles of the tongue, and is its motor nerve.

_Observation._ The cranial nerves, with the exception of the
olfactory, optic, and auditory, connect with each other by means of
filaments. They also send connecting nervous filaments to the upper
spinal nerves, (cervical,) and the sympathetic nerve.

  -=-=-=-=-=-=-=-=-=-=-=-=

751. Describe the glosso-pharyngeal nerve. 752. The pneumogastric
nerve. 753. The spinal accessory nerve. 754. The hypo-glossal nerve.

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXXVII.

ANATOMY OF THE NERVOUS SYSTEM, CONTINUED.


755. The spinal column contains the spinal cord, the roots of the
spinal nerves, and the membranes of the cord.

756. The SPINAL CORD extends from the medulla oblongata to the second
lumbar vertebra, where it terminates in a rounded point. It presents a
difference of diameter in different parts of its extent, and exhibits
three enlargements. The uppermost of these is the medulla oblongata.
There is no distinct demarkation between this enlargement and the
spinal cord. The next corresponds with the origin of the nerves
distributed to the upper extremities; the third enlargement is
situated near the termination of the cord, and corresponds with the
attachment of the nerves which are intended for the supply of the
lower extremities.

757. An anterior and posterior fissure divides the spinal cord into
two lateral cords. These are united by a thin layer of white
substance. The lateral cords are each divided by furrows into three
distinct sets of fibres, or columns; namely the _anterior_, _lateral_,
and _posterior_ columns. The anterior are the motor columns; the
posterior are the columns of sensation; the lateral columns are
divided in their function between motion and sensation. They contain
the fasciculus described, by Sir Charles Bell, as the respiratory
tract.

[Illustration: Fig. 128. A section of the brain and spinal column. 1, The
cerebrum. 2, The cerebellum. 3, The medulla oblongata. 4, 4, The spinal
cord in its canal.]

[Illustration: Fig. 129. Anterior view of the brain and spinal cord. 1,
1, The two hemispheres of the cerebrum. 3, 3, The cerebellum. 4, The
olfactory nerve. 5, The optic nerve. 7, The third pair of nerves. 8, The
pons varolii. 9, The fourth pair of nerves. 10, The lower portion of the
medulla oblongata. 11, 11, The spinal cord. 12, 12, Spinal nerves. 13,
13, The brachial plexus. 14, 14, The lumbar and sacral plexus.]

  -=-=-=-=-=-=-=-=-=-=-=-=

755-767. _Give the anatomy of the spinal cord, spinal nerves, and the
sympathetic nerve._ 755. What does the spinal column contain? 756.
Give the extent of the spinal cord. How many enlargements has this
cord? What is said of each enlargement? 757. Into how many parts is
the spinal cord divided? Give the function of these columns.

  -=-=-=-=-=-=-=-=-=-=-=-=

758. The SPINAL NERVES, that connect with the spinal cord, are
arranged in thirty-one pairs, each arising by two roots; an anterior,
or _motor_ root, and a posterior, or _sensitive_ root. Each nerve,
when minutely examined, is found to consist of an aggregate of very
delicate filaments, enclosed in a common cellular envelope.

  -=-=-=-=-=-=-=-=-=-=-=-=

758. How many pairs of nerves issue from the spinal cord? Explain fig.
128. Fig. 129.

  -=-=-=-=-=-=-=-=-=-=-=-=

759. The anterior roots arise from a narrow white line upon the
anterior columns of the spinal cord. The posterior roots arise from a
narrow gray band formed by the internal gray substance of the cord.
They are larger, and the filaments of origin more numerous than those
of the anterior roots. A ganglion is found upon each of the posterior
roots in the openings between the bones of the spinal column through
which the nerve passes.

[Illustration: Fig. 130. A section of the spinal cord, surrounded by its
sheath. B, A spinal nerve, formed by the union of the motor root (C) and
the sensitive root (D.) At D, the ganglion upon this root is seen.]

760. After the formation of the ganglion, the two roots unite, and
constitute a spinal nerve, which passes through the opening between
the vertebræ on the sides of the spinal column. The nerves divide and
subdivide, until their minute filaments ramify on the tissues of the
different organs.

  -=-=-=-=-=-=-=-=-=-=-=-=

759. Give the origin of the anterior roots. Of the posterior roots. In
what respect do the posterior roots differ from the anterior? 760.
When do the two roots unite, and where do they pass?

  -=-=-=-=-=-=-=-=-=-=-=-=

761. The _spinal nerves_ are divided into--

 Cervical,     8 pairs,
 Dorsal,      12 "
 Lumbar,       5 "
 Sacral,       6 "

762. The four lower cervical and upper dorsal pass into each other and
then separate to reunite. This is called the _brach´i-al plex´us_.
From this plexus six nerves proceed, which ramify upon the muscles and
skin of the upper extremities.

763. The last dorsal and the five lumbar nerves form a plexus called
the lumbar, similar to that of the cervical. Six nerves pass from this
plexus, which ramify upon the muscles and skin of the lower
extremities.

764. The last lumbar and the four upper sacral unite to form the
sacral plexus. From this plexus five nerves proceed, that are
distributed to the muscles and skin of the hip and lower extremities.

765. The SYMPATHETIC NERVE[19] consists of a series of _Gan´gli-a_, or
knots, extending each side of the spinal column, forming a chain its
whole length. It communicates with both the cranial and spinal nerves.
With the exception of the neck, there is a ganglion for each
intervertebral space. These ganglia are composed of a mixture of
cineritious and medullary matter, and are supposed to be productive of
peculiar nervous power.

  [19] The structure of this nerve is very complicated, and different
       physiologists ascribe to it various functions. The character of
       its diseases are not well understood.

  -=-=-=-=-=-=-=-=-=-=-=-=

761. Give the division of the spinal nerves. 762. What nerves
constitute the brachial plexus? How many nerves pass from this plexus?
763. How many nerves from the lumbar plexus, and where do they ramify?
764. How is the sacral plexus formed? 765. Of what does the
sympathetic nerve consist? How is the sympathetic nerve distributed?
What exception? Of what are the ganglia composed?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 131. A beautiful representation of the sympathetic
ganglia and their connection with other nerves. It is from the grand
engraving of Manec, reduced in size. A, A, A, The semilunar ganglion and
solar plexus, situated below the diaphragm and behind the stomach. This
ganglion is situated in the region (pit of the stomach) where a blow
gives severe suffering. D, D, D, The thoracic ganglia, ten or eleven in
number. E, E, The external and internal branches of the thoracic ganglia.
G, H, The right and left coronary plexus, situated upon the heart. I, N,
Q, The inferior, middle, and superior cervical ganglia. 1, The renal
plexus of nerves that surrounds the kidneys. 2, The lumbar ganglion. 3,
Their internal branches. 4, Their external branches. 5, The aortic plexus
of nerves that lies upon the aorta. The other letters and figures
represent nerves that connect important organs and nerves with the
sympathetic ganglia.]

766. The GANGLIA may be considered as distinct centres, giving off
branches in four directions; namely, the superior, or ascending, to
communicate with the ganglion above; the inferior, or descending, to
communicate with the ganglion below; the external, to communicate with
the spinal nerves; and the internal, to communicate with the
sympathetic filaments. It is generally admitted that the nerves that
pass from the ganglia are larger than those that entered them; as if
they imparted to the nerve some additional power.

767. The branches of distribution accompany the arteries which supply
the different organs, and form communications around them, which are
called plexuses, and take the name of the artery with which they are
associated. Thus we have the mesenteric plexus, hepatic plexus,
splenic plexus, &c. All the internal organs of the head, neck, and
trunk, are supplied with branches from the sympathetic, and some of
them exclusively; for this reason, it is considered a nerve of organic
life.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is the design of fig, 131? 766. How may the ganglia be
considered? 767. What is said of the branches of the sympathetic
nerve?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XXXVIII.

PHYSIOLOGY OF THE NERVOUS SYSTEM.


768. The brain is regarded by physiologists and philosophers as the
organ of the mind. Most writers consider it as an aggregate of parts,
each charged with specific functions, and that these functions are the
highest and most important in the animal economy. To the large brain,
or cerebral lobes, they ascribe the seat of the faculties of
_thinking_, _memory_, and _the will_. In man, this lobe extends so far
backward as to cover the whole of the cerebellum. To the cerebellum,
or little brain, is ascribed the seat of the _animal_, or _lower
propensities_.

769. "The constant relation between mental power and development of
brain, explains why capacities and dispositions are so different. In
infancy, for example, the intellectual powers are feeble and inactive.
This arises partly from the inaptitude of a still imperfect brain; but
in proportion as the latter advances toward its mature state, the
mental faculties also become vigorous and active."

770. We are able, in most instances, at least, to trace a correspondence
between the development of the cerebral lobes and the amount of
intelligence possessed by the person. The weight of the brain in man
to that of the whole body varies in different individuals. The
heaviest brain on record was that of Cuvier, which weighed 4 pounds
and 13½ ounces.

  -=-=-=-=-=-=-=-=-=-=-=-=

768-772. _Give the physiology of the nervous system._ 768. How is the
brain regarded by physiologists and philosophers? What do they ascribe
to the cerebrum? To the cerebellum? 769. What does the relation
between mental powers and development of brain explain? 770. What is
said respecting the correspondence between the development of the
brain and the amount of intelligence possessed by the person? What is
said of the weight of the brain?

  -=-=-=-=-=-=-=-=-=-=-=-=

771. The brain likewise holds an important relation to all the other
organs of the system. To the muscular system it imparts an influence
which induces contraction of the fibres. By this relation they are
brought under the control of the will. To the skin, eye, and ear, it
imparts an influence that gives sensibility, or the power of feeling,
seeing, hearing, &c.

772. Again, the involuntary functions of the different portions of the
system are more or less influenced by the brain. If the action of this
central organ of the nervous system is destroyed, the functions of the
digestive, respiratory, and circulatory apparatuses will be much
disturbed or entirely suppressed.

773. The brain is the seat of _sensation_. It receives the impressions
made on all parts of the body, through the medium of the sensitive
nerves. That the impressions of external objects, made on these
nerves, be communicated to the brain, where sensation is perceived, it
is necessary that they be not diseased or injured.

_Observation._ There is a plain distinction between sensations and
impressions; the latter are the changes produced in the extremities of
the nerve; the former, the changes produced in the brain and
communicated to the mind.

774. What part of the brain receives the impressions or has the most
intimate relation with the intellectual faculties is unknown. Some
portions, however, are of less importance than others. Large portions
of the cortical, or outer part, are frequently removed without
affecting the functions of this organ. Pieces of the medullary, or
central parts, have been removed by injuries without impairing the
intellect or destroying life. This organ, although it takes cognizance
of every sensation, is, of itself, but slightly sensible. It may be
cut, or parts may be removed without pain, and the individual, at the
same times retain his consciousness.

  -=-=-=-=-=-=-=-=-=-=-=-=

771. What is said of the relation of the brain to all of the organs of
the body? 772. Are the involuntary functions of different parts of the
system influenced by the brain? 773. Where is sensation perceived? By
what agency are the impressions of external objects conveyed to the
brain? What is the difference between sensations and impressions? 774.
Is it known what part of the brain has the most intimate relation with
the intellectual faculties?

  -=-=-=-=-=-=-=-=-=-=-=-=

775. The brain is the seat of the _will_. It superintends the physical
as well as the mental movements, and the medium of communication from
this organ to the muscles, or the parts to be moved, is the motor
nerves. If the brain is in a quiescent state, the muscles are at rest;
if, by an act of the will, the brain sends a portion of nervous
influence to a voluntary muscle, it immediately contracts, and those
parts to which the muscle is attached move. There is no perceptible
interval between the act of the will and the motion of the part.

776. Some physiologists assert, that the medulla oblongata is the
point at which excitement to motion commences, and sensation
terminates; and also, that it possesses the power of originating
motion in itself.

_Observation._ The medulla oblongata, unlike the brain, is highly
sensitive; if slightly punctured, convulsions follow; if much injured,
respiration, or breathing, immediately ceases.

777. It is remarkable that the nerves which arise from the right side
of the spinal cord communicate with the left hemisphere of the
cerebrum, and _vice versa_; this results from the crossing of the
fibres in the medulla oblongata. It follows from this, that if the
right side of the brain receives an injury, the parts of the opposite
side of the body lose their sensibility and motion.

_Observations._ 1st. If the cranial nerves which are connected by a
single root are divided, only the sensation of the part to which they
are distributed is lost. Thus, if the optic nerve is divided, the
sense of vision disappears, but the motions of the eye are performed
as readily as before. But, if the spinal nerves are divided, both
sensation and motion of the part to which they lead are destroyed.

  -=-=-=-=-=-=-=-=-=-=-=-=

What portions have been removed without impairing the intellect? What
is remarkable of the brain? 775. What is the influence of the brain
upon the muscles? 776. What do some physiologists assert of the
medulla oblongata? 777. What is remarkable of the nerves? Give the 1st
observation relative to the cranial nerves.

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. When the spinal cord is divided or compressed, as in fractures of
the spinal column, all parts below the fracture are paralyzed, though
the nerves leading to these parts may be uninjured.

3d. Again, one side of the body or one limb may become insensible, and
the power to move it, be perfectly retained; or the reverse of this
may happen--the power of motion will be lost while sensation remains.
In the former instance, the function of the posterior, or sensitive
column of the spinal cord on one side is destroyed; in the latter, the
anterior, or motor column is affected.

4th. In some cases, both sensation and motion of one side of the body
or one limb are destroyed. In such instances, both the anterior and
the posterior columns of one side of the spinal cord are diseased.

778. Vigorous and controllable muscular contraction requires a sound
and well-developed brain. If this organ is defective in these
particulars, the movements will be inefficient, and may be irregular.
The central organ of the nervous system must, likewise, be in an
active condition, to induce regular, steady, and controllable muscular
movements.

_Observations._ 1st. Persons who have suffered from apoplexy and other
severe diseases of the brain, have an involuntary trembling of the
limbs, which results from a weakened state of the nervous system.

  -=-=-=-=-=-=-=-=-=-=-=-=

To the spinal nerves. What is said of the compression of the spinal
cord? Give the 3d observation relative to the spinal nerves. The 4th
observation. 778. Upon what does vigorous controllable muscular
contraction depend? What causes the involuntary trembling of the limbs
in persons who have suffered from apoplexy?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. The tremor of the hand, that lessens the usefulness or incapacitates
the fine artist or skilful mechanic, in the prime of life, from
pursuing their vocations, may be, and is often, induced by the
influence of intoxicating drink, which debilitates and disorganizes the
brain.

3d. The tottering step, trembling hand, and shaking head of the aged
invalid, are the results of diminished nervous energy, so that steady
muscular contraction, so essential to regular movements, cannot be
maintained.

779. No difference can be discovered in the structure of the several
kinds of nerves in any part of their course, and the functions they
are designed to perform can only be known by ascertaining the place of
their origin. The nerves may be functionally divided into five
groups.

780. 1st. _Nerves of special sensation._ These are the first, second,
eighth, and it may be one of the branches of the fifth pair of cranial
nerves. The function of these nerves is particularly described in the
chapters upon the senses of smell, vision, hearing, and taste.

781. 2d. _Nerves of general sensation._ These embrace the fifth pair
of cranial nerves, and the thirty-one pairs of spinal nerves. In those
parts that require sensation for their safety and the performance of
their functions, there is an abundant supply of sensitive nervous
filaments. The nerves of sensation are mostly distributed upon the
skin. Few filaments ramify upon the mucous membranes and muscles.

_Observations._ 1st. The painful sensations experienced in the face,
and in the teeth or jaws, (tic douloureux and toothache,) are induced
by irritation and disease of a portion of the filaments of the fifth
pair of cranial nerves.

  -=-=-=-=-=-=-=-=-=-=-=-=

The tremor of the hand among some mechanics in the prime of life? The
tottering step of the aged invalid? 779. What is said relative to the
structure of the nerves? How may they be divided? 780. Give the nerves
of special sense. 781. Those of general sensation. Where are the
nerves of sensation distributed? What causes tic douloureux?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. The unpleasant sensation sometimes experienced when we hear the
grating of a file or saw, is produced by the connection of the nerve
that passes across the drum of the ear with the fifth cranial nerve.

3d. When pressure is made on the trunk of a nerve, the sensibility of
the part where the nerve ramifies is modified. This is illustrated,
when pressure is made upon the large nerve of the lower extremity
(sciatic) in sitting upon a hard bench. The foot is then said to be
"asleep."

4th. When the trunk of a nerve is diseased or injured, the pain is
experienced in the outer extremity of the nerve. A blow upon the
elbow, which causes a peculiar sensation in the little finger and one
side of the ring finger, affords a familiar illustration. This
sensation is produced by injuring the ulnar nerve, which is
distributed to the little finger.

782. 3d. _Nerves of motion._ These are the third, sixth, and twelfth
pairs of cranial nerves, and the thirty-one pairs of spinal nerves.
These nerves are distributed to the fibres of the five hundred muscles
of the body. The functions of the muscular are different from those of
the sensitive nerves. The former are provided for the purpose of
motion, and not of feeling. Hence, muscles may be cut, and the pain
will be slight, compared with the cutting of the skin. This may be
called muscular pain. Weariness is a sensation recognized by one set
of muscular nerves.

783. So uniformly is a separate instrument provided for every
additional function, that there is strong reason to regard the
muscular nerves, although running in one sheath, as in reality double,
and performing distinct functions. Sir Charles Bell, in his work on
the Nervous System, endeavors to show, that one set of nervous fibres
conveys the mandate from the brain to the muscle, and excites the
contraction; and that another set conveys, from the muscle to the
brain, a peculiar sense of the state or degree of contraction of the
muscle, by which we are enabled to judge of the amount of stimulus
necessary to accomplish the end desired. This is obviously an
indispensable piece of information to the mind in regulating the
movements of the body.

  -=-=-=-=-=-=-=-=-=-=-=-=

How is the peculiar sensation accounted for when we hear the grating
of a file or saw? What produces the sensation when the foot is said to
be "asleep?" What is the effect when the ulnar nerve is injured by a
blow? 782. Give the nerves of motion. What is said of the functions of
the muscular nerves? 783. What does Sir Charles Bell endeavor to
show?

  -=-=-=-=-=-=-=-=-=-=-=-=

784. 4th. _Nerves of respiration._ These are the fourth, seventh,
ninth, tenth, and eleventh pair of cranial nerves, also the phrenic
and the external respiratory nerve. All of these nerves have their
origin in a distinct tract or column, called the lateral, in the upper
part of the spinal cord. Hence it is sometimes named the respiratory
column. These nerves are distributed to one of the muscles of the eye;
to the muscles of the face; to the tongue, pharynx, oesophagus,
stomach, heart, lungs, diaphragm, and some of the muscles of the neck
and chest.

785. It is through the instrumentality of the accessory, phrenic,
and external respiratory nerves, (10, 11, 12, 13, fig. 132,) that
the muscles employed in respiration are brought into action without
the necessity of the interference of the mind. Though to a certain
extent they may be under the influence of the will, yet it is only in
a secondary degree. No one can long suspend the movements of
respiration;[20] for in a short time, instinctive feeling issues
its irresistible mandate, which neither requires the aid of erring
wisdom, nor brooks the capricious interference of the will.

  [20] Dr. Elliotson, and some other writers On physiology, have
       detailed cases of death from voluntary suspension of respiration.
       But these cases are not conclusive, as examinations were not
       made, so as to determine positively, that death did not result
       from disease of the heart, brain, or some other vital organ.

[Illustration: Fig. 132. The distribution of the respiratory nerves. _a_,
Section of the brain and medulla oblongata. _b_, The lateral columns of
the spinal cord. _c_, _c_, The respiratory tract of the spinal cord. _d_,
The tongue. _e_, The larynx. _f_, The bronchia. _g_, The oesophagus. _h_,
The stomach. _i_, The diaphragm. 1, The pneumogastric nerve. 2, The
superior laryngeal nerve. 3, The recurrent laryngeal nerve. (These two
ramify on the larynx.) 4, The pulmonary plexus of the tenth nerve. 5, The
cardiac plexus of the tenth nerve. These two plexuses supply the heart
and lungs with nervous filaments. 7, The origin of the fourth pair of
nerves, that passes to the superior oblique muscle of the eye. 8, The
origin of the facial nerve, that is spread out on the side of the face
and nose. 9, The origin of the glosso-pharyngeal nerve, that passes to
the tongue and pharynx. 10, The origin of the spinal accessory nerve. 11,
This nerve penetrating the sterno-mastoideus muscle. 12, The origin of
the internal respiratory or phrenic nerve, that is seen to ramify on the
diaphragm. 13, The origin of the external respiratory nerve, that
ramifies on the pectoral and scaleni muscles.]

  -=-=-=-=-=-=-=-=-=-=-=-=

784. Give the respiratory nerves. What is said in reference to the
respiratory nerves? 785. Through the agency of what nerves are the
respiratory muscles brought into action? Explain fig. 132.

  -=-=-=-=-=-=-=-=-=-=-=-=

786. The fourth, seventh, and tenth pairs of nerves, (7, 8, 9, fig.
132,) with the spinal accessory, phrenic, and external respiratory,
are not only connected with the function of respiration, but
contribute to the expression of the passions and emotions of the
mind.

787. The influence of this order of nerves in the expression of the
passions, is strikingly depicted in Sir Charles Bell's Treatise on the
Nervous System. "In terror," he remarks, "we can readily conceive why
a man stands with his eyes intently fixed on the object of his
fears--the eyebrows elevated, and the eyeballs largely uncovered; or
why, with hesitating and bewildered steps, his eyes are rapidly and
wildly in search of something. In this way, we only perceive the
intense application of his mind to the objects of his apprehension,
and its direct influence on the outward organs."

  -=-=-=-=-=-=-=-=-=-=-=-=

Can respiration be suspended for any considerable length of time? 786.
What nerves contribute to the expression of the passions and emotions
of the mind? 787, 788. What does Sir Charles Bell say of the influence
of this order of nerves in the expression of the passions?

  -=-=-=-=-=-=-=-=-=-=-=-=

788. "But when we observe him further, there is a spasm in his breast;
he cannot breathe freely; the chest remains elevated, and his
respiration is short and rapid. There is a gasping and convulsive
motion of his lips, a tremor on his hollow cheeks, a gasping and
catching of his throat; his heart knocks at his ribs, while yet there
is no force in the circulation--the lips and cheeks being ashy pale."

789. "These nerves are the instruments of expression, from the smile
upon the infant's cheek, to the last agony of life. It is when the
strong man is subdued by this mysterious influence of soul on body,
and when the passions may be truly said to tear the heart, that we
have the most afflicting picture of human frailty, and the most
unequivocal proof that it is the order of functions we have been
considering, that is thus affected. In the first struggle of the
infant to draw breath, in the man recovering from a state of
suffocation, and in the agony of passion, when the breast labors from
the influence at the heart, the same system of parts is affected, the
same nerves, the same muscles, and the symptoms or character have a
strict resemblance."

790. The seventh pair of nerves not only communicates the purposes of
the will to the muscles of the face, but at the same time it calls
them into action, under the influence of instinct and sympathy. On
this subject a late writer remarks, "How expressive is the face of
man! How clearly it announces the thoughts and sentiments of the mind!
How well depicted are the passions on his countenance! tumultuous
rage, abject fear, devoted love, envy, hatred, grief, and every other
emotion, in all their shades and diversities, are imprinted there, in
characters so clear that he that runs may read! How difficult, nay,
how impossible, is it to hide or falsify the expressions which
indicate the internal feelings! Thus conscious guilt shrinks from
detection, innocence declares its confidence, and hope anticipates
with bright expectation."

_Observation._ The fifth pair of nerves (fig. 126) is distributed to
the parts of the face on which the seventh pair ramifies. The former
serves for sensation, the latter for motion. Thus, when the seventh
pair of nerves is divided, or its functions destroyed by disease, the
side affected loses all power of expression, though sensation remains
unaffected. On the contrary, if we divide the fifth pair, sensation is
entirely destroyed, while expression remains.

  -=-=-=-=-=-=-=-=-=-=-=-=

789. Are they also the instruments of expression, either of joy or
grief? 790. What is said in reference to the seventh pair of nerves?
Where is the fifth pair of nerves distributed?

  -=-=-=-=-=-=-=-=-=-=-=-=

791. 5th. _The sympathetic nerve._ This nerve confers vitality on all
the important portions of the system. It exerts a controlling
influence over the involuntary functions of digestion, absorption,
secretion, circulation, and nutrition. Every portion of the body is,
to a certain extent, under its influence, as filaments from this
system of nerves accompany the blood-vessels throughout their course.

792. An important use of the sympathetic nerve is to form a
communication of one part of the system with another, so that one
organ can take cognizance of the condition of every other, and act
accordingly. If, for example, disease seizes the brain, the stomach,
by its sympathetic connection, knows it; and as nourishment would add
to the disease, it refuses to receive food, and perhaps throws off
what has already been taken. Loss of appetite in sickness is thus a
kind provision of nature, to prevent our taking food when it would be
injurious; and following this intimation, we, as a general rule,
should abstain from food until the appetite returns.

[Illustration: Fig. 133. A back view of the brain and spinal cord. 1, The
cerebrum. 2, The cerebellum. 3, The spinal cord. 4, Nerves of the face.
5, The brachial plexus of nerves. 6, 7, 8, 9, Nerves of the arm. 10,
Nerves that pass under the ribs, 11, The lumbar plexus of nerves. 12, The
sacral plexus of nerves 13, 14, 15, 16, Nerves of the lower limbs.]

  -=-=-=-=-=-=-=-=-=-=-=-=

What is the function of this nerve? What is the effect if the seventh
pair is divided, or its function destroyed by disease? 791. What is
said of the sympathetic nerve? 792. What is the use of the sympathetic
system? Explain fig. 133.

  -=-=-=-=-=-=-=-=-=-=-=-=

_Note._ Let the anatomy and physiology of the nervous system be
reviewed from figs. 131, 132, 133, or from anatomical outline plate.
No. 8.



CHAPTER XXXIX.

HYGIENE OF THE NERVOUS SYSTEM.


793. As the different organs of the system are dependent on the brain
and spinal cord for efficient functional action, and as the mind and
brain are closely associated during life, the former acting in strict
obedience to the laws which regulate the latter, it becomes an object
of primary importance in education, to discover what these laws are,
that we may escape the numerous evils consequent on their violation.

794. _For healthy and efficient action, the brain should be primarily
sound_; as this organ is subject to the same general laws as other
parts of the body. If the brain of the child is free from defects at
birth, and acquires no improper impressions in infancy, it will not
easily become diseased in after life. But, if the brain has inherited
defects, or has acquired a proneness to disease by mismanagement in
early life, it will more easily yield to influences that cause
diseased action. The hereditary tendency to disease is one of the most
powerful causes that produce nervous and mental affections.
Consequently, children have a strong tendency to the diseases from
which the parents suffered.

795. When both parents have similar defects, or have descended from
tainted families, the children are usually more deeply impressed with
their imperfections than when only one possesses the defect. This is
the reason of the frequency of nervous disease and imbecility among
the opulent, as intermarriages among near relations are more frequent
with this class than among the poor.

  -=-=-=-=-=-=-=-=-=-=-=-=

793-850. _Give the hygiene of the nervous system._ 793. Why is it
important to know the laws which regulate the action of the brain?
794. What is necessary that the action of the brain be healthy and
efficient? What follows if the brain of the child has inherited
defects? 795. What is the effect when both parents possess similar
defects?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ Among some of the reigning families of Europe,
particularly the Spanish, the folly of intermarriage among themselves
is strongly illustrated. The high and noble talents that characterized
their progenitors are not seen, but there is now exhibited, among
their descendants, imbecility and the most revolting forms of nervous
disease.

796. "Unhappily, it is not merely as a cause of disease, that
hereditary predisposition is to be dreaded. The obstacles which it
throws in the way of permanent recovery are even more formidable, and
can never be entirely removed. Safety is to be found only in avoiding
the perpetuation of the mischief."

797. "Therefore, if two persons, each naturally of excitable and
delicate nervous temperament, choose to unite for life, they have
themselves to blame for the concentrated influence of similar
tendencies in destroying the health of their offspring, and
subjecting them to all the miseries of nervous disease, madness, or
melancholy." The command of God not to marry within certain degrees
of consanguinity, is in accordance with the organic laws of the
brain, and the wisdom of the prohibition is confirmed by observation.

_Observation._ The inhabitants, females particularly, of the sea-girt
islands of America, are more affected with nervous diseases, than
those who reside upon the mainland. The prevalence of these affections
is ascribed to the frequent intermarriage of persons closely related
by blood.

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What is one cause of nervous disease among the higher classes? What is
true of some of the reigning families of Europe? 796. Why is
hereditary predisposition to be dreaded? 797. Is the prohibition of
God respecting intermarriage in accordance with the organic laws of
the brain? What is said of the inhabitants of the sea-girt islands of
America?

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798. _The brain requires a due supply of pure blood._ This organ
receives an unusually large supply of blood, in comparison with the
rest of the body. It is estimated that one tenth of all the blood sent
from the heart goes to this organ. If the arterial blood be altogether
withdrawn, or a person breathes air that is filled with carbonic gas,
the brain ceases its proper action, and sensibility with consciousness
becomes extinct.

_Illustrations._ 1st. If a person lose a considerable quantity of
blood, dizziness and loss of consciousness follow. This results from
the brain not receiving a sufficient amount of blood to sustain its
functions.

2d. When an individual descends into a well or pit that contains
carbonic acid, the blood is not changed or purified in the lungs, and
loss of consciousness and death soon follow.

799. The slighter variations in the state of the blood have equally
sure, though less palpable effects. If its vitality is impaired by
breathing an atmosphere so much vitiated as to be insufficient to
produce the proper degree of oxygenation, the blood then affords an
imperfect stimulus to the brain. As a necessary consequence, languor
and inactivity of the mental and nervous functions ensue, and a
tendency to headache, fainting, or hysteria, makes its appearance.

_Observations._ 1st. Let a person remain, for a time, in a crowded,
ill-ventilated, hall or church, and headache or faintness is generally
produced. This is caused by the action of impure blood upon the
brain.

2d. If a school-teacher wishes to have his pupils, on the day of
examination, appear creditably, he will be careful to have the room
well ventilated. Ventilating churches might prevent the inattention
and sleepiness that are observed during the afternoon service.

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798. Why does the brain require a due supply of pure blood? What is
the effect when a person loses a considerable quantity of blood? What
causes the loss of consciousness when carbonic acid is breathed? 799.
What effects are produced by slight variations in the quality of the
blood? From the following observations, give some of the effects of
impure blood on the brain.

  -=-=-=-=-=-=-=-=-=-=-=-=

3d. In many instances, the transmission of imperfectly oxygenated
blood to the brain, is an influential cause in the production of
nervous disease and delicacy of constitution. The only efficient
remedy for these conditions is a supply of pure blood to the brain.

800. _The brain should be called into action._ This organ, like the
muscles, should be used, and then allowed to rest, or cease from
vigorous thought. When the brain is properly called into action by
moderate study, it increases in size and strength; while, on the other
hand, if it is not used, the action of this organ is enfeebled,
thereby diminishing the function of all parts of the body.

801. The brain, being an organized part, is subject, so far as regards
exercise, to the same laws as the other organs of the body. If it is
doomed to inactivity, its size diminishes, its health decays, and the
mental operations and feelings, as a necessary consequence, become
dull, feeble, and slow. If it is duly exercised after regular
intervals of repose, the mind acquires readiness and strength. Lastly,
if it is overtasked, either in the force or duration of its activity,
its functions become impaired, and irritability and disease take the
place of health and vigor.

802. The consequences of inadequate exercise will first be explained.
We have seen that by disuse the muscles become emaciated, the bones
soften, and the blood-vessels are obliterated. The brain is no
exception to this general rule. It is impaired by permanent
inactivity, and becomes less fit to manifest the mental powers with
readiness and energy. Nor will this surprise any reflecting person,
who considers that the brain, as a part of the same animal system, is
nourished by the same blood and regulated by the same vital laws as
the muscles, bones, and arteries.

  -=-=-=-=-=-=-=-=-=-=-=-=

800. Why should the brain be called into action? 801. What is the
effect if the brain is doomed to inactivity? 802. Show the consequences
of disuse of the organs mentioned in preceding chapters. Does the
same principle apply to the brain?

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803. It is the weakening and depressing effect which is induced by the
absence of the stimulus necessary for the healthy exercise of the
brain, that renders solitary confinement so severe a punishment, even
to the most daring minds. Keeping the above principle in view, we
shall not be surprised to find that _non-exercise_ of the brain and
nervous system, or, in other words, inactivity of intellect and
feeling, is a very frequent predisposing cause of every form of
nervous disease.

804. For demonstrative evidence of this position, we have only to look
at the numerous victims to be found among females of the middle and
higher ranks, who have no calls to exertion in gaining the means of
subsistence, and no objects of interest on which to exercise their
mental faculties, and who, consequently, sink into a state of mental
sloth and nervousness, which not only deprives them of much enjoyment,
but subjects them to suffering, both of body and mind from the
slightest causes.

805. But let the situation of such persons be changed; bring them, for
instance, from the listlessness of retirement to the business and
bustle of the city; give them a variety of imperative employments, and
so place them in society as to supply to their cerebral organs that
extent of exercise which gives health and vivacity of action, and in a
few months the change produced will be surprising. Health, animation,
and energy, will take the place of former insipidity and dulness.

806. An additional illustration, involving an important principle in
the production of many distressing forms of disease will be found in
the case of a man of mature age, and of active habits, who has devoted
his life to the toils of business, and whose hours of leisure have
been few and short. Suppose such a person to retire to the country in
search of repose, and to have no moral, religious, or philosophical
pursuits to occupy his attention and keep up the active exercise of
his brain; this organ will lose its health, and the inevitable result
will be, weariness of life, despondency, or some other variety of
nervous disease.

  -=-=-=-=-=-=-=-=-=-=-=-=

803. What renders solitary confinement so severe a punishment to the
most daring minds? What is a predisposing cause of nervous disease?
804. In what classes do mental and nervous debility prevail? 805. How
can this be counteracted? 806. Give another illustration, showing how
disease of the brain is induced.

  -=-=-=-=-=-=-=-=-=-=-=-=

807. One great evil attending the absence of some imperative
employment or object of interest, to exercise the mind and brain, is
the tendency which it generates to waste the mental energies on every
trifling occurrence which presents itself, and to seek relief in the
momentary excitement of any sensation, however unworthy. The best
remedy for these evils is to create occupation to interest the mind,
and give that wholesome exercise to the brain, which its constitution
requires.

808. _The evils arising from excessive or ill-timed exercise of the
brain, or any of its parts, are numerous._ When we use the eye too
long, or in too bright a light, it becomes bloodshot. The increased
action of its vessels and nerves gives rise to a sensation of fatigue
and pain, requiring us to desist. If we relieve the eye, the
irritation gradually subsides and the healthy state returns. But, if
we continue to look intently, or resume our employment before the eye
has regained its natural state by repose, the irritation at last
becomes permanent, and disease, followed by weakness of vision, or
even blindness, may ensue.

809. Phenomena precisely analogous occur, when, from intense mental
excitement, the brain is kept long in a state of excessive activity.
The only difference is, that we can always see what happens in the
eye, but rarely what takes place in the brain; occasionally, however,
cases of fracture of the skull occur, in which, part of the bone being
removed, we can see the quickened circulation in the vessels of the
brain, as easily as those of the eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

807. What is one great evil attending the absence of some imperative
employment to exercise the mind and brain? What is the true remedy for
these evils? 808. From what other cause do evils arise to the brain?
Explain the evil of it by the excessive use of the eye. 809. What is
the only difference in the analogy of the phenomena of the eye and
brain? Has the analogy been verified?

  -=-=-=-=-=-=-=-=-=-=-=-=

810. Sir Astley Cooper had a young man brought to him, who had lost a
portion of his skull, just above the eyebrow. "On examining the head,"
says Sir Astley, "I distinctly saw that the pulsation of the brain was
regular and slow; but at this time he was agitated by some opposition
to his wishes, and directly the blood was sent with increased force to
the brain, and the pulsation became frequent and violent."

811. Indeed, in many instances, the increased circulation in the
brain, attendant on mental excitement, reveals itself when least
expected, and leaves traces after death, which are very perceptible.
When tasked beyond its strength, the eye becomes insensible to light,
and no longer conveys any impressions to the mind. In like manner, the
brain, when much exhausted, becomes incapable of thought, and
consciousness is almost lost in a feeling of utter confusion.

812. _At any time of life, excessive and continued mental exertion is
hurtful_; but in infancy and early youth, when the structure of the
brain is still immature and delicate, permanent mischief is more
easily produced by injudicious treatment than at any subsequent
period. In this respect, the analogy is as complete between the brain
and the other parts of the body, as that exemplified in the injurious
effects of premature exercise of the bones and muscles.

813. Scrofulous and rickety children are the most usual sufferers in
this way. They are generally remarkable for large heads, great
precocity of understanding, and small, delicate bodies. But in such
instances, the great size of the brain, and the acuteness of the mind,
are the results of morbid growth. Even with the best of management,
the child passes the first years of its life constantly on the brink
of active disease.

  -=-=-=-=-=-=-=-=-=-=-=-=

810. Relate the case detailed by Sir Astley Cooper. 811. May the
increased functional action of the brain change its structure? 812. At
what age particularly is excessive and continued mental exertion
hurtful? 813. What is said of scrofulous and rickety children?

  -=-=-=-=-=-=-=-=-=-=-=-=

814. Instead, however, of trying to repress its mental activity, the
fond parents, misled by the early promise of genius too often excite
it still further, by unceasing cultivation, and the never-failing
stimulus of praise. Finding its progress for a time equal to their
warmest wishes, they look forward with ecstasy to the day when its
talents will break forth and shed lustre on its name.

815. But in exact proportion as the picture becomes brighter to their
fancy, the probability of its being realized becomes less; for the
brain, worn out by premature exertion, either becomes diseased, or
loses its tone, leaving the mental powers imbecile and depressed for
the remainder of life. The expected prodigy is thus easily outstripped
in the social race by many whose dull outset promised him an easy
victory.

816. Taking for our guide the necessities of the constitution, it will
be obvious that the modes of treatment commonly resorted to ought to
be reversed. Instead of straining to the utmost the already irritable
powers of the precocious child, and leaving his dull competitor to
ripen at leisure, a systematic attempt ought to be made, from early
infancy, to rouse to action the languid faculties of the latter, while
no pains ought to be spared to moderate and give tone to the activity
of the former.

817. Instead of this, however, the prematurely intelligent child is
sent to school and tasked with lessons at an unusually early age,
while the healthy but more backward boy, who requires to be
stimulated, is kept at home in idleness, perhaps for two or three
years longer, merely on account of his backwardness. A double error is
here committed. The consequences to the intelligent boy are,
frequently, the permanent loss both of health and of his envied
superiority of intellect.

  -=-=-=-=-=-=-=-=-=-=-=-=

814. How are such children usually managed? 815. What is the cause of
their early promise and subsequent disappointment? 816. What mode of
treatment should be adopted in educating precocious children? 817. How
should the dull or less active child be treated? What is the usual
course?

  -=-=-=-=-=-=-=-=-=-=-=-=

818. In youth, too, much mischief is done by the long daily period of
attendance at school, and the continued application of the mind which
the ordinary system of education requires. The law of exercise--that
long-sustained action exhausts the vital powers of the organ--applies
as well to the brain as to the muscles. Hence the necessity of varying
the occupations of the young, and allowing frequent intervals of
exercise in the open air, instead of "enforcing the continued
confinement now so common."

_Observation._ It is no unusual occurrence, that on examination day,
the best scholars appear indifferently. This may be the result of
nervous exhaustion, produced by extra mental effort in preparing for
the final examination. It is advisable for such pupils to divert their
minds from close study for a few days previous to examination. During
this time, the student may indulge in physical recreation, social
intercourse, and a moderate amount of reading.

819. "In early and middle life, fever, an unusual degree of cerebral
disorder, is a common consequence of the excessive and continued
excitement of the brain. This unhappy result is brought on by severe
study, unremitted mental exertion, anxiety, and watching. Nervous
disease, from excessive mental labor and high mental excitement,
sometimes shows itself in another form.

  -=-=-=-=-=-=-=-=-=-=-=-=

What are the consequences of the error? 818. What error prevails in
the present system of education? Why should youths be allowed frequent
intervals to exercise in the open air? Give observation. 819. What is
a frequent consequence of continued and excessive excitement of the
brain?

  -=-=-=-=-=-=-=-=-=-=-=-=

820. "From the want of proper intervals of rest, the vascular
excitement of the brain has not time to subside. A restless
irritability of temper and disposition comes on, attended with
sleeplessness and anxiety, for which no external cause can be
assigned. The symptoms gradually become aggravated, the digestive
functions give way, nutrition is impaired, and a sense of wretchedness
is constantly present, which often leads to attempts at suicide."

_Observations._ 1st. Moderation in mental exertion is more necessary
in old age than in early or mature years. In youth and manhood, the
exhaustion of the brain from over-excitement may be repaired, but no
such result follows over-exertion in the decline of life. "What is
lost then, is lost forever." At that period, the brain becomes
excited, and is soon exhausted when forced to protracted and vigorous
thought. Sir Walter Scott and President Harrison afford sad examples
of premature death from overtasked brains at an advanced period of
their lives.

2d. If the mind is incessantly engaged in the contemplation of the
same object, there is danger from over-exertion of the brain at any
period of life, but more particularly in old age. The more limited the
sphere of mental action, the greater the danger of the brain being
over-exercised. Hence the frequency of nervous diseases in poets,
mathematicians, and musicians.

  -=-=-=-=-=-=-=-=-=-=-=-=

820. What often manifests itself from the want of proper intervals of
rest? Why is moderation in mental action necessary in old age? What is
the effect if the mind is incessantly engaged in the contemplation of
the same object?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XL.

HYGIENE OF THE NERVOUS SYSTEM, CONTINUED.


821. Having pointed out the evils arising both from inadequate and
from excessive mental exertion, it remains to direct the attention to
some of the rules which should guide us in the exercise of the brain.

822. _We should not enter upon continued mental exertion, or arouse
deep feeling, immediately before or after a full meal._ Such is the
connection between the mind and body, that even in a perfectly healthy
person, unwelcome news, sudden anxiety, or mental excitement,
occurring soon after eating, will impede digestion, and cause the
stomach to loathe the masticated food.

823. The worst forms of indigestion and nervous depression are those
which arise from excessive mental application, or depressed feeling,
conjoined with unrestrained indulgence in the pleasures of the table.
In such circumstances, the stomach and brain react upon and disturb
each other, till all the horrors of nervous disease make their
unwelcome appearance, and render life miserable. Too many literary men
and students know this from sad experience.

824. _We should engage in intense study in the early part of the day._
Nature has allotted the darkness of the night for repose, and for
restoration by sleep of the exhausted energies of mind and body. In
the early part of the evening, if study or composition be ardently
engaged in, the increased action of the brain, which always
accompanies activity of mind, requires a long time to subside. If the
individual possesses a nervous temperament, he will be sleepless for
hours after he has retired, or perhaps be tormented by unpleasant
dreams.

  -=-=-=-=-=-=-=-=-=-=-=-=

822. Why should we not arouse deep feeling immediately before or after
eating a full meal? 823. How are the worst forms of indigestion and
nervous depression produced? What class of men know this from sad
experience? 824. What evils arise from studious application at night?

  -=-=-=-=-=-=-=-=-=-=-=-=

825. It is, therefore, of great advantage to enter upon intense mental
application early in the day, and to devote several of the hours which
precede bedtime to entertaining conversation, music, and lighter
reading. The vascular excitement previously induced in the brain by
study, has then time to subside, and sound, refreshing sleep is much
more certainly obtained. This rule is of great consequence to those
who are obliged to undergo much mental labor.

_Observation._ The idea of gathering wisdom by burning the "midnight
oil," is more poetical than profitable. The best time to use the brain
is during the day.

826. _The close student and the growing child need more sleep than the
idler or the adult._ As steep is the natural repose of all organs, it
follows that the more the brain and other organs of the system are
employed, the more repose they require. The organs of the child,
beside sustaining their proper functions, are busy in promoting its
growth. This nutritive process is attended with a certain degree of
exhaustion. The impaired health of children often results from a
disregard of this principle. But, on the other hand, an excess of
sleep produces feebleness, by preventing the proper exercise of the
mind as well as the body.

827. _The length of time the brain may be advantageously used, is
modified by many circumstances._ The power of the brain in different
persons to endure action, is various. This is modified by its primary
character; by development and age; by habits of action; by the health
of the cerebral organ and general system; by the moral feelings and
other conditions.

  -=-=-=-=-=-=-=-=-=-=-=-=

825. Why should we engage in intense study in the early part of the
day? 826. What persons require the most sleep? Why? 827. What is said
relative to the length of time that the brain can be advantageously
used? Give a condition that modifies the amount of mental labor.

  -=-=-=-=-=-=-=-=-=-=-=-=

828. The primary physical organization of some individuals is such,
that they are enabled to endure with impunity an amount of mental
labor that would disorder, if not destroy functionally, the cerebral
organ of others differently constituted. Napoleon Bonaparte was of
this number. There can be no fixed period for mental labor, that may
be adopted as a rule for all persons whose systems are maturely
developed. Much less is there a proper definite period for study, that
is applicable to all children.

_Observation._ The practice of retaining pupils of all ages, from five
to twenty years, in the school-room the same period of time, for the
purpose of study, is not predicated upon any law of physiology. An
exercise of three hours, with one or two recesses of ten minutes each,
may profit the eldest class; two hours with a recess of ten minutes,
the middle class; while one hour, or one hour and a half, with one
recess, would be as long a period as the youngest pupils should be
retained in the study-room at one session.

829. A person who is accustomed to muscular exertion will endure a
longer period of physical toil than one who is not inured to it. So it
is with mental labor. If the brain has been habituated to mental
action and profound study, it will not be so soon fatigued as when not
accustomed to such exertions; consequently, an amount of mental labor
may be performed with impunity at one time, that would exhaust and
cause serious disease of the cerebral organ at another.

_Observation._ Persons that commence a course of study at a late
period in life, frequently evince their zeal at the commencement by
poring over their books twelve or more hours each day. The progress of
such students is soon arrested by physical and mental depression. In
such instances, it would be more judicious to commence with only three
or four hours' vigorous application each day, and gradually protract
the period of study five or more minutes every successive day, until
the brain may be called into vigorous action six or eight hours with
impunity.

  -=-=-=-=-=-=-=-=-=-=-=-=

828. Why can there be no fixed period for mental labor? What is said
of the practice of retaining pupils of all ages the same period of
time in the school-room? 829. Show that the action of the brain is
influenced by habit, as well as the muscular system. What suggestion
to those persons that commence a course of study at a late period in
life?

  -=-=-=-=-=-=-=-=-=-=-=-=

830. The amount of mental power is greatly influenced by the general
health. Such is the intimate connection of the different parts of the
system, particularly the digestive apparatus, with the cerebral
organs, that except there be vigor of constitution, and freedom from
disease, mental efforts will be feeble and of little avail.

_Observation._ The prevalent opinion, that individuals who are feeble
or diseased may acquire a collegiate education, and thus become useful
to themselves and the community, is very generally erroneous. Such
persons should enter upon a daily and systematic course of physical
training, and their labor should be in the open air, in order that the
system may be invigorated and freed from disease.

831. The moral feelings exert a controlling influence over the
functions of the muscular, digestive, and respiratory organs. They
also exert an influence, perhaps, more powerful upon the nervous
system. While fear and anxiety depress, hope and the enlivening
emotions, facilitate the functional activity of the brain, and
increase its power for mental exertion. By a proper and systematic
education of the moral feelings, they are not only a source of
happiness, and productive of right conduct, but aid in the culture of
the intellect. Consequently, we should cultivate a feeling of hopeful
trust in the future, and a firm reliance upon the laws which the
Creator has given us for our guidance.

  -=-=-=-=-=-=-=-=-=-=-=-=

830. Show that the amount of mental power is modified by the general
health. What is said of feeble persons acquiring a collegiate
education? 831. Do the moral feelings exert a controlling influence
over the principal functions of the system? What is the effect of a
proper and systematic culture of the moral feelings?

  -=-=-=-=-=-=-=-=-=-=-=-=

832. _Regularity is very important in exercising the moral and
intellectual powers._ Periodicity, or a tendency to resume the same
mode of action at stated times, is peculiarly the characteristic of
the nervous system. If we repeat any kind of mental effort every day
at the same hour, we at last find ourselves entering upon it without
premeditation when the time approaches. In like manner, if we arrange
our studies in accordance with this law, and take up each in the same
order, a natural aptitude is soon produced, which renders application
more easy than by resuming the subjects as accident may direct.

_Observation._ When engaged in abstruse studies, it may be found
advantageous to pursue others that are less difficult. The intense
application of the brain, which is requisite in the one instance, is
relieved by directing the attention to a study that requires less
thought. By this change, there is mental relaxation attended with
invigoration of the cerebral organ. Or, it may be explained by
assuming, that the brain is composed of an aggregate of distinct
organs, each of which is called into action in pursuing different
studies.

833. Effective study is impossible if the powers of the brain are
depressed. When the cerebral organ has been temporarily debilitated by
protracted intellectual efforts, it is ineffectual to attempt any
concentrated mental exercise. This condition of the nervous system is
indicated by confusion of thought and inability to attain results that
usually follow similar efforts. Mental rest in these cases is
required.

_Observation._ Students frequently fail in solving mathematical
problems when the mind is prostrated by continued and excessive effort
to obtain a solution. Not unfrequently after a night's rest the
problem is quickly solved, and the pupil thinks he "dreamed it out."
The true explanation is rest invigorated the exhausted brain, which
fitted it for vigorous and successful thought.

  -=-=-=-=-=-=-=-=-=-=-=-=

832. Why is regularity of great importance in exercising the moral and
intellectual powers? What suggestion when pursuing abstruse studies?
How explained? 833. When is effective study impossible? How is this
condition of the nervous system indicated?

  -=-=-=-=-=-=-=-=-=-=-=-=

834. _The intellect should not be cultivated to the neglect of the
moral and physical powers._ All the faculties require for their
development regular exercise, alternated with intervals of rest. This
is as necessary to the due development of the moral feelings of a
child as in physical training and mental culture. Consequently, those
schools are to be preferred in the education of youth, where the
physical, intellectual, and moral faculties receive each day a due
share of attention and culture.

835. The continuance of healthy and vigorous action in the matured
physical, mental, and moral powers, requires frequent and regular
action, alternated with rest, as much as in their development.
Consequently, those who cultivate one or two of these faculties, to
the neglect of the others, exhibit a marked deficiency of acuteness
and vigor in those not exercised. This defect reacts on the powers
that are vigorous, diminishing the energy and deteriorating all the
other faculties of man.

_Observations._ 1st. If the principles before mentioned are true, the
adult, as well as the child, should spend a part of each day in some
proper physical employment; another portion should be appropriated to
intellectual pursuits; while another should be sedulously devoted to
the cultivation of the moral feelings.

2d. Disease of the corporeal system more frequently occurs when only
one set of faculties is used than when all are equally employed. This
is particularly true of nervous and mental disease, which follows and
is caused by either high intellectual action, or intense moral
emotions, without a due amount of physical exercise.

  -=-=-=-=-=-=-=-=-=-=-=-=

How is the "dreaming out" of problems explained? 834. What is said of
the culture of the intellect? What schools are preferable in the
education of youth? Why? 835. What is the effect of cultivating only
one faculty of the mind? Give observation 1st. Observation 2d.

  -=-=-=-=-=-=-=-=-=-=-=-=

836. _The brain can exercise its full force upon only one object at a
time._ If its energies are directed to two or more operations, neither
will receive that full power of exertion that it would if only one
object had engaged the mind. Although the brain will direct several
operations at the same time when only slight mental effort is
required, yet when one operation becomes difficult, or demands special
attention of the mind, the other will be suspended. This is
illustrated in social conversation while walking. Let it become
necessary to concentrate the nervous power upon the motor organs, and
the conversation declines or ceases.

837. In acquiring an education, or in pursuing any profession or
trade, none of those influences that promote the proper functions of
the body, and tend to increase physical ease, should be neglected.
For, if the brain is occupied with disagreeable sensations, it cannot
concentrate its power as effectively in the various employments of
man.

_Observations._ 1st. The situation, ventilation, light, and warmth of
a school-room, together with the arrangement of the benches, do much
to influence the concentration or distraction of the operations of the
mind. Let there be attached to the school-house a spacious yard
planted with trees; let its architecture be attractive; let the
windows be arranged with regularity, and not with the elevation of a
convict's cell, and the benches, in every respect, be adapted to the
different scholars, so that the position of each may be comfortable,
and we mistake if there is not a greater improvement, in a given
time, in such a school, than where there is an apparent disregard to
the pleasure or comfort of the scholars.

  -=-=-=-=-=-=-=-=-=-=-=-=

836. What is the effect if the brain concentrates its energies on more
than one object at a time? How illustrated? 837. What should be
regarded in pursuing any employment? Why? What is said in reference to
the arrangement of school-rooms?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. Mechanics' shops should receive as much attention, relative to
their situation, light, warmth, &c., as school-rooms. If these are
duly observed, the nervous influence transmitted from the brain to the
muscles will be more stimulating, as well as more abundant;
consequently, labor will be performed with less exhaustion.

838. _Repetition is necessary to make a durable impression on the
mind._ "The necessity of judicious repetition in mental and moral
education, is, in fact, too little adverted to, because the principle
which renders it efficacious has not been understood. To induce
facility of action in the organs of the mind, practice is as essential
as it is in the organs of motion.

839. "In physical education we are aware of the advantages of
repetition. We know that if practice in dancing, fencing, skating, and
riding, is persevered in for a length of time sufficient to give the
muscles the requisite promptitude and harmony of action, the power
will be ever afterward retained, although little called into use;
whereas, if the muscles have not been duly trained, we may reiterate
practice at different intervals, without proportionate advancement.
The same principle applies equally to the moral and intellectual
powers, because these operate by means of material organs.

840. "According to this principle, it follows, that in learning a
language or science, six successive months of application will be more
effectual in fixing it in the mind and making it a part of its
furniture, than double or treble the time, if the lessons are
interrupted by long intervals. Hence it is a great error to begin and
study, and then break off, to finish at a later period. The fatigue
is thus doubled, and the success greatly diminished.

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Of mechanics' shops? 838. Is repetition necessary to make a durable
impression on the mind? Why? 839. How is it with physical education?
840. What follows, according to this principle?

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841. "The best way is to begin at the proper age, and to persevere
till the end is attained. This accustoms the mind to sound exertion,
and not to _fits_ of attention. Hence the evil arising from long
vacations; and also the evil of beginning studies before the age at
which they can be understood, as in teaching children the abstract
rules of grammar, to succeed in which, implies in them a power of
thinking, and an amount of general knowledge, which they do not
possess."

842. _The skull is susceptible of fractures from slight blows._ This
occurs most frequently when the blow is given on the side of the head
above and anterior to the ear. Here the bone is very thin, and often
quite brittle. For these reasons, no instructor, or any person, should
punish a child by striking upon any portion of the head.

_Observation._ A few years since, a teacher in one of the Middle
States gave a pupil a slight blow upon the head. It fractured the
skull and ruptured a blood-vessel of the brain, causing a loss of
consciousness, and finally death.

843. _Concussion of the brain may be produced by blows, or by
violently shaking a person._ As the brain is of pulpy consistence, the
atoms of which it is composed, and the circulation of blood in its
minute vessels, may be disturbed by the vibration from a blow on the
exterior of the skull-bones. This disturbance of the cerebral organ is
attended with unpleasant sensations, dizziness, loss of memory and
consciousness. These may be followed by headache and inflammation of
the brain. Concussion of the brain, and the results above mentioned,
may be produced by the sudden motion attendant on the violent shaking
of a scholar. Consequently, a child should never be seized by the arm
and shaken violently as a method of chastisement.

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841. What is the best way of learning the sciences? 842. Why should
not a child be struck upon any portion of the head? What observation
in this connection? 843. How may concussion of the brain be produced?
What is the effect of each upon the brain of the child?

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_Observation._ Most persons have experienced a disagreeable sensation
and dizziness, caused by falling from a slight elevation, or by
jumping from a carriage. This is the result of a moderate concussion
of the brain.

844. In injuries of the brain, from blows and falls, the symptoms
are usually alarming, and all should possess some information for
such contingencies. In general, such accidents are attended by
insensibility; the skin and extremities are pale and cold, the
pulse is very weak and feeble, and the circulation is less vigorous;
the respiration, also, is less frequent and full.

845. When these symptoms exist, the individual, in the first instance,
should be placed in pure air, and friction and dry warmth should be
applied to the pallid and cold skin. This should be assiduously
persevered in until heat and color are restored to the skin and limbs,
and due action of the heart and arteries has been established. Mild
stimulants may also be used internally, with much advantage. The
sympathizing friends should not be permitted to stand about the
patient, as they vitiate the air. There should be no bleeding until
the skin and extremities become warm. Send for a surgeon without
delay.

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Give an instance where moderate concussion of the brain is produced.
844. What are the symptoms when the brain is injured from blows and
falls? 845. What treatment should be adopted?

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CHAPTER XLI.

THE SENSE OF TOUCH.


846. SENSATION is the perception of external objects by means of the
senses. There are five senses, namely, _Touch_, _Taste_, _Smell_,
_Hearing_, and _Vision_.

847. TOUCH is the sense by which the mind becomes acquainted with some
of the properties of bodies, and enables us determine whether their
surfaces are smooth or rough, their relative temperature, and, to a
certain degree, their form and weight.

848. Some physiologists make a distinction between the sense of touch
and tact. Tact, or feeling, is more general, extending over the whole
surface of the skin and mucous membranes, while touch exists chiefly
in the fingers of man and in the noses of certain quadrupeds.

849. "In the exercise of these functions, tact is considered passive;
as, when any part of the system comes into contact with another body,
a sensation of its presence is given, without the exercise of
volition. On the contrary, touch is active, and is exercised
voluntarily, for the purpose of conveying to the mind a knowledge of
the qualities or properties of the surfaces of bodies; as when we feel
of a piece of cloth to ascertain its qualities, or a polished surface,
to prove its smoothness."

850. In man, the hand is admirably adapted to the exercise of touch.
"The fineness of the skin, its great sensibility, the species of
cushion formed by the sub-cutaneous fat at the extremities of the
fingers, the length and flexibility of these organs, and the
capability of opposing the thumb to the fingers, like a pair of
forceps, are so many conditions essentially favorable to the delicacy
of this sense, and enable us to appreciate with exactitude the
qualities of the bodies we may feel."

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846. Define sensation. How many senses have we? 847-851. _What is said
of the sense of touch?_ 847. Define touch. 848. What is the difference
between touch and tact? 849. In the exercise of these functions, which
is active, and which passive? 850. Why is the hand so admirably
adapted to the exercise of the sense of touch?

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851. The nerves that supply the sense of touch, proceed from the
anterior half of the spinal cord. Where this sense is most acute and
delicate, we find the greatest number of sensitive nervous filaments,
and those of the largest size.

_Observation._ In amputating limbs, and other surgical operations, the
division of the skin causes more pain than all the subsequent steps of
the operation, however protracted. The muscles, cellular membrane, and
fat have but little sensibility; while the bones, tendons, and
ligaments are insensible when not diseased, and may be cut without
causing pain.


HYGIENE OF THE SENSE OF TOUCH.

852. The sense of touch varies in different persons, and also in
individuals of different ages. Thus the sensibilities of the child are
more acute than those of the aged. Although there is an original
difference of sensibility from organization, still, the function of
the nerves of sensation is modified by certain influences.

853. _The healthy or unhealthy, active or inactive state of the brain,
influences the action of the sensitive nerves._ In sound and perfect
sleep, the brain is inactive. In this state, ordinary impressions made
upon the skin are not observed by the sleeping person. Thus the arm
may be blistered while sleeping, when exposed to the warm rays of the
sun, and the individual will not be aware of it at the time.

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851. From what do the nerves proceed that supply this sense? 852-864.
_Give the hygiene of the sense of touch._ 852. Does this sense vary in
different persons? 853. Mention a condition of the brain that
influences the nerves of sensation.

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854. If there is compression of the brain, as when the skull-bones are
depressed, or disease of this organ exists, as in severe typhus fever,
impressions made upon the nerves of the skin will not be noticed. The
same is true when the mind is engaged in intense thought or study;
heat or cold may be so intense as to disorganize the skin, and not to
be noticed.

855. The varying health or condition of the brain usually depresses or
increases the sensitiveness of the skin. This is seen in grief and
fear, which diminish, while hope and joy increase the impressibility
of this tissue. It is not uncommon to see the unfortunate insane
endure exposure to heat and cold with seeming impunity; whereas it
would induce almost insupportable suffering to the sane man. Diseases
of the heart, stomach, and lungs, alter the condition of the brain,
and modify, to a greater or less degree, the sensitiveness of the
skin.

856. _The state of the conducting nervous trunks influences the nerves
of sensation._ If a nervous trunk is compressed or divided, the parts
supplied by nervous filaments from this branch, will be insensible to
the impressions made upon them, and consequently such impressions are
not transmitted to the brain.

_Observation._ When the inside of the arm or lower extremities rests
upon a hard surface, the nerves may be compressed so as to deprive the
parts of sensibility. This condition is called "numbness."

857. _The quantity of blood supplied to the skin modifies its
sensitiveness._ If the quantity of blood is diminished, the
sensibility of the skin will be impaired. This is demonstrated by
noting the effects of cold upon the cutaneous tissue, the application
of which contracts the blood-vessels, and drives the circulating fluid
from this membrane, which is shown by the paleness, as well as by the
shrivelled appearance of the skin. And, if this tissue is wounded
while under the influence of cold, but little pain will be felt, and
this chilling influence may be carried so far as not only to deprive
the part of sensation, but of vitality.

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854. Mention other conditions that affect these nerves. 855. What is
the effect of the varying health or condition of the brain upon the
sensitiveness of the skin? Give instances of this effect. 856. What is
the result if a nervous trunk is divided or compressed? How may
"numbness" in the limbs be produced? 857. Does the quantity of blood
supplied to the skin affect its sensibility?

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858. The influence of the blood upon the sensibility of the skin, is
further demonstrated by the pain experienced when chilled extremities
are suddenly exposed to heat. The nerves, by the sudden dilatation of
the contracted blood-vessels, are put in vivid and rapid motion, which
causes the painful and tingling sensation that we experience. In every
part of the system, sudden changes produce unpleasant sensations, and
frequently a diseased condition of the organs.

_Observation._ When the hands, or other portions of the body, are
frozen, or severely chilled, safety and comfort demand that
circulation be restored to the parts by moderate exercise in a cool
room. Not unfrequently, the vitality of the limb is destroyed by
immersing it in hot water or holding it near the fire.

859. _The quality of the blood also influences sensation._ If the
brain and other parts of the nervous system receive impure blood,
their energy is depressed, and the sensibility of the skin rendered
more or less obtuse.

860. _The condition of the cuticle modifies the impression made upon
the cutaneous nerves._ 1st. When the cuticle has become thick and
hard, like horn, as on the inside of the mason's hand, it enables him
to ply his tools without much suffering, because the thickened cuticle
diminishes the impressions made upon the nerves.

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How is it demonstrated? 858. How is the influence of the blood upon
the skin further demonstrated? How should circulation be restored to
limbs frozen or severely chilled? What should be avoided? 859. Show
how the quality of the blood influences sensation. 860. Give the 1st
condition of the cuticle that influences the impressions made on the
cutaneous nerves.

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861. 2d. When the cuticle is very thin and delicate, as on the hand of
the lady who is unaccustomed to manual labor. Let her pursue some
manual employment for several hours, and the extreme tenuity, or
thinness of the cuticle, will not protect the nerves and parts below
from becoming irritated and inflamed.

862. 3d. When the cuticle is removed by blistering or abrasion, the
pain indicates that the naked nerves are too powerfully stimulated by
the contact of external bodies. 4th. When the cuticle is coated with
impurities, blended with the secretion from the oil-glands, the
sensibility of the skin is lessened.

863. _The sensibility of the cutaneous nerves is modified by being
habituated to impressions._ If, for example, an individual should
immerse his feet in moderately warm water, at first it might induce a
smarting sensation; in a short time, the nerves would not only become
habituated to the warm water, but its warmth night be considerably
increased. The same results follow, if an individual is exposed to a
cold element. The impressions at first are highly disagreeable; but as
soon as the nerves become accustomed to the surrounding atmosphere, it
may impart the most agreeable sensations.

_Illustration._ 1st. Let a person from the tropical regions go to a
colder climate, and the cool mornings of the latter will at first
affect him unpleasantly; but, after a few days' exposure to the cooler
air, the sensation will be far from disagreeable.

2d. Let a person enter a room moderately heated; gradually increase
the temperature, until it attains extreme summer heat; not only the
cutaneous nerves, but the whole system, become habituated to the high
temperature. From these facts we learn that the sensations, are not
always a correct index of the real temperature. A well-adjusted
thermometer will indicate it with unerring certainty.

  -=-=-=-=-=-=-=-=-=-=-=-=

861. The 2d condition. 862. The 3d and 4th condition. 863. Show how
habit influences the sensibility of the cutaneous nerves. Give
illustration 1st. Illustration 2d.

  -=-=-=-=-=-=-=-=-=-=-=-=

864. _Touch is modified, in a high degree, by education._ Thus the
blind, whose "windows of the soul" are closed to the beauties of the
external world, cultivate this sense to such a degree that they can
distinguish objects with great accuracy. And the rapidity with which
they read books prepared for their use, is a convincing proof of the
niceness and extent to which the cultivation of this sense can be
carried.

_Illustrations._ 1st. The cloth-dresser, by the aid of this sense,
distinguishes the quality, as well as the slightest difference of
texture, in the different pieces of cloth.

2d. The miller, from a similar education, quickly detects the quality
of flour or meal, by permitting it to pass between his fingers. The
difference in the texture of cloths, or the quality of the flour,
would not be distinguished by an individual whose tactile sense had
not been trained to make nice comparisons.

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864. Is this sense susceptible of improvement? What persons cultivate
it to a high degree? Give illustration 1st. Illustration 2d.

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CHAPTER XLII.

SENSE OF TASTE.


865. The chief organ of TASTE is the upper surface of the tongue;
though the lips, the palate, the internal surface of the cheeks, and
the upper part of the oesophagus, participate in this function.


ANATOMY OF THE ORGANS OF TASTE.

866. The tongue is a double organ, composed chiefly of muscular
fibres, which run in almost every direction. The two sides are so
perfectly distinct, that sometimes, in paralysis, one side is
affected, while the function of the other remains perfect. It
possesses great versatility of motion, and can be moulded into a great
variety of shapes. In articulation, mastication, and deglutition, the
tongue is an auxiliary to other organs.

867. This organ is abundantly supplied with blood-vessels, having a
large artery sent to each side of it. It is also very largely
furnished with nerves; it receives nervous filaments from the fifth,
ninth, and twelfth pairs of nerves. The branch of the fifth, called
the gustatory, is the nerve of taste and sensibility;[21] the
twelfth, called the hypo-glossal, of voluntary motion. By means of the
ninth, called the glosso-pharyngeal the tongue is brought into
association with the fauces, oesophagus, and larynx. It is of obvious
importance that these parts should act in concert; and this is
effected by the distribution of this nerve.

  [21] Some physiologists impute the sense of taste to the ninth pair of
       nerves; others, to the twelfth pair; while others, again,
       contend that taste is the result of a concurrent action of the
       fifth, ninth, and twelfth pairs of nerves.

  -=-=-=-=-=-=-=-=-=-=-=-=

865. What is the chief organ of taste? What other parts participate in
the function? 866-870. _Give the anatomy of the organs of taste._ 866.
Give the structure of the tongue. 867. Is this organ abundantly
supplied with blood? From what source does the tongue derive its
nerves?

  -=-=-=-=-=-=-=-=-=-=-=-=

[Illustration: Fig. 134. A view of one side of the neck, showing the
nerves of the tongue. 1, A fragment of the temporal bone. 2, 3, 4, 6, 7,
8, 9, 10, 11, 12, Muscles of the tongue, fauces, and neck. 5, The tongue.
13, The common carotid artery. 14, The jugular vein. 15, The external
carotid. 16, The internal carotid. 17, The gustatory branch of the fifth
pair of nerves. 20, The glosso-pharyngeal nerve. 21, The hypo-glossal, or
the muscular nerve of the tongue. 24, The pneumogastric nerve. 25, The
facial nerve.]

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868. What is the appearance of the surface of the tongue? Explain fig.
134.

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868. The surface of the tongue is thickly studded with fine papillæ,
or _vil´li_, which give the organ a velvety appearance. These papillæ
are of three varieties. The first is situated near the base of the
tongue. They belong to the class of mucous follicles. They are larger
than the others, and are called _len-tic´u-lar_, from being shaped
like a lens. These, together with the tonsils, (sometimes called the
almonds of the ears,) secrete mucus, to lubricate the food in the act
of deglutition.

869. The instruments of taste are the two other sets of papillæ. One
set consists of small, oval-shaped bodies, which are scattered over
the whole surface of the tongue. They give it a rough appearance, and
are called the _fil´i-form_ papillæ.

870. The other set of papillæ is called the _fun´gi-form_. They are
larger than the former, and consist of small, rounded heads, supported
on short stalks, something in the shape of mushrooms, from which they
derive their name. In the last two described sets of sensitive
papillæ, the gustatory branch of the fifth pair of nerves ramifies.

_Observation._ By applying strong acids, as vinegar, to the tongue,
with a hair pencil, these points will become curiously lengthened.


PHYSIOLOGY OF THE ORGANS OF TASTE.

871. TASTE is the sense which makes us acquainted with the savor of
substances. When fluids are taken into the mouth, the papillæ dilate
and erect themselves, and the particular impression excited is
transmitted to the brain through filaments of the gustatory nerve.
This sense is closely connected with that of smell. The pleasures
derived from it are strictly sensual and corporeal, and contribute in
no way to the expansion of the mind, like those of hearing and
seeing.

  -=-=-=-=-=-=-=-=-=-=-=-=

How many varieties of papillæ? Describe the first variety. What is the
function of the lenticular papillæ? 869. Describe the filiform
papillæ. 870. The fungiform papillæ? What nerve ramifies in the
fungiform papillæ? How can these papillæ, or points, be seen? 871-875.
_Give the physiology of the organs of taste._ 871. Define taste.

  -=-=-=-=-=-=-=-=-=-=-=-=

872. If dry, solid food is taken, the tongue carries it to the back
side of the mouth, where it receives secretions from the salivary
glands; the saliva, becoming impregnated with its flavor, flows over
the sides of the tongue, and gives to the papillæ a perception of the
savory juice; this impression is then communicated to the brain.

_Observation._ It is supposed that the salts which enter into the
composition of the saliva, are very efficient agents in reducing
substances to a proper state for making impressions on the nerves of
taste. The fact that metals impart a peculiar taste, is owing to a
galvanic shock, and not properly to what we understand by taste.

873. The primary use of taste is to guide animals in the selection of
food, and to warn them against the introduction of noxious articles
into the stomach. In all the inferior animals, we see that the
original design of taste is still answered. But in man, this sense has
been so abused and perverted, by the introduction of stimulants and
condiments, and the endless admixture of different articles of food,
that the simple action of this part seems to have been superseded
almost entirely by acquired taste.

874. In children, this sense is usually acute, and their preference is
for food of the mildest character. And it is also true, that every
person has some peculiarities of taste, or dislikes to particular
articles of food. This may be either constitutional or from the
influence of association.

  -=-=-=-=-=-=-=-=-=-=-=-=

With what sense is this closely connected? What is said of this sense?
872. Give the process by which we taste substances. How can we account
for the taste of metals when applied to the tongue? 873. What is the
primary use of taste? Where do we see it perverted? 874. How is this
sense in children? What is true of every person in reference to
taste?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ This sense has been made to vary more than any other by
the refinements of social life. Thus, the Indian's like or dislike to
particular kinds of food, generally extends to every person of the
same tribe; but among civilized men, no two individuals can be found
alike in all their tastes.

875. This sense is modified by habit, and not unfrequently those
articles, which at first were disgusting, become highly agreeable by
persevering in the use of them. By cultivation, this sense may be made
very acute. Those persons whose business leads them to judge of the
quality of an article by their taste, can discriminate shades of
flavor not perceivable by ordinary persons. Epicures, and tasters of
wines and teas, afford examples.

_Observation._ Many persons impair their taste by bad habits, as
chewing and smoking tobacco, and using stimulating drinks, and pungent
condiments with the food. These indulgences lessen the sensibility of
the nerve, and destroy the natural relish for food.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is true of the Indian? 875. Is this sense modified by habit? Give
instances. How is this sense sometimes impaired?

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CHAPTER XLIII.

SENSE OF SMELL.


876. This sense is located in the air-passages of the _Nose_. To
understand the function of smell, the structure of the nose and nasal
cavities, with the distribution of the olfactory nerves, must be first
examined.


ANATOMY OF THE ORGANS OF SMELL.

877. The NOSE is composed of the _Bones_, _Fi´bro-car´tilages_, and
_Mu´cous Mem´brane_, together with its integuments.

878. The BONES of the nose are the nasal, and the nasal processes of
the upper jaw.

879. The FIBRO-CARTILAGES give form and stability to the framework of
the nose, providing at the same time, by their elasticity, against
injuries. They are five in number.

880. The MUCOUS MEMBRANE, which lines the interior of the nose, is
continuous with the skin externally, and with the lining membrane of
the parts of the throat. The entrance of the nostrils is provided with
numerous hairs, which serve as guardians to the delicate membrane of
the nose.

881. The NASAL FOSSÆ, or nostrils, are two irregular, compressed
cavities, extending from the nose to the pharynx. These cavities are
bounded superiorly by the sphenoid and ethmoid bones; inferiorly, by
the hard palate. In the middle line they are separated from each other
by a bony and fibro-cartilaginous septum; upon the outer wall of each
fossa, in the dried skull, are three projecting processes, termed
spongy bones. In the fresh fossa, these are covered by a mucous
membrane.

  -=-=-=-=-=-=-=-=-=-=-=-=

876. Where is the sense of smell located? 877-884. _Give the anatomy
of the organs of smell._ 877. Name the parts that enter into the
structure of the nose? 878. What bones form the framework of the nose?
879. What is the use of the cartilages? 880. What relation has the
mucous membrane with other membranes of the nose? 881. Describe the
nasal cavities.

  -=-=-=-=-=-=-=-=-=-=-=-=

882. The space that intervenes between the superior and middle spongy
bone, is called the _superior me-a´tus_, or channel; the space between
the middle and inferior bone, is the _middle meatus_; and that between
the inferior bone and the floor of the fossa, is the _inferior
meatus_.

[Illustration: Fig. 135. A vertical section of the middle part of the
nasal cavities. 7, The middle spongy bones. 8, The superior part of the
nasal cavities. 10, The inferior spongy bones. 11, The vomer. 12, The
upper jaw. 13. The middle channel of the nose. 14, The lower channel of
the nose. 17, The palatine process of the upper jaw-bone. 18, The roof of
the mouth covered by mucous membrane. 19, A section of this membrane.]

883. The MEATUSES are passages that extend backward, from the
nostrils, into which are several openings. They are lined by a mucous
membrane, called the _pi-tu´i-ta-ry_, or _schneiderian_, from
Schneider, who first showed that the secretion of the nasal fossæ
proceeded from the mucous membrane, and not from the brain.

  -=-=-=-=-=-=-=-=-=-=-=-=

882. What terms are applied to the spaces between these processes?
What does fig. 135 represent? 883. Define the meatuses. By what are
they lined?

  -=-=-=-=-=-=-=-=-=-=-=-=

884. Upon the mucous membrane of the nasal passages, the olfactory
nerve ramifies, and also a branch of the fifth pair of nerves. This
membrane is of considerable extent in man; and in those animals whose
sense of smell is very acute, it is still more extensive.

[Illustration: Fig. 136. A side view of the passage of the nostrils, and
the distribution of the olfactory nerve. 4, The olfactory nerve. 5, The
fine and curious divisions of this nerve on the membrane of the nose. 6,
A branch of the fifth pair of nerves.]


PHYSIOLOGY OF THE ORGANS OF SMELL.

885. The sense of smell enables us to discern the odor or scent of any
thing. When substances are presented to the nose, the air that is
passing through the nostrils brings the odoriferous particles of
matter in contact with the filaments of the olfactory nerves, that are
spread upon the membrane that lines the air-passages, and the
impression is then transmitted to the brain.

  -=-=-=-=-=-=-=-=-=-=-=-=

884. What nerves ramify upon this membrane? What is represented by
fig. 136? 885-899. _Give the physiology of the organs of smell._ 885.
How does the mind become sensible of odoriferous particles?

  -=-=-=-=-=-=-=-=-=-=-=-=

886. This sense, with that of taste, aids man as well as the inferior
animals, in selecting proper food, and it also gives us pleasure by
the inhalation of agreeable odors. The sense of smell, like that of
taste and touch, may be improved by cultivation. It likewise varies in
different persons.

_Observation._ Sometimes this sense seems to possess a morbid degree
of acuteness in respect to odors, which is highly inconvenient and
even dangerous. With some individuals, the smell of certain fruits,
flowers, cheese, &c., produce nausea and even convulsions.

887. In the inferior animals generally, the sense of smell is more
acute than in man. Thus the bloodhound will track the hare over
the ground for miles, guided only by the odor that it leaves in
its flight. He also traces the progress of his master through
thickly-crowded streets, distinguishing his footsteps from those of
a thousand others, and amidst the odorous particles emanating from a
thousand sources.

_Observation._ In some of the higher orders of the inferior animals,
there is an astonishing acuteness of smell in regard to effluvia that
come from living animals. To these animals, it possesses an importance
in them far beyond what it has in man, by making them acquainted with
the presence of their enemies or their prey, when the eye and ear are
incapable of acting. It is related by travellers in Africa, that they
were always apprised of lions in their vicinity during the night, by
the moans and tremblings of their horses.

888. Smell is somewhat under the control of the will. That is, we
have the power of receiving or rejecting odors that are presented;
thus, if odors are agreeable, we inspire forcibly, to enjoy them; but,
if they are offensive, our inspirations are more cautious, or we close
our nostrils. This sense is likewise modified by habit; odors which,
in the first instance, were very offensive, may not only become
endurable, but even agreeable.

  -=-=-=-=-=-=-=-=-=-=-=-=

886. What is the use of the sense of smell? Can this sense be
improved by cultivation? What is said respecting this sense in some
individuals? 887. What is said of this sense in the bloodhound?
Mention an instance of astonishing acuteness of smell in some of
the higher orders of animals. 888. Show that smell is somewhat under
the control of the will.

  -=-=-=-=-=-=-=-=-=-=-=-=

889. Acuteness of smell requires that the brain and nerve of smell be
healthy, and that the membrane that lines the nose be thin and moist.
Any influence that diminishes the sensibility of the nerves, thickens
the membrane, or renders it dry, impairs this sense.

_Observations._ 1st. _Snuff_, when introduced into the nose, not only
diminishes the sensibility of the nervous filaments, but thickens the
lining membrane. This thickening of the membrane obstructs the passage
of air through the nostrils, and thus obliges "snuff-takers" to open
their mouths when they breathe.

2d. The mucous membrane of the nasal passages is the seat of chronic
catarrh. This affection is difficult of removal, as remedial agents
cannot easily be introduced into the windings of these passages. Snuff
and many other articles used for catarrh, produce more disease than
they remove.

  -=-=-=-=-=-=-=-=-=-=-=-=

889. On what does acuteness of smell depend? What effect has snuff
when introduced into the nose? What is said of chronic catarrh?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XLIV.

SENSE OF VISION.


890. This sense contributes more to the enjoyment and happiness of man
than any other of the senses. By it we perceive the form, color,
volume, and position of objects that surround us. The eye is the organ
of sight, or vision, and its mechanism is so wonderful, that it not
only proves the existence of a great First Cause, but perhaps, more
than other organs, the design of the Creator to mingle pleasure with
our existence.


ANATOMY OF THE ORGANS OF VISION.

891. The apparatus of vision consists of the _Op´tic Nerve_, the
_Globe_ and _Muscles_ of the eye, and its _Protecting Organs_.

892. The OPTIC NERVE arises by two roots from the central portion of
the base of the brain. The two nerves approach each other, as they
proceed forward, and some of the fibres of each cross to the nerve of
the opposite side. They then diverge, and enter the globe of the eyes
at their back part, where they expand, and form a soft, whitish
membrane.

893. The GLOBE, or ball of the eye, is an optical instrument of the
most perfect construction. The sides of the globes are composed of
_Coats_, or membranes. The interior of the globe is filled with
refracting _Humors_, or _me´di-ums_.

  -=-=-=-=-=-=-=-=-=-=-=-=

890. Which sense contributes most to the enjoyment of man? What do we
perceive by this sense? What is said of the mechanism of the eye?
891-916. _Give the anatomy of the organs of vision._ 891. Of what does
the apparatus of vision consist? 892. Describe the optic nerve. 893.
Describe the globe of the eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

894. The COATS are three in number: 1st. The _Scle-rot´ic_ and
_Corn´e-a_. 2d. The _Cho´roid_, _Iris_, and _Cil´ia-ry processes_. 3d.
The _Ret´i-na_.

895 The HUMORS are also three in number: 1st. The _A´que-ous_, or
watery. 2d. The _Crys´tal-line_, (lens.) 3d. The _Vit´re-ous_, or
glassy.

[Illustration: Fig. 137. The second pair of nerves. 1, 1, Globe of the
eye: the one on the left is perfect, but that on the right has the
sclerotic and choroid coats removed, to show the retina. 2, The crossing
of the optic nerve. 5, The pons varolii. 6, The medulla oblongata. 7, 8,
9, 10, 11, 12, 13, The origin of several pairs of cranial nerves.]

896. The SCLEROTIC COAT is a dense, fibrous membrane and invests about
four fifths of the globe of the eye. It gives form to this organ, and
serves for the attachment of the muscles that move the eye in various
directions. This coat, from the brilliancy of its whiteness, is known
by the name of "the white of the eye." Anteriorly, the sclerotic coat
presents a bevelled edge, which receives the cornea in the same way
that a watch-glass is received by the groove in its case.

  -=-=-=-=-=-=-=-=-=-=-=-=

894. Name the coats of the eye. 895. Name the humors of the eye.
Explain fig. 137. 896. Describe the sclerotic coat.

  -=-=-=-=-=-=-=-=-=-=-=-=

897. The CORNEA is the transparent projecting layer, that forms the
anterior fifth of the globe of the eye. In form, it is circular,
convexo-concave, and resembles a watch-glass. It is received by its
edge, which is sharp and thin, within the bevelled border of the
sclerotic, to which it is firmly attached. The cornea is composed of
several different layers; its blood-vessels are so small that they
exclude the red particles altogether, and admit nothing but serum.

898. The CHOROID COAT is a vascular membrane, of a rich chocolate-brown
color upon its external surface, and of a deep black color within. It
is connected, externally, with the sclerotic, by an extremely fine
cellular tissue, and by the passage of nerves and vessels; internally,
it is in contact with the retina. The choroid membrane is composed of
three layers. It secretes upon its internal surface a dark substance,
called _pig-ment´um ni´grum_, which is of great importance in the function
of vision.

899. The IRIS is so called from its variety of color in different
persons. It forms a partition between the anterior and posterior
chambers of the eye, and is pierced by a circular opening, which is
called the _pu´pil_. It is composed of two layers. The radiating
fibres of the anterior layer converge from the circumference to the
centre. Through the action of these radiating fibres the pupil is
dilated. The circular fibres surround the pupil, and by their action
produce contraction of its area. The posterior layer is of a deep
purple tint, and is called _u-ve´a_, from its resemblance in color to
a ripe grape.

  -=-=-=-=-=-=-=-=-=-=-=-=

How are this coat and the cornea united? 897. Describe the cornea.
898. What is the color of the external surface of the choroid coat? Of
the internal? How is it connected externally? How internally? What
does this membrane secrete upon its internal surface? 899. Describe
the iris. Of how many layers of fibres is the iris composed? What is
the function of the radiating fibres? Of the circular?

  -=-=-=-=-=-=-=-=-=-=-=-=

900. The CILIARY PROCESSES consist of a number of triangular folds,
formed, apparently, by the plaiting of the internal layer of the
choroid coat. They are about sixty in number. Their external border is
continuous with the internal layer of the choroid coat. The central
border is free, and rests against the circumference of the crystalline
lens. These processes are covered by a layer of the pigmentum nigrum.

[Illustration: Fig. 138. A view of the anterior segment of a transverse
section of the globe of the eye, seen from within. 1, The divided edge of
the three coats--sclerotic, choroid, and retina. 2, The pupil. 3, The
iris: the surface presented to view in this section being the uvea. 4,
The ciliary processes. 5, The scalloped anterior border of the retina.]

901. The RETINA is composed of three layers: The external; middle, or
nervous; and internal, or vascular. The external membrane is extremely
thin, and is seen as a flocculent film, when the eye is suspended in
water. The nervous membrane is the expansion of the optic nerve, and
forms a thin, semi-transparent, bluish-white layer. The vascular
membrane consists of the ramifications of a minute artery and its
accompanying vein. This vascular layer forms distinct sheaths for the
nervous papillæ, which constitute the inner surface of the retina.

  -=-=-=-=-=-=-=-=-=-=-=-=

900. How are the ciliary processes formed? What does fig. 138 exhibit?
901. Of how many layers is the retina composed? Describe the external
layer. The nervous layer.

  -=-=-=-=-=-=-=-=-=-=-=-=

902. The AQUEOUS HUMOR is situated in the anterior and posterior
chambers of the eye. It is an albuminous fluid, having an alkaline
reaction. Its specific gravity is a very little greater than distilled
water. The anterior chamber is the space intervening between the
cornea, in front, and the iris and pupil, behind. The posterior
chamber is the narrow space, less than half a line in depth, bounded
by the posterior surface of the iris and pupil, in front, and by the
ciliary processes and crystalline lens, behind. The two chambers are
lined by a thin layer, the secreting membrane of the aqueous humor.

903. The CRYSTALLINE HUMOR, or lens, is situated immediately behind
the pupil, and is surrounded by the ciliary processes. This humor is
more convex on the posterior than on the anterior surface, and, in
different portions of the surface of each, the convexity varies from
their oval character. It is imbedded in the anterior part of the
vitreous humor, from which it is separated by a thin membrane, and is
invested by a transparent elastic membrane, called the capsule of the
lens. The lens consists of concentric layers, disposed like the coats
of an onion. The external layer is soft, and each successive one
increases in firmness until the central layer forms a hardened
nucleus. These layers are best demonstrated by boiling, or by
immersion in alcohol, when they separate easily from each other.

_Observations._ 1st. The lens in the eye of a fish is round, like a
globe, and has the same appearance, when boiled, as the lens of the
human eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

The vascular layer. 902. Where is the aqueous humor situated? What
part of the eye is called the anterior chamber? The posterior chamber?
With what are the chambers lined? 903. Where is the crystalline humor
situated? With what is it surrounded? Of what does the lens consist?
How are these layers best demonstrated? What is produced when the
lens, or its investing membrane, is changed in structure?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. When the crystalline lens, or its investing membrane, is changed
in structure, so as to prevent the rays of light passing to the
retina, the affection is called a _cataract_.

[Illustration: Fig. 139. A section of the globe of the eye. 1, The
sclerotic coat. 2, The cornea (This connects with the sclerotic coat by a
bevelled edge.) 3, The choroid coat. 6, 6, The iris. 7, The pupil. 8, The
retina. 10, 11, 11, Chambers of the eye that contain the aqueous humor.
12, The crystalline lens. 13, The vitreous humor. 15, The optic nerve.
16, The central artery of the eye.]

904. The VITREOUS HUMOR forms the principal bulk of the globe of the
eye. It is an albuminous fluid, resembling the aqueous humor, but is
more dense, and differs from the aqueous in this important particular,
that it has not the power of re-producing itself. If by accident it is
discharged, the eye is irrecoverably lost; while the aqueous humor may
be let out, and will be again restored. It is enclosed in a delicate
membrane, called the _hy´a-loid_, which sends processes into the
interior of the globe of the eye, forming the cells in which the humor
is retained.

  -=-=-=-=-=-=-=-=-=-=-=-=

904. Describe the vitreous humor. How does this humor differ from the
aqueous? What membrane encloses the vitreous humor?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ The structure of this organ can be seen by first
freezing the eye of a sheep or an ox; it then can be cut in various
directions, and each part separately examined.

905. The MUSCLES of the eye are six in number. They are attached, at
one extremity, to the bones of the orbit behind the eye; at the other
extremity, they are inserted by broad, thin tendons, near the junction
of the cornea with the sclerotic coat. The white, pearly appearance of
the eye is caused by these tendons.

[Illustration: Fig. 140. A view of the eye and its muscles. _a_, _b_,
_c_, _d_, _e_, Five of these muscles. _f_, The optic nerve. G, The
trochlea, or pulley over which one of the muscles passes. The bone is
seen above and below the eye.]

_Observation._ If the external muscle is too short, the eye is turned
out, producing the "wall eye." If the internal muscle is contracted,
the eye is turned inward toward the nose. It is then called a "cross
eye."

  -=-=-=-=-=-=-=-=-=-=-=-=

905. How many muscles has the eye? Give their attachments. What causes
the pearly appearance of the eye? What does fig. 140 represent? What
is the effect if the external muscle is contracted? The internal
muscle?

  -=-=-=-=-=-=-=-=-=-=-=-=

906. The PROTECTING ORGANS are the _Or´bits_, _Eyebrows_, _Eyelids_,
and _Lach´ry-mal Apparatus_.

907. The ORBITS are deep, bony sockets, in which the globes of the
eyes are situated. They have the form of a cone, the base of which is
open and directed forward. The bottom of the orbits is pierced by a
large hole which gives passage to the optic nerve. These cavities are
lined with a thick cushion of fat, in order that the eyes may move in
all directions, with perfect freedom and without friction.

908. The EYEBROWS are two projecting arches of integument, covered
with short, thick hairs, which form the upper boundary of the orbits.
The eyebrows are so arranged that they prevent the moisture that
accumulates on the forehead, in free perspiration, from flowing into
the eye, and also shade these organs from too vivid light.

909. The EYELIDS are two movable curtains placed in front of the eye.
They have a delicate skin on the outside, muscular fibres beneath, and
a narrow cartilage on their edges, which tends to preserve the shape
of the lid. Internally, they are lined by a smooth membrane, which is
reflected over the front of the eye upon the sclerotica. This membrane
is called the _con-junc-ti´va_. It secretes the fluid that moistens
and lubricates the eye, and which causes the eyelids to open and shut
without friction.

_Observation._ When the portion of this membrane that is reflected
over the globe of the eye, is inflamed, there is frequently a
deposition of whitish material, called lymph. This accounts for the
films, opacities, and white spots seen upon the eye after the
inflammation has subsided.

  -=-=-=-=-=-=-=-=-=-=-=-=

906. Name the protecting organs of the eye. 907. Describe the orbits.
How are the movements of the eye facilitated? 908. Describe the
eyebrows. What does this arrangement prevent? 909. Describe the
eyelids. What is the use of the conjunctiva? How are the white spots
frequently seen upon the eye accounted for?

  -=-=-=-=-=-=-=-=-=-=-=-=

910. There are found several small glands on the internal surface of
the cartilage, which have the appearance of parallel strings of
pearls. They open by minute apertures upon the edges of the lids. The
secretion from these glands prevents the edges of the eyelids from
being united during sleep.

911. The edges of the eyelids are furnished with a triple row of long,
thick hairs, called _eyelashes_, which curve upward from the upper
lid, and downward from the lower, so that they may not interlace with
each other in the closure of the eyelids. These appendages of the eye,
by closing, not only protect it from moisture, but from dust,
particularly during sleep. They likewise, by their movements in
opening and shutting, spread the lubricating fluid equally over the
eye.

912. The LACHRYMAL APPARATUS, which secretes the tears, consists of
the _Lachrymal Gland_ with its ducts, _Lachrymal Canals_, and the
_Nasal Duct_.

913. The LACHRYMAL GLAND is situated at the upper and outer angle of
the orbit. It is about three quarters of an inch in length, flattened
and oval in shape, and occupies a depression in the orbital plate of
the frontal bone. Ten or twelve small ducts pass from this gland, and
open upon the upper eyelid, where they pour upon the conjunctiva the
lachrymal fluid, or tears. This secretion is maintained while we are
asleep, as well as when we are awake. The eye from this cause is kept
constantly moist.

914. The LACHRYMAL CANALS commence at minute openings upon the free
borders of each eyelid, near the internal angle of the eye, by two
small orifices, called _punc´ta lach-ry-ma´li-a_, (tear points.) Each
of these points communicate with the sac at the upper part of the
nasal duct.

  -=-=-=-=-=-=-=-=-=-=-=-=

910. What are found on the internal surface of the cartilage of the
eyelids? Where do they open, and what is their use? 911. With what are
the edges of the eyelids furnished? What are their uses? 912. Of what
does the lachrymal apparatus consist? 913. Describe the lachrymal
gland. How many ducts pass from this gland, and what do they convey to
the eye? Why is the eye constantly moist? 914. Where do the lachrymal
canals commence?

  -=-=-=-=-=-=-=-=-=-=-=-=

915. The NASAL DUCT is a short canal, about three quarters of an inch
in length, directed downward and backward to the inferior channel of
the nose, where it terminates by an expanded orifice.

[Illustration: Fig. 141. 1, The lachrymal gland. 2, Ducts leading from
the lachrymal gland to the upper eyelid. 3, 3, The puncta lachrymalia. 4,
The nasal sac. 5, The termination of the nasal duct.]

916. The fluid (tears) secreted by the lachrymal gland, is conveyed to
the eye by the small ducts before described. It is then imbibed by the
puncta lachrymalia, and carried by the lachrymal canals into the
lachrymal sac, from which it is passed to the nasal cavities by the
nasal ducts.

  -=-=-=-=-=-=-=-=-=-=-=-=

What are they called? With what do they communicate? 915. Describe the
nasal duct. 916. How are the tears conveyed from the lachrymal gland
to the nose?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XLV.

PHYSIOLOGY OF THE ORGANS OF VISION.


917. To comprehend the theory of vision, it is not sufficient to know
the structure of the eye. We must be familiar with some of the
properties of a subtile fluid, which is constantly emanating from all
luminous bodies, called _light_.

918. It is the province of natural philosophy, rather than physiology,
to enter minutely upon the properties of light. It may be observed,
however, that, when light passes through any medium of the same
density, the rays are in straight lines; but, when it passes from one
medium into another of different density, it is refracted, or
turned from a straight course, unless it strikes the medium in a
perpendicular direction--then light passes through without a change
of direction.

919. When a ray of light meets with a body, it either passes through
it, or is reflected by it, or it may be absorbed. Again, in proportion
as the rays of light become distant from the body from which they
emanate, they diverge one from the other. In accordance with the laws
of optics, the rays of light, in passing through an optical instrument
like the eye, must cross each other, and thus produce an inverted
image of the object from which the rays proceed. With the general
view of the structure of the eye, we will now examine the use of each
part in the function of vision.

  -=-=-=-=-=-=-=-=-=-=-=-=

917-933. _Give the physiology of the organs of vision._ 917. What is
necessary in order to understand the theory of vision? 918. When light
passes through a medium of the same density, in what direction will be
its rays? Of a different density? What exception? 919. When light
meets with a body, what takes place? What is said in reference to rays
of light in passing through the eye?

  -=-=-=-=-=-=-=-=-=-=-=-=

920. The sclerotic coat not only gives form to the body of the eye,
but protection to the interior and more delicate parts. The choroid
coat seems to be chiefly composed of a tissue of nerves and minute
blood-vessels; the latter give nourishment to the different parts of
the eye. One of the uses of this coat is, to absorb the rays of light
immediately after they have passed through the retina. This is
effected by the black pigment that lines its inner surface. Were it
not for this provision, light would be too intense, and vision
indistinct.

_Observation._ In albinos, where there is an absence of the black
pigment, the rays of light traverse the iris, and even the choroid
coat, and so overwhelm the eye with light, that their vision is quite
imperfect, except in the dimness of evening, or at night. In the
manufacture of optical instruments, care is taken to color their
interior black, for the same object, namely, the absorption of
scattered rays.

921. The iris, by means of its powers of expansion and contraction,
regulates the quantity of light admitted through the pupil. If the
iris is thin, and the rays of light pass through its substance, they
are immediately absorbed by the uvea, and, if that layer be
insufficient, they are taken up by the black pigment of the choroid
coat.

_Observation._ When we look toward the bottom of the eye, the pupil
appears like a black spot, instead of an opening. This is caused by
seeing the black pigment through the retina and humors of the eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

920. What is the use of the sclerotic coat? Of what is the choroid
coat chiefly composed? What is the use of this coat? How is it
effected? What is said of albinos? What care is taken in the
manufacture of optical instruments? 921. What is the use of the iris?
When we look toward the bottom of the eye, why does the pupil look
like a black spot, instead of an opening?

  -=-=-=-=-=-=-=-=-=-=-=-=

922. The cornea, and the aqueous, crystalline, and vitreous humors,
are transparent; so that rays of light traverse these parts of the
eye, and fall upon the retina. The office of these humors and the
cornea is to refract the rays of light in such proportion as to direct
the image in the most favorable manner upon the retina.

923. The office of the retina is to receive the impression of the rays
of light which leave an object at which we look, and it is upon it
that a small but very clear image of that object is formed. The
impression thus produced by the reflected light is transmitted by the
optic nerve to the brain, which receives the sensation. This
constitutes vision.

924. The optic nerve has but one function, that of sight. Sensibility
is conferred on this organ by a large branch from the fifth pair of
nerves, which ramifies upon the different parts of the eye and its
appendages. These parts, however, receive some nervous filaments from
the seventh pair.

_Observations._ 1st. The large number of sensitive nervous filaments
renders the visual organ very impressible to bodies that cause
irritation, as dust, or intense light. This compels us to use due care
to shield the eye from the influence of agents that would impair or
destroy vision.

2d. Although particles of dust, when in contact with the delicate
parts of the eye, induce severe pain, yet these parts may be cut in
surgical operations, and the patient's sufferings are not as great as
when an incision is made in the skin to remove a small tumor.

925. Different degrees of density, as already mentioned, modify the
refractory power of any transparent medium. It is found, on
examination, that the cornea, the vitreous, the crystalline, and the
aqueous humors, have each, severally, various degrees of density: and
that the crystalline lens, at its circumference, is less dense than at
its centre. These circumstances modify the direction of the refraction
of the rays of light, in their passage from the cornea to the retina.

  -=-=-=-=-=-=-=-=-=-=-=-=

922. What is the use of the cornea, aqueous, crystalline, and
vitreous humors? 923. What is the office of the retina? 924. What is
the function of the optic nerve? How is sensibility conferred on
this organ? Give the 1st observation in this connection. The 2d
observation.

  -=-=-=-=-=-=-=-=-=-=-=-=

926. The refracting powers of the plane, convex, concave, plano-convex,
plano-concave, and concavo-convex lenses,[22] are different. The
cornea and aqueous humors are convexo-concave, the vitreous humor is
concavo-convex, while the crystalline humor is a convexo-convex medium.
(Fig. 139.)

  [22] The refracting character of differently-formed lenses is
       illustrated in the works on Natural Philosophy, to which the
       pupil is referred.

[Illustration: Fig. 142. The forms of the different lenses. 1, A plane
lens. 2, A globe lens. 3, A convexo-convex lens. 4, A plano-convex lens.
5, A concavo-concave lens. 6, A plano-concave lens. 7, Meniscus. 8, A
concavo-convex lens.]

  -=-=-=-=-=-=-=-=-=-=-=-=

925. Have the cornea and the humors of the eye different degrees of
density? What is said of the crystalline lens? What effect has the
different density of the parts of the eye upon the light admitted to
this organ? 926. What kind of lenses do the humors exhibit? 927. What
modifies the refracting powers of transparent mediums? How does this
principle apply to the humors of the eye?

  -=-=-=-=-=-=-=-=-=-=-=-=

927. The different degrees of convexity or concavity also modify the
refracting character of transparent mediums. The crystalline lens is
of different degrees of convexity on its two sides. The convex
surfaces of the aqueous and vitreous humors are segments of circles,
of different diameters from their concave surfaces. (Fig. 139.) All
these circumstances still further influence the refracting character
of the visual organ. The achromatic arrangement of the transparent
refracting mediums of the eye, remedies the aberration of refraction
in the different portions of the eye.

928. Again, the refracting power of lenses is modified by their
convexity or concavity. The more convex a lens is, the shorter the
distance from the refracting medium, where the different refracted
rays converge to a focus. To adapt the eye to view objects at
different distances, requires a change in the refracting power of some
of the transparent mediums of the eye.

929. Both surfaces of the crystalline lens are oval, not spherical,
and the refraction of the rays of light is mainly effected in this
portion of the eye. Change the inclination of this lens, so that
different portions of its anterior surface shall be directly behind
the pupil, and its refracting power is increased or diminished, as the
surface presented is more or less convex.

930. To view objects at a distance, a less convex lens is needed than
in examining articles very near the eye; and this organ, from its
structure, has the power of adaptation to different distances. It is
supposed that the muscular substance of the ciliary body and processes
changes, by its contraction, the inclination of the crystalline lens.
Without this, or some other adapting power, a picture of objects at
different distances would not be formed upon the retina, and the
vision of every person would be defective, except in reference to
objects at certain definite distances from the eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

928. What modifies the refracting power of lenses? What is necessary
to adapt the eye to view objects at different distances? 929. Where is
the refraction of the rays of light mainly effected? 930. When we view
objects at a distance, what kind of lens is required? Has the eye the
power of adapting itself to different distances? How is it effected?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ It is well known that a separate image is formed on
each eye, and, if they are not in the same direction, the objects will
appear double. This is proved by pressing one eye, so that the rays of
light cannot enter it in the same direction as they do in the other;
consequently, the vision is double.

931. By the action of the muscles of the eye, it is turned in
different directions, so that objects can be examined upon each side,
as well as in front, without turning the body. By the slight or
intense action of the straight muscles, the eye is more or less
compressed, and the form of the globe is changed, together with the
relative positions of the different humors. This modification also
adapts the eye to view objects at different distances.

[Illustration: Fig. 143. 1, A pen, an inverted image of which is painted
on the retina of the eye, at 2. The image of all objects upon the
expansion of the optic nerve, is inverted by the crossing of the rays of
light from objects as they traverse the pupil.]

_Observation._ If the eye is fixed for a time on some object which is
distinguished with difficulty, there is a painful sensation, similar
to that experienced by other muscles of the body when used too long.
This is called "straining the eye."

932. When the refraction of the rays of light is too great, as in
over-convexity of the cornea, or the crystalline lens, or the
vitreous humor, or all of them, the image is formed a little in
front of the retina. Persons thus affected cannot see distinctly,
except at a very short distance. This infirmity is called _near_, or
_short-sightedness_. This defect is in a great measure obviated by
the use of concave glasses, which scatter the luminous rays, and thus
counterbalance the too strong refracting force of the eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does fig. 143 represent? 931. Why can we see objects at the side
as well as in front of the eye, without turning the body? What is the
effect when the eye is fixed on an object that is indistinctly seen?

  -=-=-=-=-=-=-=-=-=-=-=-=

933. When the different parts of the eye are not sufficiently convex,
the image is formed beyond the retina, and thus only distant objects
are distinctly seen. This defect is called _long-sightedness_. The
feebleness in the refracting power of the eye may be caused by
disease; but usually it is a consequence of old age, and is remedied
by wearing spectacles with convex glasses.


HYGIENE OF THE ORGANS OF VISION.

934. _The eye, like other organs of the body, should be used, and then
rested._ If we look intently at an object for a long time, the eye
becomes wearied, and the power of vision diminished. The observance of
this rule is particularly needful to those whose eyes are weak, and
predisposed to inflammation. On the contrary, if the eye is not called
into action, its functions are enfeebled.

935. _Sudden transitions of light should be avoided._ The iris
enlarges or contracts, as the light that falls upon the eye is faint
or strong; but the change is not instantaneous. Hence the imperfect
vision in passing from a strong to a dim light, and the overwhelming
sensation experienced on emerging from a dimly-lighted apartment to
one brilliantly illuminated. A common cause of _am-aur-o´sis_, or
paralysis of the retina, is, using the eye for a long time in a very
intense light.

  -=-=-=-=-=-=-=-=-=-=-=-=

932. What is short-sightedness? How is the defect remedied? 933. What
is long-sightedness? How is the defect remedied? 934-942. _Give the
hygiene of the organs of vision._ 934. Do the same principles apply to
the use of the eye as to other organs? What is the effect if the eye
is fixed intently on an object for a long time? What results if the
eye is not called into action? 935. Why should sudden transitions of
light be avoided?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Note._ Let the anatomy and physiology of the eye be reviewed from
figs. 139 and 143, or from anatomical outline plate No. 10.

936. _Long-continued oblique positions of the eye should be avoided,
when viewing objects._ If the eye is turned obliquely for a long time
in viewing objects, it may produce an unnatural contraction of the
muscle called into action. This contraction of the muscle is termed
_stra-bis´mus_, or cross-eye. The practice of imitating the appearance
of a person thus affected, is injudicious, as the imitation, designed
to be temporary, may become permanent.

_Observation._ The vision of a "cross-eye" is always defective. In
general, only one eye is called into action, in viewing the object to
which the mind is directed. This defect can be remedied by a surgical
operation, which also corrects the position of the eye.

937. _Children should be trained to use the eye upon objects at
different distances._ This is necessary, in order that the vision may
be correct when objects at various distances are viewed. Any action
unnatural to the muscles, if frequently repeated, may and will modify
the character and action of the parts so operated upon. If a limb, as
the arm, be kept flexed for a long time, one set of muscles will be
relaxed and elongated, and another will be shortened, and its
contractile power will be increased. The same principle is true of the
eye.

  -=-=-=-=-=-=-=-=-=-=-=-=

What causes palsy of the retina? 936. Why should we avoid oblique
positions of the eye in viewing objects? What is said of the practice
of imitating persons thus affected? What is said in reference to the
vision of a "cross-eye"? 937. Why should children be trained to use
the eye upon objects at different distances? What is the effect if an
unnatural action of the muscles is frequently repeated? Does the same
principle apply to the eye?

  -=-=-=-=-=-=-=-=-=-=-=-=

938. In viewing objects very near the eye, the ciliary processes are
called into action to produce a proper inclination of the crystalline
lens, so that the rays of light may be properly refracted to form a
perfect image on the retina. In looking at objects at a great
distance, the ciliary processes are called into a different action, to
produce a different inclination of the lens. Let either of these
actions be repeated, again and again, for weeks and months, and they
will become natural, and the acquired inclination will be permanent.

939. From the preceding principle, a person becomes short or long
sighted, as the objects to which the eye is usually directed are near
or remote. This is one reason why scholars, watchmakers, and
artisans, who bring minute objects near the eye to examine them,
are short-sighted, and why hunters and sailors, who are habituated
to view objects at a distance, are long-sighted.

_Observation._ In the management of children, whether in the nursery
or school-room, it is very important that their books, or articles
upon which they may labor, should be held at an appropriate distance
from the eye. Were this attended to by the parent or instructor, we
should not see so many persons with defective vision.

940. Cleanliness, as well as the health of the eye, require that it be
bathed every morning with pure water, either cold or tepid,
accompanied with as little rubbing or friction as possible. In all
instances, the secretion from the lachrymal glands, that sometimes
collects at the angle of the eye, should be removed, as it contains
saline matter.

941. When small particles, or dust, get upon the eye, they produce
much inconvenience, which is often increased by harsh attempts to
remove them. The individual should be placed before a strong
light, the lids held open with one hand, or by another person, and
the particles removed with the corner of a fine linen or silk
handkerchief.

  -=-=-=-=-=-=-=-=-=-=-=-=

938. What is the effect of repeatedly using the eye in one direction?
939. Why are artisans and scholars generally short-sighted? Why are
sailors and hunters long-sighted? How can defective vision in a great
degree be prevented? 940. What reasons are there for bathing the eye?
941. How can dust and other small particles be removed from the eye?

  -=-=-=-=-=-=-=-=-=-=-=-=

942. Sometimes the substance is concealed under the upper eyelid, and
it may then be exposed by turning back the lid in the following
manner: Take a knitting-needle, or small, slender piece of stick,
which is perfectly smooth, and place it over the upper lid, in contact
with, and just under the edge of the orbit; then, holding it firmly,
seize the eyelashes with the fingers of the disengaged hand, and
gently turn the lid back over the stick or needle. The inner side of
the lid can then be examined, and any substance removed that may have
been there concealed. Too many trials ought not to be made, if
unsuccessful, as much inflammation may be induced; but a surgeon
should be consulted as soon as possible.

_Observation._ Eyestones ought never to be placed in the eye, as they
often cause more pain and irritation than the evil which they are
intended to remedy.

  -=-=-=-=-=-=-=-=-=-=-=-=

942. How removed from the upper eyelid? Why should not eyestones be
used?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XLVI.

THE SENSE OF HEARING.


943. The sense of hearing is next in importance to that of vision.
Through this sense we are enabled to perceive sounds, that not only
subserve to our comfort and pleasure, but are instrumental in
promoting our intellectual enjoyments. The organ of hearing, or the
ear, is one of the most complicated in the human body.


ANATOMY OF THE ORGANS OF HEARING.

944. The EAR is composed of three parts: 1st. The _External Ear._ 2d.
The _Tym´pan-um_, or middle ear. 3d. The _La´by-rinth_, or internal
ear.

945. The EXTERNAL EAR is composed of two parts: The _Pin´na_,
(pavilion of the ear,) and the _Me-a´tus Aud-it-o´ri-us Ex-ter´nus_,
(auditory canal.)

946. The PINNA is a cartilaginous plate which surrounds the entrance
of the auditory canal. It presents many ridges and furrows, arising
from the folds of the cartilage that form it.

_Observation._ The pinna, in many animals, is movable; in those that
pursue their prey, it is generally directed forward; in timid animals,
as the hare and rabbit, it is directed backward. In man, this part is
but slightly under the control of the will.

  -=-=-=-=-=-=-=-=-=-=-=-=

943. What is said of the importance of hearing? Is the ear complicated
in its structure? 944-962. _Give the anatomy of the organs of
hearing._ 944. Of how many parts is the ear composed? Name them. 945.
Give the parts of the external ear. 946. Describe the pinna. What is
said in reference to the pinna of many animals?

  -=-=-=-=-=-=-=-=-=-=-=-=

947. The MEATUS AUDITORIUS is a canal partly cartilaginous, and partly
bony, about an inch in length, which extends inward from the pinna to
the _Mem´bra-na Tym´pan-i_, (drum of the ear.) It is narrower in the
middle than at the extremities. It is lined by an extremely thin pouch
of cuticle, which, when withdrawn, after maceration, preserves the
form of the canal. Some stiff, short hairs are also found in the
interior of the channel, which stretch across the tube, and prevent
the ingress of insects. Beneath the cuticle are a number of small
follicles, which secrete the wax of the ear.

[Illustration: Fig. 144. A representation of the four bones of the ear.
The smallest is highly magnified. This bone is early matured, and in the
adult it becomes united with the incus. These bones are retained in their
places and moved by three ligaments and four muscles.]

948. The MEMBRANA TYMPANI is a thin, semi-transparent membrane, of an
oval shape. It is about three eighths of an inch in diameter, and is
inserted into a groove around the circumference of the meatus, near
its termination. This membrane is placed obliquely across the area of
that tube. It is concave toward the meatus, and convex toward the
tympanum.

949. The TYMPANUM consists of an irregular bony cavity, situated
within the temporal bone. It is bounded externally by the membrana
tympani; internally by its inner wall; and in its circumference by the
petrous portion of the temporal bone and mastoid cells. The tympanum
contains four small bones, called the _os-sic´u-la au-di´tus_. These
are named separately, the _mal´le-us_, _in´cus_, _sta´pes_, and
_or-bic´u-lar_.

  -=-=-=-=-=-=-=-=-=-=-=-=

947. What is the meatus auditorius? What is found in this canal? What
is their use? Where is the wax of the ear secreted? 948. Describe the
membrana tympani. 949. Where is the tympanum situated?

  -=-=-=-=-=-=-=-=-=-=-=-=

950. There are ten openings in the middle ear; five large and five
small. The larger openings are, the _Me-a´tus Aud-it-o´ri-us
Ex-ter´nus_, _Fe-nes´tra O-va´lis_, (oval window,) _Fe-nes´tra
Ro-tun´da_, (round window,) _Mas´toid Cells_, and _Eu-sta´chi-an
Tube_.

[Illustration: Fig. 145. A representation of the pinna, meatus, membrana
tympani, bones of the ear, and semicircular canals. _a_, The pinna. _c_,
The meatus auditorius externus. _g_, The membrana tympani. _k_, The
tympanum. _e_, The bones of the ear. _b_, The semicircular canals. _f_,
The cochlea. _h_, The vestibule. _i_, The Eustachian tube. _d_, The
auditory nerve.]

951. The FENESTRA OVALIS is the opening of communication between the
tympanum and the vestibule. It is closed by the foot of the stapes, or
bone of the ear, and by the lining membrane of both cavities.

952. The FENESTRA ROTUNDA serves to establish a communication between
the tympanum and the cochlea. it is closed by a proper membrane, as
well as by the lining of both cavities.

  -=-=-=-=-=-=-=-=-=-=-=-=

What does this cavity contain? 950. How many openings in the tympanum?
Explain fig. 145. 951. Describe the fenestra ovalis. 952. The fenestra
rotunda.

  -=-=-=-=-=-=-=-=-=-=-=-=

953. The MASTOID CELLS are very numerous, and occupy the whole of the
interior of the mastoid process of the temporal bone, and part of the
petrous bone. They communicate, by a large, irregular opening, with
the upper and posterior circumference of the tympanum.

[Illustration: Fig. 146. A view of the labyrinth laid open. This figure
is highly magnified. 1, 1, The cochlea. 2, 3, Two channels, that wind two
and a half turns around a central point, (5.) 7, The central portion of
the labyrinth, (vestibule.) 8, The foramen rotundum. 9, The fenestra
ovalis. 11, 12, 13, 14, 15, 16, 17, 18, The semicircular canals. The
cochlea and semicircular canals open into the vestibule.]

954. The EUSTACHIAN TUBE is a canal of communication, extending
obliquely between the pharynx and the anterior circumference of the
tympanum. In structure it is partly fibro-cartilaginous and partly
bony. It is broad and expanded at its pharyngeal extremity, and narrow
and compressed at the tympanum.

  -=-=-=-=-=-=-=-=-=-=-=-=

953. Where are the mastoid cells? Explain fig. 146. 954. Describe the
Eustachian tube.

  -=-=-=-=-=-=-=-=-=-=-=-=

955. The small openings of the middle ear are for the entrance and
exit of the chorda tympani, (a small nerve that crosses the tympanum,)
and for the exit of the muscles that act upon the membrana tympani and
bones of the ear.

956. The LABYRINTH consists of a membranous and a bony portion. The
bony labyrinth presents a series of cavities which are channelled
through the substance of the petrous bone. It is situated between the
cavity of the tympanum and the _Aud´it-o-ry Nerve_. The labyrinth is
divided into the _Ves´ti-bule_, _Sem-i-cir´cu-lar Canals_, and
_Coch´le-a_.

957. The VESTIBULE is a small, three-cornered cavity, situated
immediately within the inner wall of the tympanum.

958. The SEMICIRCULAR CANALS are three bony passages which communicate
with the vestibule, into which two of them open at both extremities,
and the third at one extremity.

959. The COCHLEA forms the anterior portion of the labyrinth. It
consists of a bony and gradually tapering canal, about one and a half
inches in length, which makes two turns and a half, spirally, around a
central axis, called the _mo-di´o-lus_. The modiolus is large near its
base, where it corresponds with the first turn of the cochlea, and
diminishes in diameter toward its extremity.

960. The interior of the canal of the cochlea is partially divided
into two passages, by means of a bony and membranous plate. At the
extremity of the modiolus, the two passages communicate with each
other. At the other extremity, one opens into the vestibule; the other
into the tympanum, by the foramen rotundum. The internal surface of
the bony labyrinth is lined by a fibro-serous membrane.

  -=-=-=-=-=-=-=-=-=-=-=-=

955. What passes through the small openings of the middle ear? 956. Of
what does the labyrinth consist? Give the parts of the internal ear.
957. Describe the vestibule. 958. What is said of the semicircular
canals? 959. Why is the cochlea so called? Of what does it consist?
960. How is the interior of the canal of the cochlea divided? Where do
they communicate with each other?

  -=-=-=-=-=-=-=-=-=-=-=-=

961. The membranous labyrinth is smaller in size, but a perfect
counterpart, with respect to form, of the bony vestibule, cochlea, and
semicircular canals. Within this labyrinth are two small, elongated
sacs, which are filled with a fluid.

[Illustration: Fig. 147. A view of the auditory nerve. 1, The spinal
cord. 2, The medulla oblongata. 3, The lower part of the brain. 4, The
auditory nerve. 5, A branch to the semicircular canals. 6, A branch to
the cochlea.]

962. The AUDITORY NERVE enters the temporal bone upon its internal
surface, and divides into two branches, at the bottom of the cavity of
the internal ear. These branches enter the structure of the elongated
sacs and membranous labyrinth, radiating in all directions, and
finally, they terminate upon the inner surface of the membrane, in
minute papillæ, resembling those of the retina.

  -=-=-=-=-=-=-=-=-=-=-=-=

By what is the internal labyrinth lined? 961. Describe the membranous
labyrinth. What does fig. 147 represent? 962. Where does the auditory
nerve enter and divide? Where do the branches of the auditory nerve
enter and terminate?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XLVII.

PHYSIOLOGY OF THE ORGANS OF HEARING.


963. HEARING is that function by which we obtain a knowledge of the
vibratory motions of bodies, which constitute sounds. The precise
function of all the different parts of the ear is not known.

964. The function of that part of the external ear which projects from
the head is to collect sounds and reflect them into the meatus.

965. The membrana tympani serves to facilitate the transmission of
sounds, and also to moderate their intensity. It is so arranged that
it can be relaxed or tightened.

_Observation._ This membrane, when healthy, has no opening; and it
must be apparent that the apprehension which is often expressed, that
insects will penetrate further, is groundless. The pain is owing to
the extreme sensibility of the membrana tympani.

966. The supposed office of the tympanum is to transmit the vibrations
made on the membrana tympani to the internal ear. This is effected by
the air which it contains, and by the chain of small bones that are
enclosed in this cavity.

967. The use of the Eustachian tube is to admit air into the tympanum,
which renders the pressure on both sides equal, and thus its membrane
is kept in a proper state of tension.

  -=-=-=-=-=-=-=-=-=-=-=-=

963-971. _Give the physiology of the organs of hearing._ 963. What is
hearing? Are the precise functions of the different parts of the ear
known? 964. What is the function of the external ear? 965. Of the
membrana tympani? What observation in reference to this membrane? 966.
What is the supposed office of the middle ear? 967. What is the use of
the Eustachian tube?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Observation._ When near a cannon, or a field-piece, about being
discharged, by opening the mouth the impression upon the auditory
nerve will be diminished, and the unpleasant sensation lessened. This
is the result of the air in the middle ear escaping through the
Eustachian tube, when the vibrations of the membrana tympani are
violent.

[Illustration: Fig. 148. A view of all the parts of the ear. 1, The tube
that leads to the internal ear. 2, The membrana tympani. 3, 4, 5, The
bones of the ear. 7, The central part of the labyrinth, (vestibule.) 8,
9, 10, The semicircular canals. 11, 12, The channels of the cochlea. 13,
The auditory nerve. 14, The channel from the middle ear to the throat,
(Eustachian tube.)]

968. But little is known of the functions of the internal ear; its
parts are filled with a watery fluid, in which the filaments of the
auditory nerve terminate.

  -=-=-=-=-=-=-=-=-=-=-=-=

What observation in this connection? 968. What is the function of the
internal ear?

  -=-=-=-=-=-=-=-=-=-=-=-=

969. Many of the parts just enumerated aid in hearing, but are not
absolutely essential to this sense. But if the vestibule and auditory
nerve are diseased or destroyed, no sound is then perceived. If this
sense is destroyed in early life, the person also loses the power of
articulating words. Hence a man born deaf is always dumb.

970. The transmission of sound through the different parts of the ear
will now be explained by aid of fig. 148. The vibrations of air are
collected by the external ear, and conducted through the tube (1) to
the membrana tympani, (2.) From the membrane vibrations pass along the
chain of bones, (3, 4, 5.) The bone 5 communicates with the internal
ear, (7, 8, 9, 10, 11, 11, 11, 12, 12, 12.) From the internal ear the
impression is transmitted to the brain by the nerve, (13.)

971. The auditory nerve, like the optic, has but one function, that of
special sensibility. The nerves which furnish the ear with ordinary
sensibility, proceed from the fifth pair.


HYGIENE OF THE ORGANS OF HEARING.

972. Hearing, like the other senses, is capable of very great
improvement. By cultivation, the blind are enabled to judge with great
accuracy the distance of bodies in motion, and even the height of
buildings. It is also capable of improvement when all the other senses
are perfect. Thus the Indian will distinguish sounds that are
inaudible to the white man.

  -=-=-=-=-=-=-=-=-=-=-=-=

969. What parts of the ear are essential in order to hear sounds? What
follows loss of hearing? 971. What is the office of the auditory
nerve? What nerves convey ordinary sensibility to the ear? 972-978.
_Give the hygiene of the organs of hearing._ 972. Is this sense
capable of improvement? How does this sense aid the blind? Is it also
capable of improvement when all the other senses are perfect? In whom
is this illustrated?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Note._ Let the anatomy and physiology of the organs of hearing be
reviewed, from fig. 148, or from anatomical outline plate No. 10.

973. Acute hearing requires perfection in the structure and functions
of the different parts of the ear, and that portion of the brain from
which the auditory nerve proceeds. Deafness is by no means unfrequent.
We will now advert to some of the common causes of imperfect hearing.

974. The structure or functional action of the brain may be deranged
by inflammation, by compression, or by debility, and produce deafness.
The first is seen during inflammatory affections of the brain, and in
fevers; the second is seen in accidental injuries of the head; the
third is seen in old age, and after severe diseases of the head, and
fevers. In these cases, applications to, and operations upon, the ear
do no good. The only remedy is to remove, if possible, the diseased
condition of the brain.

975. Imperfect hearing may be produced by the destruction of the
membrana tympani, or removal of the bones of the ear, or the parts
within the labyrinth. In these instances, medical treatment is of no
avail, as the destroyed parts cannot be restored.

976. Hearing may be rendered defective by a diminution of the
vibratory character of the membrana tympani. This may result from a
thickening of this membrane, or from an accumulation of wax upon its
outer surface. The increased thickness is usually the result of
inflammation, either acute or chronic. The proper treatment is such as
is efficient to remove inflammatory action.

_Observations._ 1st. The introduction of heads of pins into the ear is
a frequent cause of chronic inflammation of the membrana tympani.
Hence this practice should never be adopted, and if acquired, should
be abandoned.

  -=-=-=-=-=-=-=-=-=-=-=-=

973. On what does acute hearing depend? 974. State effects on the
hearing in some conditions of the brain. How relieved? 975. Of the
effect on hearing when the bones of the ear or the labyrinth are
destroyed? Is medical treatment of any avail? 976. What conditions of
the drum of the ear may impair hearing? How relieved? What is said of
the introduction of pins to cleanse the ear?

  -=-=-=-=-=-=-=-=-=-=-=-=

2d. The accumulations of viscid wax may be softened by dropping some
animal oil into the ear, and then removing it by ejecting warm soap
suds a few hours subsequent to the use of the oil. This may be
repeated for several successive days.

977. Hearing may be impaired by obstruction of the Eustachian tube.
The closure of this canal diminishes the vibratory character of
the air within the tympanum, in the same manner as closing the
opening in the side of a drum. For the same reason, enlarged
tonsils, inflammation and ulceration of the fauces and nasal
passages during and subsequent to an attack of scarlet fever, and
the inflammation attending the "sore throat" in colds, are common
causes of this obstruction.

978. The treatment of such cases of defective hearing, is to have the
tonsils, if enlarged, removed by a surgeon; for the inflammation and
thickening of the parts remedial means should be applied, directed by
a skilful physician. The nostrums for the cure of deafness are
generally of an oleaginous character, and may be beneficial in cases
of defective hearing caused by an accumulation of wax upon the drum of
the ear, but in this respect they are no better than the ordinary
animal oils.

  -=-=-=-=-=-=-=-=-=-=-=-=

What is the remedy where there is an accumulation of wax? 977. What is
the effect on hearing if the Eustachian tube is obstructed? 978. What
is the treatment when deafness is caused by inflammation or ulceration
the fauces? What is said of the nostrums used for deafness?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XLVIII

MEANS OF PRESERVING THE HEALTH.[23]

  [23] It is advised, that a thorough review of the hygiene of the
       preceding chapters be given from the suggestions contained in
       this.


979. Our bodies are constituted in harmony with certain laws, and
every person should learn these, in order to regulate his actions and
the performance of his duties, so that health may be unimpaired, and
the power of enjoyment, activity, and usefulness continue while life
lasts.

980. It is a law of the bones and the muscles, that they should either
be used in some vocation, or called into action by some social play
and active sport.

981. All admit that food is necessary to sustain life; and unless it
be of a proper quality, taken in proper quantities, and at proper
times, the functions of the digestive organs will be deranged, and
disease produced.

982. Pure air is essential to the full enjoyment of health. The impure
air of unventilated rooms may be breathed, and the effect be so
gradual as not to arrest attention; yet it is a violation of the
physical laws, and, sooner or later, we pay the penalty in disease and
suffering.

  -=-=-=-=-=-=-=-=-=-=-=-=

979. Why is it incumbent on every person to learn the laws of health?
980. Give a law of the muscles. 981. In preserving the health, is it
necessary to give attention to the food which is eaten? Why? 982. What
beside food is essential to the full enjoyment of health? What is said
of the impure air of unventilated rooms? 983. What should be observed
in regard to sleep?

  -=-=-=-=-=-=-=-=-=-=-=-=

983. The body also requires sleep; and if it is not taken at the right
time, or with regularity, we do not feel full refreshment from "tired
nature's sweet restorer." Let youth be taught that "early to bed and
early to rise" gives him health and its attendant blessings. The
brain, like other organs of the body, should be called into action at
proper times.

984. From the extent of the surface of the skin, and the close
sympathy that exists between it and those organs whose office is, to
remove the waste particles of matter from the body, it therefore
becomes very important in the preservation of the health, that the
functions of this membrane be properly maintained.

985. The function of the circulatory and secretory organs, together
with the operations of absorption and nutrition, should be steadily
maintained, as vitality and the generation of animal heat are
intimately connected with these processes. In the proper performance
of these functions, very much depends on the observance of the laws
of the muscular, digestive respiratory, dermoid, and nervous
apparatuses.


REMOVAL OF DISEASE.

986. It is seldom that a physician is called in the first stages of
disease. At this important period, the treatment adopted should be
proper and judicious, or the sufferings of the patient are increased,
and life, to a greater or less degree, is jeopardized. Hence the
utility of knowing what _should be done_, and what _should not be
done_, in order that the health may be rapidly regained.

987. In all instances of acute disease, it is proper to rest, not only
the body, but the mind. To effect this, the patient should cease from
physical exertion, and also withdraw his thoughts from study and
business operations. This should be done, even if the person is but
slightly indisposed.

  -=-=-=-=-=-=-=-=-=-=-=-=

984. Why should the functions of the skin be properly maintained? 985.
Show the necessity of maintaining properly other functions of the
system. 986. What is important in the first stages of disease? 987.
What is proper in all instances of acute disease? How can it be
effected?

  -=-=-=-=-=-=-=-=-=-=-=-=

988. Select a room for a sick person that is exposed to as little
external noise as possible, as impressions made on the organ of
hearing greatly influence the nervous system. Likewise select a
spacious, well-ventilated apartment, that has no superfluous
furniture. The practice of placing a sick person in a small,
ill-arranged sleeping-room, when a more spacious room can be used, is
poor economy, not to say unkind.

989. Care is necessary in regulating the light of a sick-room. While a
strong light would produce an increased action of the vessels of the
brain, a moderate light would be an appropriate stimulus to this
organ. It is seldom or never necessary to exclude all light from the
sick-chamber.

990. A sick person, whether a child or an adult, should not be
disturbed by visitors, even if their calls are short. The excitement
of meeting them is followed by a depression of the nervous system. The
more dangerous and apparently nearer death the sick person is, the
more rigorous should be the observance of this suggestion. Nor should
the sick-room be opened to privileged classes; for the excitement
caused by a visit from relations and the virtuous, will do as much
injury to the sick, as that produced by strangers and the vicious.

991. The custom of visiting and conversing with sick friends during
the intervals of daily labor, and particularly on _Sunday_, is a great
evil. No person will thus intrude herself in the sick-chamber who
cares more for the welfare of the suffering friend than for the
gratification of a _sympathetic curiosity_. Inquiries can be made of
the family respecting the sick, and complimentary or necessary
messages can be communicated through the nurse.

  -=-=-=-=-=-=-=-=-=-=-=-=

988. What rooms should be selected for the sick? Why? 989. What is
said in reference to the quantity of light admitted into a sick-room?
990. What effect have calls on the sick? 991. What is said of the
custom of calling and conversing with the sick during the intervals of
daily labor?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Illustration._ While attending a Miss B., of N. H., sick of fever, I
pronounced her better, withdrew medicine, directed a simple, low diet,
and the exclusion of all visitors. In the evening I was sent for to
attend her. There was a violent relapse into the disease, which
continued to increase in severity until the fourth day, when death
terminated her sufferings. I learned that, soon after I gave
directions that no visitors be admitted into her room, several
_particular_ friends were permitted to enter the chamber and talk with
the sick girl. Their conversation produced a severe headache; and, to
use the language of the patient, "it seemed as if their talk would
kill me;" and _it did kill her_.

992. No _solid food_ should be taken in the first stages of disease,
even if the affection is slight. The thirst can be allayed by drinking
cold water, barley-water, and other preparations of an unstimulating
character. It is wrong to tempt the appetite of a person who is
indisposed. The cessation of a desire for food, is the warning of
nature, that the system is in such a state that it cannot be
digested.

993. When a patient is recovering from illness, the food should be
simple, and in quantities not so great as to oppress the stomach. It
should also be given with regularity. "Eat little and often," with no
regard to regularity, is a pernicious practice.

994. When a physician attends a sick person, he should have the
_special_ management of the food, particularly after the medicine has
been withdrawn and the patient is convalescent. The prevailing idea
that _every_ person may safely advise relative to food, or that the
appetite of the convalescing person is a competent guide, is
dangerous; and cannot be too much censured.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give an illustration. 992. What suggestion relative to food in the
first stages of disease? How can the thirst be allayed? 993. When the
patient is convalescent, how should the food be given? What is said of
the practice of eating "little and often"? 994. Who should have the
special management of food when medicine is withdrawn? What idea
prevails in the community?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Illustration._ In 1832, I attended a Miss M., sick of fever. After an
illness of a few days, the fever abated, and I directed a simple,
unstimulating diet. Business called me from the town two days. During
my absence, a sympathizing, officious matron called; found her weak,
but improving; and told her she needed food to strengthen her; and
that "it would now do her good." Accordingly, eggs and a piece of
beefsteak were prepared, and given to the convalescent girl. She ate
heartily, and the result was a relapse into a fever more violent than
the first attack.

995. It is very important in disease that _the skin be kept clean_. A
free action of the vessels of this part of the body exerts a great
influence in removing disease from the internal organs, as well as
keeping them in health. If the twenty or thirty ounces of waste,
hurtful matter, that passes through the "pores" of the skin in
twenty-four hours, are not removed by frequent bathing and dry
rubbing, it deranges the action of the vessels that separate this
waste matter from the blood, and thus increases the disease of the
internal organs.

_Illustration._ Mrs. M. R., of N., Mass., was afflicted with disease
of the lungs and cough. This was accompanied with a dry, inactive
condition of the skin. As medicine had no salutary effect in relieving
her cough, she was induced by the advice of the clergyman of the
parish to enter upon a systematic course of bathing twice every day.
Soon the skin became soft, its proper functions were restored, the
disease of the lungs yielded, and the cough disappeared.

996. Every sick person should breathe _pure air_. The purer the blood
that courses through the body, the greater the energy of the system
to remove disease. The confined vitiated air of the sick-chamber, not
unfrequently prolongs disease; and in many instances, the affection is
not only aggravated, but, even rendered fatal, by its injurious
influences.

  -=-=-=-=-=-=-=-=-=-=-=-=

Give an illustration of the evil effects attending such an idea. 995.
Does the skin exert a great influence in removing disease from the
internal organs, as well as in keeping them in health? Give an
illustration 996. Why should every sick person, particularly, breathe
pure air?

  -=-=-=-=-=-=-=-=-=-=-=-=

_Illustrations._ 1st. In 1833, I was called, in consultation with
another physician, to Mr. H., who was much debilitated, and delirious.
For several successive days he had not slept. His room was kept very
warm and close, for fear he would "take cold." The only change that I
made in the treatment, was to open the door and window, at a distance
from the bed. In a short time, the delirium ceased, and he fell into a
quiet slumber. From this time he rapidly recovered, and the delirium
was probably the result of breathing impure air.

2d. Formerly, every precaution was used to prevent persons sick of the
small-pox from breathing fresh air. When Mrs. Ramsay had this disease
in Charleston, S.C., her friends, supposing that life was extinct,
caused her body to be removed from the house to an open shed. The pure
air revived the vital spark. The result probably would have been
different, had she been kept a few hours longer in the vitiated air.

997. The influence of habit should not be disregarded in the removal
of disease. If food or drink is to be administered, however small in
quantity or simple its quality, it should be given at or about the
time when the ordinary meals were taken in health.

998. Again, the usual time when the patient was in the habit of
retiring for sleep should be observed, and all preparation necessary
for the sick-room during the night should be made previous to this
hour. Efforts should also be made to evacuate the waste matter of the
digestive and urinary organs at the period which habit has formed in
health. This is not only a remedial agent in disease, but often
precludes the necessity of laxative or drastic cathartics.

  -=-=-=-=-=-=-=-=-=-=-=-=

Are not diseases prolonged, and even rendered fatal, from breathing
the impure, vitiated air of the sick-chamber? Give illustration 1st.
Give illustration 2d. 997. What is said respecting the influence of
habit in removing disease?

  -=-=-=-=-=-=-=-=-=-=-=-=

999. MEDICINE is sometimes necessary to _assist_ the natural powers of
the system to remove disease; but it is only an _assistant_. While
emetics are occasionally useful in removing food and other articles
from the stomach that would cause disease if suffered to remain, and
cathartics are valuable, in some instances, to relieve the alimentary
canal of irritating residuum, yet the frequent administration of
either will cause serious disease.

1000. Although medicine is useful in some instances, yet, in a great
proportion of the cases of disease, including fevers and inflammations
of all kinds, attention to the laws of health will tend to relieve the
system from disease; more certainly and speedily, and with less
danger, than when medicines are administered.

1001. Thomas Jefferson, in writing to Dr. Wistar, of Philadelphia,
said, "I would have the physician learn the limit of his art." I would
say, Have the matrons, and those who are continually advising "herb
teas," and other "cure-alls," for any complaint, labelled with some
popular name, learn the limits of their duty, namely, attention to the
laws of health. The rule of every family, and each individual, should
be, to touch not, taste not of medicine of _any kind_, except when
directed by a well-educated and honest physician, (sudden disease from
accidents excepted.)

  -=-=-=-=-=-=-=-=-=-=-=-=

999. What is said of the use of medicine? 1000. Of its use in fevers
and many other cases of disease? 1001. What remark by Thomas Jefferson
to Dr. Wistar? What should matrons learn? What should be the rule of
every person in regard to taking medicine? What exception?

  -=-=-=-=-=-=-=-=-=-=-=-=



CHAPTER XLIX.

DIRECTIONS FOR NURSES.


1002. The nurse requires knowledge and practice to enable her to
discharge aright her duty to the patient, as much as the physician and
surgeon do to perform what is incumbent on them. Woman, from her
constitution and habits, is the natural nurse of the sick; and, in
general, no small portion of her time is spent in ministering at the
couch of disease and suffering.

1003. As the young and vigorous, as well as the aged and the infirm,
are liable to be laid upon the bed of sickness, by an epidemic, or
imprudent exposure, or by some accident, it is therefore necessary
that the girl, as well as the matron, may know how she can render
services in an efficient and proper manner. No _girl_ should consider
her education complete who is not acquainted with the principles of
the duties of a general nurse and a temporary watcher.

1004. It is to be regretted, that while we have medical schools and
colleges to educate physicians, there is no institution to educate
_nurses_ in their equally responsible station. In the absence of such
institutions, the defect can be remedied, to some extent, by teaching
every girl _hygiene_, or _the laws of health_. To make such knowledge
more available and complete, attention is invited to the following
suggestions relative to the practical duties of a nurse.

  -=-=-=-=-=-=-=-=-=-=-=-=

1002. Does the nurse require knowledge and practice in her employment,
as well as the physician? Who is the natural nurse of the sick? 1003.
What, then, is incumbent on every girl? 1004. Should there be schools
to educate nurses, as well as physicians and surgeons?

  -=-=-=-=-=-=-=-=-=-=-=-=

1005. BATHING. The nurse, before commencing to bathe the patient,
should provide herself with water, two towels, a sponge, a piece of
soft flannel, and a sheet. The temperature of the room should also be
observed.

1006. When the patient is feeble, use _tepid_ or warm water. Cold
water should only be used when the system has vigor enough to produce
reaction upon the skin. This is shown by the increased redness of the
skin, and a feeling of warmth and comfort, after a proper amount of
friction. Before using the sponge to bathe, a sheet, or fold of cloth,
should be spread smoothly over the bed, and under the patient, to
prevent the bed-linen on which the patient lies from becoming damp or
wet.

1007. Apply the wet sponge to one part of the body at a time; as the
arm, for instance. By doing so, the liability of contracting chills is
diminished. Take a dry, soft towel, wipe the bathed part, and follow
this by vigorous rubbing with a crash towel, or, what is better, a
mitten made of this material; then use briskly a piece of soft
flannel, to remove all moisture that may exist on the skin, and
particularly between the fingers and the flections of the joints. In
this manner bathe the entire body.

1008. The sick should be thoroughly bathed, at least twice in
twenty-four hours. Particular attention should be given to the parts
between the fingers and toes, and about the flections of the joints,
as the accumulation of the excretions is most abundant on these parts.
In bathing, these portions of the system are very generally neglected.
The best time for bathing, is when the patient feels most vigorous,
and freest from exhaustion. The practice of daubing the face and hands
with a towel dipped in hot rum, camphor, and vinegar, does not remove
the impurities, but causes the skin soon to feel dry, hard, and
uncomfortable.

  -=-=-=-=-=-=-=-=-=-=-=-=

1005. What should a nurse provide herself with, before bathing a
patient? 1006. When should cold water be used? 1007. How should the
bathing then be performed, so that the patient may not contract a
cold? 1008. How often should a sick person be bathed? What is said of
daubing the face and hands merely with a wet cloth?

  -=-=-=-=-=-=-=-=-=-=-=-=

1009. FOOD. It is the duty of every woman to know how to make the
simple preparations adapted to a low diet, in the most wholesome and
the most palatable way. Water-gruel,[24] which is the simplest of all
preparations, is frequently so ill-made as to cause the patient to
loathe it. Always prepare the food for the sick, in the neatest and
most careful manner.

  [24] Directions for making the simple preparations for the sick are
       found in almost every cook-book.

1010. When the physician enjoins abstinence from food, the nurse
should strictly obey the injunction. She should be as particular to
know the physician's directions about diet, as in knowing how and when
to give the prescribed medicines, and obey them as implicitly.

1011. When a patient is convalescent, the desire for food is generally
strong, and it often requires firmness and patience, together with
great care, on the part of the nurse, that the food is prepared
suitably, and given at proper times The physician should direct how
frequently it should be taken.

1012. PURE AIR. It is the duty of the nurse to see that not only the
room is well ventilated in the morning, but that fresh air is
constantly admitted during the day. Great care must be taken, however,
that the patient does not feel the current.

1013. Bed-linen, as well as that of the body, should be aired every
day, and oftener changed in sickness than in health. All clothing,
when changed, should be well dried, and warmed by a fire previous to
its being put on the patient or the bed.

  -=-=-=-=-=-=-=-=-=-=-=-=

1009. Should every woman know how to make the simple preparations
adapted to a low diet? 1010. Should the nurse strictly obey the
injunctions of the physician relative to food? 1011. What period of a
person's illness requires the most care in regard to the food? 1012.
Give another duty of the nurse. 1013. What directions respecting the
bed-linen of the patient? What is necessary when there is a change of
clothing?

  -=-=-=-=-=-=-=-=-=-=-=-=

1014. TEMPERATURE. The warmth of the chamber should be carefully
watched by the nurse. The feelings of the patient or nurse are not to
be relied on as an index of the temperature of the room. There should
be a well-adjusted thermometer in every sick-room. This should be
frequently consulted by the nurse.

1015. The temperature of the sick-chamber should be _moderate_. If it
is so cold as to cause a chill, the disease will be aggravated. If, on
the other hand, it is too warm, the patient is enfeebled and rendered
more susceptible to cold on leaving the sick-chamber. The Latin maxim,
"_In medio tutissimus ibis_," (in medium there is most safety,) should
be regarded in the rooms of the sick.

1016. QUIET. The room of the patient should be kept free from noise.
The community should be guided by this rule, that no more persons
remain in the room of the sick, than the welfare of the patient
demands. It is the duty of the physician to direct when visitors can
be admitted or excluded from the sick-room, and the nurse should see
that these directions are enforced.

1017. The movements of the attendants should be gentle and noiseless.
Shutting doors violently, creaking hinges, and all unnecessary noise,
should be avoided. Most persons refrain from loud talking in the sick
chamber, but are not equally careful to abstain from _whispering_,
which is often more trying than a common tone.

1018. It is the duty of the nurse to ascertain the habits of the
patient as respects the period for eating and sleep, when in health,
that she may prepare the food and arrange the sick-room in accordance
with the practice of the patient. If the person who is sick is
ignorant of the necessity of the removal of the waste products from
the system the nurse should invite attention to these functions at
such periods as are in accordance with the previous habits of the
patient.

  -=-=-=-=-=-=-=-=-=-=-=-=

1014. Why should there be a well-adjusted thermometer in every
sick-chamber? 1015. What is said of the temperature of the sick-chamber?
1016. Why should the sick-room be kept quiet? 1017. What is said of noise
in the sick-chamber? Of whispering? 1018. Should the habits of the
patient be regarded in reference to the period for eating and sleep?

  -=-=-=-=-=-=-=-=-=-=-=-=

1019. The deportment and remarks of the nurse to the patient should be
tranquil and encouraging. The illness of a friend, or persons who have
recently died, should not be alluded to in the sick-room. No doubts or
fears of the patient's recovery, either by a look or by a word, should
be communicated by the nurse in the chamber of the sick. When such
information is necessary to be communicated, it is the duty of the
physician to impart it to the sick person.

1020. The nurse should not confine herself to the sick-room more than
six hours at a time. She should eat her food regularly, sleep at
regular periods, and take exercise daily in the open air. To do this,
let her quietly leave the room when the patient is sleeping. A
watcher, or temporary nurse, may supply her place. There is but little
danger of contracting disease, if the nurse attends to the simple laws
of health, and remains not more than six hours at a time in the
sick-room.


DIRECTIONS FOR WATCHERS.

1021. These necessary assistants, like the nurse, should have
knowledge and practice. They should ever be cheerful, kind, firm, and
attentive in the presence of the patient.

1022. A simple, nutritious supper should be eaten before entering the
sick-room; and it is well, during the night, to take some plain food.

  -=-=-=-=-=-=-=-=-=-=-=-=

1019. What should be the deportment of the nurse toward the patient?
Should doubts and fears of the patient's recovery be communicated in
the sick-room? When necessary to impart such intelligence, on whom
does it depend? 1020. How long should a nurse remain in the
sick-chamber at a time? 1021. What qualifications are necessary in a
watcher? 1022. What directions in regard to the food of the watcher?

  -=-=-=-=-=-=-=-=-=-=-=-=

1023. When watching in cold weather, a person should be warmly
dressed, and furnished with an extra garment, as a cloak or shawl,
because the system becomes exhausted toward morning, and less heat is
generated in the body.

1024. Light-colored clothing should be worn by those who have care of
the sick, in preference to dark-colored apparel; particularly if the
disease is of a contagious character. Experiments have shown, that
black and other dark colors will absorb more readily the subtile
effluvia that emanate from sick persons, than white or light colors.

1025. Whatever may be wanted during the night, should be brought into
the sick-chamber, or the adjoining room, before the family retires for
sleep, in order that the slumbers of the patient be not disturbed by
haste, or searching for needed articles.

1026. The same general directions should be observed by watchers, as
are given to the nurse; nor should the watcher deem it necessary to
make herself acceptable to the patient by exhausting conversation.

1027. It can hardly be expected that the farmer, who has been laboring
hard in the field, or the mechanic, who has toiled during the day, is
qualified to render all those little attentions that a sick person
requires. Hence, would it not be more benevolent and economical to
employ and _pay_ watchers, who are qualified by knowledge and
_training_, to perform this duty in a faithful manner, while the
kindness and sympathy of friends may be _practically_ manifested by
assisting to defray the expenses of these qualified and useful
assistants?

  -=-=-=-=-=-=-=-=-=-=-=-=

1023. When watching in cold weather, what precaution is necessary?
1024. What is said relative to the color of the clothing worn in the
sick-room? 1025. What suggestions to watchers relative to the
arrangement of the sick-chamber? 1026. What should watchers observe?
1027. What is said of employing those persons to watch who labor hard
during the day?

  -=-=-=-=-=-=-=-=-=-=-=-=



APPENDIX.


POISONS AND THEIR ANTIDOTES

1028. POISONING, either from accident or design, is of such frequency
and danger, that it is of the greatest importance that every person
should know the proper mode of procedure in such cases, in order to
render immediate assistance when within his power.

1029. Poisons are divided into two classes--_mineral_ (which include
the acids) and _vegetable_.

1030. The first thing, usually, to be done, when it is ascertained
that a poison has been swallowed, is to evacuate the stomach, unless
vomiting takes place spontaneously. Emetics of the sulphate of zinc,
(white vitriol,) or ipecacuanha, (ipecac,) or ground mustard seed,
should be given.

1031. When vomiting has commenced, it should be aided by large and
frequent draughts of the following drinks: flaxseed tea, gum-water,
slippery-elm tea, barley water, sugar and water, or any thing of a
mucilaginous or diluent character.


MINERAL POISONS.

1032. AMMONIA.--The _water of ammonia_, if taken in an over-dose, and
in an undiluted state, acts as a violent corrosive poison.

1033. The best and most effectual antidote is _vinegar_. It should be
administered in water, without delay. It neutralizes the ammonia, and
renders it inactive. Emetics should not be given.


1034. ANTIMONY.--The _wine of antimony_ and _tartar emetic_, if taken
in over-doses, cause distressing vomiting. In addition to the diluent,
mucilaginous drinks, give a tea-spoonful of the sirup of poppies,
paregoric, or twenty drops of laudanum, every twenty minutes, until
five or six doses have been taken, or the vomiting ceases.

  -=-=-=-=-=-=-=-=-=-=-=-=

1025. Is it useful to know the antidotes or remedies for poison? 1029.
Into how many classes are poisons divided? 1030. What is the first
thing to be done when it is ascertained that poison has been
swallowed? 1031. What should be taken after the vomiting has
commenced? 1032. What effect has an over-dose of ammonia? 1033. The
antidote? Should an emetic be given for this poison? 1034. What effect
has an over-dose of the wine of antimony or tartar emetic?

  -=-=-=-=-=-=-=-=-=-=-=-=

1035. The antidotes are _nutgalls_ and _oak bark_, which may be
administered in infusion, or by steeping in water.


1036. ARSENIC.--When this has been taken, administer an emetic of
ipecac, speedily, in mucilaginous teas, and use the stomach-pump as
soon as possible.

1037. The antidote is the _hydrated peroxide of iron_. It should be
kept constantly on hand at the apothecaries' shops. It may be given in
any quantity, without injurious results.


1038. COPPER.--The most common cause of poisoning from this metal, is
through the careless use of cooking utensils made of it, on which the
_acetate of copper_ (verdigris) has been allowed to form. When this
has been taken, immediately induce vomiting, give mucilaginous drinks,
or the _white of eggs_, diffused in water.

1039. The antidote is the _carbonate of soda_, which should be
administered without delay.


1040. LEAD.--The _acetate_ (sugar) _of lead_ is the preparation of
this metal, which is liable to be taken accidentally, in poisonous
doses. Induce immediate vomiting, by emetics of ground mustard seed,
sulphate of zinc, and diluent drinks.

1041. The antidote is diluted _sulphuric acid_. When this acid is not
to be obtained, either the sulphate of magnesia, (epsom salts,) or the
sulphate of soda, (glauber's salts,) will answer every purpose.


1042. MERCURY.--The preparation of this mineral by which poisoning is
commonly produced, is _corrosive sublimate_. The mode of treatment to
be pursued when this poison has been swallowed, is as follows: The
_whites of a dozen eggs_ should be beaten in two quarts of cold water,
and a tumbler-full given every two minutes, to induce vomiting. When
the whites of eggs are not to be obtained, soap and water should be
mixed with wheat flour, and given in copious draughts, and the
stomach-pump introduced as soon as possible. Emetics or irritating
substances should not be given.


1043. NITRE--_Saltpetre._--This, in over-doses, produces violent
poisonous symptoms. Vomiting should be immediately induced by large
doses of mucilaginous, diluent drinks; but emetics which irritate the
stomach should not be given.

  -=-=-=-=-=-=-=-=-=-=-=-=

1035. What is the antidote? 1036. What should immediately be done when
arsenic is swallowed? 1037. What is the antidote? Can any quantity of
this preparation of iron be given without injurious results? 1038.
What should be given when verdigris has been taken into the stomach?
1039. What is the antidote? 1040. What should immediately be given
when sugar of lead is taken? 1041. What is the antidote? 1042. Give
the treatment when corrosive sublimate has been swallowed. 1043. What
effect has an over-dose of saltpetre? What treatment should be
adopted?

  -=-=-=-=-=-=-=-=-=-=-=-=


1044. ZINC.--Poisoning is sometimes caused by the _sulphate of zinc_,
(white vitriol.) When this takes place, vomiting should be induced,
and aided by large draughts of mucilaginous and diluent drinks. Use
the stomach-pump as soon as possible.

1045. The antidote is the _carbonate_, or _super-carbonate of soda_.


1046. NITRIC, (aqua fortis,) MURIATIC, (MARINE ACID,) OR SULPHURIC
(OIL OF VITRIOL,) ACIDS, may be taken by accident, and produce
poisonous effects.

1047. The antidote is _calcined magnesia_, which should be freely
administered, to neutralize the acid and induce vomiting. When
magnesia cannot be obtained, the _carbonate of potash_ (salæratus) may
be given. _Chalk_, powdered and given in solution, or strong _soap
suds_, will answer a good purpose, when the other articles are not at
hand. It is of very great importance that something be given speedily,
to neutralize the acid. One of the substances before mentioned should
be taken freely, in diluent and mucilaginous drinks, as gum-water,
milk, flaxseed, or slippery-elm tea. Emetics ought to be avoided.


1048. OXALIC ACID.--This acid resembles the sulphate of magnesia,
(epsom salts,) which renders it liable to be taken, by mistake, in
poisonous doses. Many accidents have occurred from this circumstance.
They can easily be distinguished by tasting a small quantity. _Epsom
salts_, when applied to the tongue, have a very bitter taste, while
_oxalic acid_ is intensely sour.

1049. The antidote is _magnesia_, between which and the acid a
chemical action takes place, producing the oxalate of magnesia, which
is inert. When magnesia is not at hand, _chalk_, _lime_, or _carbonate
of potash_, (salæratus,) will answer as a substitute. Give the
antidote in some of the mucilaginous drinks before mentioned. No time
should be lost in introducing the stomach-pump as soon as a surgeon
can be obtained.


1050. LEY.--The ley obtained by the leaching of ashes may be taken by
a child accidentally. The antidote is vinegar, or oil of any kind. The
vinegar neutralizes the alkali by uniting with it, forming the acetate
of potash. The oil unites with the alkali, and forms soap, which is
less caustic than the ley. Give, at the same time, large draughts of
mucilaginous drinks, as flaxseed tea, &c.

  -=-=-=-=-=-=-=-=-=-=-=-=

1044. What is the antidote for white vitriol? 1047. What is the
antidote for aqua fortis and oil of vitriol? Should emetics be
avoided? 1048. How can oxalic acid be distinguished from epsom salts?
1049. What is the antidote for an over-dose of oxalic acid? When
magnesia cannot be obtained, what will answer as a substitute? 1050.
What is the antidote when ley is swallowed?

  -=-=-=-=-=-=-=-=-=-=-=-=


VEGETABLE POISONS.

1051. The vegetable poisons are quite as numerous, and many of them
equally as virulent, as any in the mineral kingdom. We shall describe
the most common, and which, therefore, are most liable to be taken.


1052. OPIUM.--This is the article most frequently resorted to by those
wishing to commit suicide, and, being used as a common medicine, is
easily obtained. From this cause, also, mistakes are very liable to be
made, and accidents result from it. Two of its preparations,
_laudanum_ and _paregoric_, are frequently mistaken for each other;
the former being given when the latter is intended.

1053. _Morphia_, in solution, or _morphine_, as it is more commonly
called by the public, is a preparation of the drug under consideration,
with which many cases of poisoning are produced. It is the active
narcotic principle of the opium; and one grain is equal to six of this
drug in its usual form.

1054. When an over-dose of opium, or any of its preparations, has been
swallowed, the stomach should be evacuated as speedily as possible. To
effect this, a teaspoonful of ground mustard seed, or as much tartar
emetic as can be held on a five cent piece, or as much _ipecacuanha_
as can be held on a twenty-five cent piece, should be mixed in a
tumbler of warm water, and one half given at once, and the remainder
in twenty minutes, if the first has not, in the mean time, operated.
In the interval, copious draughts of warm water, or warm sugar and
water, should be drank.

1055. The use of the stomach-pump, in these cases, is of the greatest
importance, and should be resorted to without delay. After most of the
poison has been evacuated from the stomach, a strong infusion of
_coffee_ ought to be given; or some one of the vegetable acids, such
as _vinegar_, or _lemon-juice_, should be administered.

1056. The patient should be kept in motion, and salutary effects will
often be produced by dashing a bucket of cold water on the head.
_Artificial respiration_ ought to be established, and kept up for some
time. If the extremities are cold, apply warmth and friction to them.
After the poison has been evacuated from the stomach, stimulants, as
warm wine and water, or warm brandy and water, should be given, to
keep up and sustain vital action.


1057. STRAMONIUM--_Thorn-Apple._--This is one of the most active
narcotic poisons, and, when taken in over-doses, has, in numerous
instances, caused death.

  -=-=-=-=-=-=-=-=-=-=-=-=

1051. Are vegetable poisons as numerous and as virulent in their
effects as mineral? 1052. What is said of opium and its preparations?
1054, 1055, 1056. What treatment should be adopted when an over-dose
of opium or any of its preparations is taken? 1057. What is said of
stramonium?

  -=-=-=-=-=-=-=-=-=-=-=-=

1058. HYOSCIAMUS--_Henbane._--This article, which is used as a
medicine, if taken in improper doses, acts as a virulent irritating
and narcotic poison.

1059. The treatment for the two above-mentioned articles is similar to
that of poisoning from over-doses of opium.


1060. CONIUM--_Hemlock._--Hemlock, improperly called, by many,
_cicuta_, when taken in an over-dose, acts as a narcotic poison. It
was by this narcotic that the Athenians used to destroy the lives of
individuals condemned to death by their laws. Socrates is said to have
been put to death by this poison. When swallowed in over-doses, the
treatment is similar to that of opium, stramonium, and henbane, when
over-doses are taken.


1061. BELLADONNA--_Deadly Nightshade._--CAMPHOR. ACONITE--_Monkshood_,
_Wolfsbane._ BRYONIA--_Bryony._ DIGITALIS--_Foxglove._
DULCAMARA--_Bittersweet._ GAMBOGE. LOBELIA--_Indian Tobacco._
SANGUINARIA--_Bloodroot._ OIL OF SAVIN. SPIGELIA--_Pinkroot._
STRYCHNINE--_Nux vomica._ TOBACCO.--All of these, when taken in
over-doses, are poisons of greater or less activity. The treatment of
poisoning, by the use of any of these articles, is similar to that
pursued in over-doses of opium. (See OPIUM, page 442.)


1062. In _all_ cases of poisoning, call a physician as soon as
possible.

  -=-=-=-=-=-=-=-=-=-=-=-=

1058. Of henbane? 1059. What should be the treatment when an
over-dose of stramonium or henbane is taken? 1060. What name is
sometimes improperly given to _conium_, or hemlock? How was this
narcotic poison used by the Athenians? How are the effects of an
over-dose counteracted? 1061. What is the treatment when an
over-dose of deadly nightshade, monkshood, foxglove, bittersweet,
gamboge, lobelia, bloodroot, tobacco, &c., is taken? 1062. Should a
physician be called in all cases when poison is swallowed?

  -=-=-=-=-=-=-=-=-=-=-=-=


A.

The essential parts of every secretory apparatus are a simple
membrane, apparently textureless, named the _primary_, or _basement
membrane_, certain cells and blood-vessels. The serous and mucous
membrane are examples.


B.

The division and description of the different membranes and tissues
are not well defined and settled by anatomical writers. This is not a
material defect, as a clear description of the different parts of the
system can be given by adopting the arrangement of almost any writer.


C.

FAT is one of the non-nitrogenous substances. It forms the essential
part of the adipose tissue. Chemical analysis shows that all fatty
substances are compounds of carbon, hydrogen, and oxygen. They are
lighter than water, generally fluid at the natural temperature of the
body, and burn with a bright flame, forming water and carbonic acid.

CASEINE is abundantly found in milk. When dried, it constitutes
cheese. Alcohol, acids, and the stomach of any of the mammalia
coagulate it; and it is also soluble in water. It is found in the
blood, bile, saliva, and the lens of the eye.

CHONDRINE is a variety of gelatin. It is obtained from cartilage. It
is soluble in warm water, but solidifies on cooling.

LACTIC ACID is common to all the solids and fluids of the system. It
is found united with potash, soda, lime, or magnesia.


D.

The word _duodenum_ is derived from the Latin, signifying "twelve,"
since the intestine, of which this is the name, is usually about
twelve fingers' breadth in length. The _jejunum_ is also from the
Latin _jejunum_, empty, since it is usually found in that condition
after death, as the food seems to pass rapidly through this part of
the intestine. The term _ileum_ is from the Greek, signifying "to
twist," since it always appears in a contorted condition. The name
_cæcum_ is derived from the fact of its being a blind or short sack,
perforated by the extremity of the ileum. The name of the next
division of the intestine--_colon_--is from the Greek, "to prohibit,"
as the contents of the alimentary canal pass slowly through this
portion. The _rectum_ is named from the straight direction that it
assumes in the latter part of its course.


E.

The food is forced through the alimentary canal by contractions of its
muscular coat, produced by the nervous filaments of the sympathetic
system, not being at all dependent on the cerebro-spinal centre. This
is called the peristaltic, or vermicular motion. The great length of
intestine in all animals, and especially in the herbivorous ones, is
owing to the necessity of exposing the food to a large number of the
lacteals, that the nourishment may all be taken from it.


F.

The different processes through which the food passes before
assimilation are of considerable interest. The mastication and mixture
of the saliva with the food are purely of a mechanical nature. When
any solid or fluid substance is placed upon the tongue, or in contact
with the inner surface of the cheeks, by an involuntary act, the
salivary glands are stimulated to activity, and commence pouring the
saliva into the mouth through the salivary ducts. As soon as
mastication commences, the contraction of the masseter and other
muscles employed in mastication stimulates the salivary glands to
increased action, and a still greater quantity of saliva is secreted
and forced upon the food, which is constantly being ground to a finer
condition, until it is sufficiently reduced for deglutition.

Whether the salivary fluid acts any other part than simply that of a
demulcent to assist the gastric juice in still further dissolving the
food, is yet a matter of some doubt, although it is found that no
other liquid will equally well subserve the process of digestion and
promote health.

After the food is in the condition ready to be swallowed, by an
apparently involuntary motion, it is placed upon the back of the
tongue, which carries it backwards to the top of the pharynx, where
the constrictions of the pharynx, aided by the muscles of the tongue
and floor of the mouth, with a sudden and violent movement thrust it
beyond the epiglottis, in order to allow the least necessary time to
the closure of the glottis, after which, by the compression of the
oesophagus, it is forced into the stomach.

Here it is that the true business of digestion commences. For as soon
as any substance except water enters the stomach, this organ, with
involuntary movements, that seem almost like instinct, commences the
secretion of the gastric juice, and by long-continued contractions of
its muscular coat, succeeds in effecting a most perfect mixture of the
food with this juice, by which the contents of the stomach are reduced
to the softest pulp.

The gastric juice, in its pure state, is a colorless, transparent
fluid; "inodorous, a little saltish, and perceptibly acid. It
possesses the property of coagulating albumen, and separating the whey
of milk from its curd, and afterwards completely dissolving the curd.
Its taste, when applied to the tongue, is similar to that of
mucilaginous water, slightly acidulated with muriatic acid." The
organs of its secretion are an immense number of tubes or glands, of a
diameter varying from one five hundredth to one three hundredth of an
inch, situated in the mucous coat of the stomach, and receiving their
blood from the gastric arteries. A chemical analysis shows it to
consist of water, mucilage, and the several free acids--muriatic,
acetic, lactic, and butyric, together with a peculiar organic matter
called _pepsin_, which acts after the manner of ferments between the
temperature of 50° and 104° F.

The true process of digestion is probably owing to the action of
pepsin and the acids, especially if the presence of the chloro-hydric
or muriatic be admitted; since we know, by experiments out of the
body, that chlorine, one of its elements, is a powerful solvent of all
organic substances.

The antiseptic properties of the gastric juice, as discovered by
experiments made on Alexis St. Martin, doubtless have much influence
on digestion, although their true uses are probably not yet known.

As soon as the food is reduced to a state of fluidity, the pyloric
orifice of the stomach is unclosed, and it is thrust onwards through
the alimentary canal, receiving in the duodenum the secretions of the
liver and pancreas, after which it yields to the lacteals its nutrient
portion, and the residuum is expelled from the body.

There have been many hypotheses in regard to the nature of the
digestive process. Some have supposed that digestion is a mere
mechanical process, produced by the motion of the walls of the
stomach; while others, in later times, have considered it as under the
influence of a spirit separate from the individual, who took up his
residence in the stomach and regulated the whole affair; while others
still would make it out to be a chemical operation, and thus
constitute the stomach a sort of laboratory. But to all these
ridiculous hypotheses Sir John Hunter has applied the following
playful language: "Some will have it that the stomach is a mill;
others that it is a fermenting vat; and others that it is a stewpan;
but in my view of the matter, it is neither a mill, a fermenting vat,
nor a stewpan, but a stomach, _a stomach_!"

At the present day this process is regarded as a complex, and not a
simple operation. It seems to be a process in which the mechanical,
chemical, and vital agencies must all act in harmony and order; for if
one of these be withdrawn, the function cannot be sustained for any
considerable length of time; and of the chemical and mechanical parts
of the process, since the former is much more important, and, as a
matter of course, the vital powers are indispensable, therefore
digestion may be considered as a chemical operation, directly
dependent on the laws of vitality, or of life; since the proper
consistency of the food depends, in a great measure, upon the
character of the solvents, while the secretion of these fluids, their
proper amount, together with the peculiar instinct--as it almost
seems to be--necessary to direct the stomach in its many functions,
are exclusively and entirely dependent on the laws and conditions of
life.


G.

As food is necessary to supply the waste and promote the growth of the
body, it follows that that will be the best adapted to the system
which contains the same chemical elements of which the body is
composed; viz., oxygen, hydrogen, carbon, and nitrogen. These elements
are found in greater or less quantity in all animal food, and in many
vegetable products. Hence, that article of food which contains all
these elements in a proper proportion will tend much more to the
growth and strength of the body than those kinds which are deficient
in one or more of them. Much experience on this point, and scientific
research, seem to show that a reasonable amount of animal food in
health tends to give greater strength of muscle, and a more general
sense of fulness, than in ordinary cases a vegetable diet is able to
do, owing to the presence of nitrogen in animal tissues. Yet there are
examples of the healthiest and strongest men, who live years without a
morsel of animal food; and the fact can only be accounted for, by
supposing that the system has the power to make the most economical
use of the little nitrogen offered to it in the food; or else that it
has by some means the power to abstract it from the atmosphere, and
transform it to the living animal substance.


H.

The proximate principles, which are the most important in nourishing
the body, are albumen and fibrin. These constitute the greater part of
all the softer animal tissues, and are also found in certain classes
of vegetables, such as peas, beans, lentils, and many seeds. Hence, in
many cases, a vegetable diet, especially if embracing any of those
articles, would be sufficient to sustain life, even if no animal food
should be eaten. But no animal can exist for a long time if permitted
only to eat substances destitute of nitrogen, as in the case of a dog
fed entirely on sugar, which lived but thirty days. And owing to this
fact, Baron Liebig proposes to call substances used for food,
containing nitrogen, "elements of nutrition," and those containing an
excess of carbon, "elements of respiration;" since, according to his
view, the food is necessary to support the growth of the body by
replacing the effete and worn-out particles with new matter, and also
to keep up the supply of fuel, in order to promote a sufficient degree
of heat in the system. Accordingly, under the first division would be
included all lean meats and vegetables, such as peas, &c.; while the
fat of animals, vegetable oils, sugars, tubers, (as the potato,) and
all other substances containing starch, would be included under the
latter division.


I.

This definition of exhalants is from the theory of Haller and others.
It is now believed that the fluids exude through the thin coats of the
blood vessels. This process is called _exosmose_, and is the
_exhalation_ of old physiologists.


J.

It is a well-established fact, in animal and vegetable physiology,
that membranes possess the property of allowing fluids and gases to
pass through them in either direction, and also to permit two fluids
to pass in opposite directions at the same time. This property is
designated _endosmose_ when a fluid passes from without a body inward;
and _exosmose_ when the reverse takes place. The first is called
_imbibition_. One of the most striking instances of this, in the human
system, is shown in the lungs, where carbonic acid and water pass out
through the mucous membrane of the bronchial tubes and air-cells; and
the oxygen of the air enters the blood through the same membrane. By
this process of imbibition, the oxygenation of the blood is much more
readily and faithfully accomplished; inasmuch, as by the immense
number of bronchial tubes and air-cells a larger quantity of blood is
exposed to a greater portion of air, than if the blood were directly
laid open to the atmosphere in a mass, or the air were immediately
transmitted through it.

Since the function of respiration is to free the system of superfluous
carbon and hydrogen, by union with the oxygen of the air, it follows
that the greater the amount of the products to be expelled, the larger
the quantity of oxygen will be required to effect this purpose, as we
find to be the case with those who consume large quantities of food.

The quantity of oxygen daily consumed through the lungs by an adult is
about 32.5 oz., and the carbon in the food 13.9 oz. But in order to
convert this whole amount of carbon into carbonic acid, which passes
off through the lungs and skin, 37 oz. of oxygen are required; the
remaining 4.5 oz. being absorbed by the skin. If the supply of food
remain the same, while the amount of oxygen in the inspired air is
diminished, the superfluous carbon will induce disease in the system,
as is the case of those persons who are limited in their supply of air
of a proper quality or quantity, and, consequently, have less appetite
for food than those who are abundantly supplied with air of the proper
standard of health; and in children, who proportionally consume more
food than adults, and who are more active, thereby causing a more
rapid circulation of blood, and, consequently, the removal of more
superfluous particles of matter.

In children we notice the need of air, by their disposition to be much
in the open air, and often inspiring more deeply than is common in
older persons. Also, if the carbon of the food does not have a
requisite supply of oxygen from the air, or other sources, the body
becomes emaciated, although nourishing food may be used. And on the
other hand, if there be a diminished supply of food, but an abundance
of atmospheric air, leanness and emaciation are sure to follow; owing
to the fact that if the oxygen has no waste carbon from the body to
unite with, it combines with the fat, and some other soft portions of
the body, which the Author of nature seems to have provided for this
very purpose; as is seen in the case of hibernating animals, who enter
their places of winter abode sleek and fat, but crawl out in the
spring not merely deprived of their fatty matter, but also with great
diminution of all the softer parts, which have given up their share of
carbon to supply animal heat. One important cause of emaciation in
febrile diseases is the greater rapidity of the pulse and respiration,
which consume more carbon than is afforded by the scanty supply of
food that is taken, although profuse perspiration, which almost always
occurs in some stages of fevers, greatly diminishes the full state of
the body.


K.

The theory of Baron Liebig concerning the change which the blood
experiences in color, in its passage through the lungs, meets with
the approbation of many physiologists, although there are some
important difficulties in the way of fully receiving it. A chemical
analysis of the blood shows it to be composed of albumen and
fibrin, together with some other substances, in small proportions, and
always perceptible traces of iron. He attributes the change in color
to the iron, as this substance enters into combination with carbon
and oxygen. For, as the blood passes through the trunks of the larger
vessels and capillaries, it receives the carbon from the tissues
which are continually transformed, and taking up the oxygen from the
arterialized blood, forms carbonic acid, which unites with the iron,
forming proto-carbonate of iron. This being of a gray color, he
supposes it to be that which, with the other impurities of the blood,
gives the venous blood the dark blue color. Then, as the blood
comes in contact with the oxygen, as it is returned and exposed to
this element in the lungs, the carbonic acid leaves the iron, which
has a stronger affinity for oxygen than for carbonic acid, and forms
the scarlet red peroxide of iron, that gives the characteristic
color to the arterial blood. After this, as the blood is sent out
through the smaller arteries and capillaries, it again gathers carbon
and other impurities from the system, and becomes the dark, venous
blood, thus completing the whole change of color in the circulation.


L.

As already mentioned, different articles of food have been divided
into the azotized and non-azotized, or those which contain nitrogen as
one of their constituents, and those which are nearly destitute of it.
Of these, according to Liebig, the azotized portions are simply to
supply the waste that is continually going on in the body, and promote
its growth in the early stages of existence, or, in other words, the
nutrient portion; while the sugar, starch, &c., are mainly of use in
the respiratory organs. The correctness of this view may be understood
from the fact, that the inhabitants in the colder regions of the earth
consume a much larger quantity of oil and fat than the residents of
hotter climates; and also those dwelling in the temperate zones can
eat with greater impunity a larger quantity of fat meats in the winter
than in the summer, there being then so much more demand for animal
heat than in the summer.


M.

The suggestion of using the bellows in asphyxia, is from the
directions of that distinguished and veteran surgeon, Valentine Mott,
of New York city. The directions in the first part of the paragraph
are the most practical, and best adapted to the wants of the
community.



GLOSSARY


AB-DUC´TOR. [L. _abduco_ to lead away.] A muscle which moves certain
parts, by separating them from the axis of the body.

AB-DO´MEN. [L. _abdo_, to hide.] That part of the body which lies
between the thorax and the bottom of the pelvis.

AB-DOM´IN-IS. Pertaining to the abdomen.

A-CE-TAB´U-LUM. [L. _acetum_, vinegar.] The socket for the head of the
thigh-bone; an ancient vessel for holding vinegar.

A-CE´TIC. [L. _acetum_, vinegar.] Relating to acetic acid. This is
always composed of oxygen, hydrogen, and carbon, in the same
proportion.

A-CHIL´LIS. A term applied to the tendon of two large muscles of the
leg.

A-CRO´MI-ON. [Gr. +akros+, _akros_, highest, and +ômos+, _omos_,
shoulder.] A process of the scapula that joins to the clavicle.

AD-DUC´TOR. [L. _adduco_, to lead to.] A muscle which draws one part
of the body toward another.

AL-BU-GIN´E-A. [L. _albus_, white.] A term applied to white textures.

AL-BU´MEN. [L. _albus_, white.] An animal substance of the same nature
as the white of an egg.

A-LU´MIN-UM. [L.] The name given to the metallic base of alumina.

AL´VE-O-LAR. [L. _alveolus_, a socket] Pertaining to the sockets of
the teeth.

AM-MO´NI-A. An alkali. It is composed of three equivalents of hydrogen
and one of nitrogen.

A-NAS´TO-MOSE. [Gr. +ana+, _ana_, through, and +stoma+, _stoma_,
mouth.] The communication of arteries and veins with each other.

AN-A-TOM´I-CAL. Relating to the parts of the body, when dissected or
separated.

A-NAT´O-MY. [Greek +ana+, _ana_, through, and +tomê+, _tomê_ a
cutting.] The description of the structure of animals. The word
_anatomy_ properly signifies dissection.

AN´GU-LI. [L. _angulus_, a corner.] A term applied to certain muscles
on account of their form.

AN-I-MAL´CU-LÆ. [L. _animalcula_, a little animal.] Animals that are
only perceptible by means of a microscope.

AN´NU-LAR. [L. _annulus_, a ring.] Having the form of a ring.

AN-TI´CUS. [L.] A term applied to certain muscles.

A-ORT´A. [Gr. +aortê+, _aortê_; from +aêr+, _aêr_, air, and +têreô+,
_têreo_, to keep.] The great artery that arises from the left
ventricle of the heart.

AP-O-NEU-RO´SIS. [Gr. +apo+, _apo_, from, and +neuron+, _neuron_, a
nerve.] The membranous expansions of muscles and tendons. The ancients
called every white tendon _neuron_, a nerve.

AP-PA-RA´TUS. [L. _apparo_, to prepare.] An assemblage of organs
designed to produce certain results.

AP-PEND´IX. [L., an addition.] Something appended or added.

A´QUE-OUS. [L. _aqua_, water.] Partaking of the nature of water.

A-RACH´NOID. [Gr. +arachnê+, _arachnê_, a spider, and +eidos+,
_eîdos_, form.] Resembling a spider's web. A thin membrane that
covers the brain.

AR´BOR. [L.] A tree. _Arbor vitæ._ The tree of life. A term applied to
a part of the cerebellum.

AR´TE-RY. [Gr. +aêr+, _aêr_, air, and +têreô+, _têreo_, to keep;
because the ancients thought that the arteries contained only air.] A
tube through which blood flows from the heart.

A-RYT-E´NOID. [Gr. +arytaina+, _arutaina_, a ewer, and +eidos+,
_eîdos_, form.] The name of a cartilage of the larynx.

AS-CEND´ENS. [L.] Ascending; rising.

AS-PHYX´I-A. [Gr. +a+, _a_, not, and +sphyxis+, _sphyxis_, pulse.]
Originally, want of pulse; now used for suspended respiration, or
apparent death.

AS-TRAG´A-LUS. [Gr.] The name of a bone of the foot. One of the tarsal
bones.

AUD-I´TION. [L. _audio_, to hear.] Hearing.

AUD-IT-O´RI-US. [L.] Pertaining to the organ of hearing.

AU´RI-CLE. [L. _auricula_, the external ear; from _auris_, the ear.] A
cavity of the heart.

AU-RIC´U-LAR. [L. _auricula_.] Pertaining to the auricle.

AX-IL´LA. [L.] The armpit.

AX´IL-LA-RY. Belonging or relating to the armpit.

A-ZOTE´. [Gr. +a+, _a_, not, and +zôê+, _zoê_, life.] Nitrogen. One of
the constituent elements of the atmosphere. So named because it will
not sustain life.


BEN-ZO´IC. _Benzoic acid._ A peculiar vegetable acid, obtained from
benzoin and some other balsams.

BI´CEPS. [L. _bis_, twice, and _caput_, a head.] A name applied to
muscles with two heads at one extremity.

BI-CUS´PIDS. [L. _bis_ and _cuspis_, a point.] Teeth that have two
points upon their crown.

BILE. [L. _bilis_.] A yellow, viscid fluid secreted by the liver.

BI-PEN´NI-FORM. [L. _bis_ and _penna_, a feather.] _Bipenniform
muscle._ Having fibres on each side of a common tendon.

BRACH´I-AL. [L. _brachium_.] Belonging to the arm.

BRE´VIS. [L.] _Brevis_, short; _brevior_, shorter.

BRONCH´I-A, -Æ. [L.] A division of the trachea that passes to the
lungs.

BRONCH´I-AL. Relating to the bronchia.

BRONCH-I´TIS. [L.] An inflammation of the bronchia.

BUC-CI-NA´TOR. [L. _buccinum_, a trumpet.] The name of a muscle of the
cheek, so named because used in blowing wind instruments.

BUR´SÆ MU-CO´SA. [L. _bursa_, a purse, and _mucosa_, viscous.] Small
sacs, containing a viscid fluid, situated about the joints, under
tendons.


CÆ´CUM. [L.] Blind; the name given to the commencement of the colon.

CALX, CAL´CIS. [L.] The heel-bone.

CAL´CI-UM. [L.] The metallic basis of lime.

CAP´IL-LA-RY. [L. _capillus_, a hair.] Resembling a hair; small.

CAP´SU-LAR. Pertaining to a capsule.

CAP´SULE. [L. _capsula_, a little chest.] A membranous bag, enclosing
a part.

CA´PUT. [L.] The head. _Caput coli._ The head of the colon.

CAR´BON. [L. _carbo_, a coal.] Pure charcoal. An elementary
combustible substance.

CAR-BON´IC. Pertaining to carbon.

CAR´DI-AC. [Gr. +kardia+, _kardia_, heart.] Relating to the heart, or
upper orifice of the stomach.

CAR´NE-A, -Æ. [L. _caro_, _carnis_, flesh.] Fleshy.

CA-ROT´ID. [Gr. +karos+, _karos_, lethargy.] The great arteries of the
neck that convey blood to the heart. The ancients supposed drowsiness
to be seated in these arteries.

CAR´PAL. [L. _carpus_, the wrist.] Relating to the wrist.

CAR´PUS, -I. [L.] The wrist.

CAR´TI-LAGE. [L. _cartilago_.] Gristle. A smooth, elastic substance,
softer than bone.

CAR-TI-LAG´IN-OUS. Pertaining to cartilage.

CAU-CA´SIAN. One of the races of men.

CA´VA. [L.] Hollow. _Vena cava._ A name given to the two great veins
of the body.

CEL´LU-LAR. [L. _cellula_, a little cell.] Composed of cells.

CER-E-BEL´LUM. [L.] The hinder and lower part of the brain, or the
little brain.

CER´E-BRAL. Pertaining to the brain.

CER´E-BRUM. [L.] The front and large part of the brain. The term is
sometimes applied to the whole contents of the cranium.

CER´E-BRO-SPI´NAL. Relating to the brain and spine.

CER´VIX. [L.] The neck.

CER´VI-CAL. Relating to the neck.

CHEST. [Sax.] The thorax; the trunk of the body from the neck to the
abdomen.

CHLO´RINE. [Gr. +chloros+, _chloros_, green.] _Chlorine gas_, so named
from its color.

CHOR´DA, -Æ. [L.] A cord. An assemblage of fibres.

CHO´ROID. [Gr. +chorion+, _chorion_.] A term applied to several parts
of the body that resemble the skin.

CHYLE. [Gr. +chulos+, _chulos_, juice.] A nutritive fluid, of a
whitish appearance, which is extracted from food by the action of the
digestive organs.

CHYL-I-FI-CA´TION. [_chyle_ and L. _facio_, to make.] The process by
which chyle is formed.

CHYME. [Gr. +chumos+, _chumos_, juice.] A kind of grayish pulp formed
from the food in the stomach.

CHYM-I-FI-CA´TION. [_chyme_ and L. _facio_, to make.] The process by
which chyme is formed.

CIL´IA-RY. [L. _cilia_, eyelashes.] Belonging to the eyelids.

CIN-E-RI´TIOUS. [L. _cinis_, ashes.] Having the color of ashes.

CLAV´I-CLE. [L. _clavicula_, from _clavis_, a key.] The collar-bone;
so called from its resemblance in shape to an ancient key.

CLEI´DO. A term applied to some muscles that are attached to the
clavicle.

CO-AG´U-LUM. [L.] A coagulated mass, a clot of blood.

COC´CYX. [Gr.] An assemblage of bones joined to the sacrum.

COCH´LE-A. [Gr. +kochlô+, _kochlo_, to twist; or L. _cochlea_, a
screw.] A cavity of the ear resembling in form a snail shell.

CO´LON. [Gr.] A portion of the large intestine.

CO-LUM´NA, -Æ.[L.] A column or pillar.

COM-MU´NIS. [L.] A name applied to certain muscles.

COM-PLEX´US. [L. _complector_, to embrace.] The name of a muscle that
embraces many attachments.

COM-PRESS´OR. [L. _con_, together, and _premo_, _pressus_, to press.]
A term applied to some muscles, that compress the parts to which they
are attached.

CON´DYLE. [Gr. +kondulos+, _kondulos_, a knuckle, a protuberance.] A
prominence on the end of a bone.

CON-JUNC-TI´VA. [L. _con_, together, and _jungo_, to join.] The
membrane that covers the anterior part of the globe of the eye.

COP´PER. A metal of a pale, red color, tinged with yellow.

COR-A´COID. [Gr. +korax+, _korax_, a crow, and +eidos+, _eîdos_,
form.] A process of the scapula shaped like the beak of a crow.

CO´RI-ON. [Gr. +chorion+, _chorion_, skin.] The true skin.

CORN´E-A. [L. _cornu_, a horn.] The transparent membrane in the fore
part of the eye.

COS´TA. [L. _costa_, a coast, side, or rib.] A rib.

CRIB´RI-FORM. [L. _cribrum_, a sieve, and _forma_, form.] A plate of
the ethmoid bone, through which the olfactory nerve passes to the
nose.

CRI´COID. [Gr. +krikos+, _krikos_, a ring, and +eidos+, _eîdos_,
form.] A name given to a cartilage of the larynx, from its form.

CRYS´TAL-LINE. [L. _crystallinus_, consisting of crystal.] _Crystalline
lens._ One of the humors of the eye. It is convex, white, firm, and
transparent.

CU´BI-TUS, -I. [L. _cubitus_, the elbow.] One of the bones of the
forearm, also called the _ulna_.

CU´BOID. [Gr. +kubos+, _kubos_, a cube, and +eidos+, _eîdos_, form.]
Having nearly the form of a cube.

CU-NE´I-FORM. [L. _cuneus_, a wedge.] The name of bones in the wrist
and foot.

CUS´PID. [L. _cuspis_, a point.] Having one point.

CU-TA´NE-OUS. [L. _cutis_, skin.] Belonging to the skin.

CU´TI-CLE. [L. _cutis_.] The external layer of the skin.

CU´TIS VE´RA. [L. _cutis_, and _vera_, true.] The internal layer of
the skin; the true skin.


DEL´TOID. [Gr. +delta+, _delta_, the Greek letter +Delta+, and
+eidos+, _eîdos_, form.] The name of a muscle, that resembles in form
the Greek letter +Delta+.

DENS. [L.] A tooth.

DENT´AL. [L. _dens_, tooth.] Pertaining to the teeth.

DE-PRESS´OR. [L.] The name of a muscle that draws down the part to
which it is attached.

DERM´OID. [Gr. +derma+, _derma_, the skin, and +eidos+, _eîdos_,
form.] Resembling skin.

DE-SCEND´ENS. [L. _de_ and _scando_, to climb.] Descending, falling.

DI´A-PHRAGM. [Gr. +diaphragma+, _diaphragma_, a partition.] The
midriff; a muscle separating the chest from the abdomen.

DI-AR-RHOE´A. [Gr. +diarreô+, _diarrheo_, to flow through.] A morbidly
frequent evacuation of the intestines.

DI-AS´TO-LE. [Gr. +diastellô+, _diastello_, to put asunder.] The
dilatation of the heart and arteries when the blood enters them.

DI-GES´TION. [L. _digestio_.] The process of dissolving food in the
stomach, and preparing it for circulation and nourishment.

DIG-I-TO´RUM. [L. _digitus_, a finger.] A term applied to certain
muscles of the extremities.

DOR´SAL. [L. _dorsum_, the back.] Pertaining to the back.

DU-O-DE´NUM. [L. _duodenus_, of twelve fingers' breadth.] The first
portion of the small intestine.

DU´RA MA´TER. [L. _durus_, hard, and _mater_, mother.] The outermost
membrane of the brain.

DYS´EN-TER-Y. [Gr. +dys+, _dûs_, bad, and +enteria+, _enteria_,
intestines.] A discharge of blood and mucus from the intestines
attended with tenesmus.

DYS-PEP´SI-A. [Gr. +dys+, _dûs_, bad, and +peptô+, _pepto_, to
digest.] Indigestion, or difficulty of digestion.


EN-AM´EL. [Fr.] The smooth, hard substance which covers the crown or
visible part of a tooth.

EP-I-DERM´IS. [Gr. +epi+, _epi_, upon, and +derma+, _derma_, the
skin.] The scarf-skin; the cuticle.

EP-I-GLOT´TIS. [Gr. +epi+, _epi_, upon, and +glôtta+, _glôtta_, the
tongue.] One of the cartilages of the glottis.

EU-STA´CHI-AN TUBE. A channel from the fauces to the middle ear, named
from Eustachius, who first described it.

EX´CRE-MENT. [L. _excerno_, to separate.] Matter excreted and ejected;
alvine discharges.

EX-CRE-MEN-TI´TIAL. Pertaining to excrement.

EX´CRE-TO-RY. A little duct or vessel, destined to receive secreted
fluids, and to excrete or discharge them; also, a secretory vessel.

EX-HA´LANT. [L. _exhalo_, to send forth vapor.] Having the quality of
exhaling or evaporating.

EX-TENS´OR. [L.] A name applied to a muscle that serves to extend any
part of the body; opposed to _Flexor_.


FA´CIAL. [L. _facies_, face.] Pertaining to the face.

FALX. [L. _falx_, a scythe.] A process of the dura mater shaped like a
scythe.

FAS´CI-A. [L. _fascia_, a band.] A tendinous expansion or aponeurosis.

FAS-CIC´U-LUS, -LI. [L. _fascis_, a bundle.] A little bundle.

FAUX, -CES. [L.] The top of the throat.

FEM´O-RAL. Pertaining to the femur.

FEM´O-RIS. A term applied to muscles that are attached to the femur.

FE´MUR. [L.] The thigh-bone.

FE-NES´TRA, -UM. [L. _fenestra_, a window.] A term applied to some
openings into the internal ear.

FI´BRE. [L. _fibra_.] An organic filament, or thread, which enters
into the composition of every animal and vegetable texture.

FI´BRIN. A peculiar organic substance found in animals and vegetables;
it is a solid substance, tough, elastic, and composed of thready
fibres.

FI´BROUS. Composed or consisting of fibres.

FI´BRO-CAR´TI-LAGE. An organic tissue, partaking of the nature of
fibrous tissue and that of cartilage.

FIB´U-LA. [L., a clasp.] The outer and lesser bone of the leg.

FIB´U-LAR. Belonging to the fibula.

FIL´A-MENT. [L. _filamenta_, threads.] A fine thread, of which flesh,
nerves, skin, &c., are composed.

FLEC´TION. [L. _flectio_.] The act of bending.

FOL´LI-CLE. [L. _folliculus_, a small bag.] A gland; a little bag in
animal bodies.

FORE´ARM. The part of the upper extremity between the elbow and hand.

FOS´SA. [L., a ditch.] A cavity in a bone, with a large aperture.

FRÆ´NUM. [L., a bridle.] _Frænum linguæ._ The bridle of the tongue.

FUNC´TION. [L. _fungor_, to perform.] The action of an organ or system
of organs.

FUN´GI-FORM. [L. _fungus_ and _forma_.] Having terminations like the
head of a fungus, or a mushroom.


GAN´GLI-ON, -A. [Gr.] An enlargement in the course of a nerve.

GAS´TRIC. [Gr. +gastêr+, _gastêr_, the stomach.] Belonging to the
stomach.

GAS-TROC-NE´MI-US. [Gr. +gastêr+, _gastêr_, the stomach, and +knêmê+,
_knêmê_, the leg.] The name of large muscles of the leg.

GEL´A-TIN. [L. _gelo_, to congeal.] A concrete animal substance,
transparent and soluble in water.

GLE´NOID. [Gr. +glênê+, _glênê_, a cavity.] A term applied to some
articulate cavities of bones.

GLOS´SA. [Gr.] The tongue. Names compounded with this word are applied
to muscles of the tongue.

GLOS´SO-PHA-RYN´GI-AL. Relating to the tongue and pharynx.

GLOT´TIS. [Gr.] The narrow opening at the upper part of the larynx.

GLU´TE-US. [Gr.] A name given to muscles of the hip.


HEM´OR-RHAGE. [Gr. +haima+, _haima_, blood and +rêgnuô+, _rêgnuo_, to
burst.] A discharge of blood from an artery or vein.

HU´MER-US. [L.] The bone of the arm.

HY´A-LOID. [Gr.] A transparent membrane of the eye.

HY´DRO-GEN. [Gr. +hydôr+, water, and +gennaô+, to generate.] A gas
which constitutes one of the elements of water.

HY´GI-ENE. [Gr. +hugieinon+, _hugieînon_, health.] The part of
medicine which treats of the preservation of health.

HY´OID. [Gr. +u+ and +eidos+, _eîdos_, shape.] A bone of the tongue
resembling the Greek letter upsilon in shape.

HY-OID´E-US. Pertaining to the hyoid bone.

HY´PO-GLOS´SAL. Under the tongue. The name of a nerve of the tongue.


IL´E-UM. [Gr. +eilô+, _eilô_, to wind.] A portion of the small
intestines.

IL´I-AC. [From the above.] The flank; pertaining to the small
intestine.

IL´I-UM. The haunch-bone.

IN-CI´SOR. [L. _incido_, to cut.] A front tooth that cuts or divides.

IN´DEX. [L. _indico_, to show.] The fore-finger; the pointing finger.

IN-NOM-I-NA´TA. [L. _in_, not, and _nomen_, name.] Parts which have no
proper name.

IN-OS´CU-LATE. [L. _in_ and _osculatus_, from _osculor_, to kiss.] To
unite, as two vessels at their extremities.

IN´TER. [L.] Between.

IN-TER-COST´AL. [L. _inter_, between, and _costa_, a rib.] Between the
ribs.

IN-TER-NO´DI-I. [L. _inter_, between, and _nodus_, knot.] A term
applied to some muscles of the forearm.

IN-TER-STI´TIAL. [L. _inter_, between, and _sto_, to stand.]
Pertaining to or containing interstices.

IN-TES´TINES. [L. _intus_, within.] The canal that extends from the
stomach to the anus.

I´RIS. [L., the rainbow.] The colored circle that surrounds the pupil
of the eye.

I´VO-RY. A hard, solid, fine-grained substance of a fine white color;
the tusk of an elephant.


JE-JU´NUM. [L., empty.] A portion of the small intestine.

JU´GU-LAR. [L. _jugulum_, the neck.] Relating to the throat. The great
veins of the neck.


LA´BI-UM, LA´BI-I. [L.] The lips.

LAB´Y-RINTH. [Gr.] The internal ear, so named from its many windings.

LACH´RY-MAL. [L. _lachryma_, a tear.] Pertaining to tears.

LAC´TE-AL. [L., _lac_, milk.] A small vessel or tube of animal bodies
for conveying chyle from the intestine to the thoracic duct.

LAM´I-NA, -Æ. [L.] A plate, or thin coat lying over another.

LAR´YNX. [Gr. +larunx+, _larunx_.] The upper part of the windpipe.

LAR-YN-GI´TIS. Inflammation of the larynx.

LA-TIS´SI-MUS, -MI. [L., superlative of _latus_, broad.] A term
applied to some muscles.

LE-VA´TOR. [L. _levo_, to raise.] A name applied to a muscle that
raises some part.

LIG´A-MENT. [L. _ligo_, to bind.] A strong, compact substance serving
to bind one bone to another.

LIN´E-A, -Æ. [L.] A line.

LIN´GUA, -Æ. [L.] A tongue.

LIV´ER. The name of one of the abdominal organs, the largest gland in
the system. It is situated below the diaphragm, and secretes the
bile.

LOBE. A round projecting part of an organ.

LON´GUS, LON´GI-OR. [L., long, longer.] A term applied to several
muscles.

LUM´BAR. [L. _lumbus_, the loins.] Pertaining to the loins.

LYMPH. [L. _lympha_, water.] A colorless fluid in animal bodies, and
contained in vessels called lymphatics.

LYM-PHAT´IC. A vessel of animal bodies that contains or conveys
lymph.


MAG-NE´SI-UM. The metallic base of magnesia.

MAG´NUS, -NA, -NUM. [L., great.] A term applied to certain muscles.

MA´JOR. [L., greater.] Greater in extent or quantity.

MAN´GA-NESE. A metal of a whitish gray color.

MAR´ROW. [Sax.] A soft, oleaginous substance, contained in the
cavities of bones.

MAS-SE´TER. [Gr. +massaomai+, _massaomai_, to chew.] The name of a
muscle of the face.

MAS´TI-CATE, MAS-TI-CA´TION. [L. _mastico_.] To chew; the act of
chewing.

MAS´TOID. [Gr. +mastos+, _mastos_, breast, and +eidos+, _eîdos_,
form.] the name of a process of the temporal bone behind the ear.

MAS-TOID´E-US. A name applied to muscles that are attached to the
mastoid process.

MAX-IL´LA. [L.] The jaw-bone.

MAX´IL-LA-RY. Pertaining to the jaw.

MAX´I-MUS, -UM. [L., superlative of _magnus_, great.] A term applied
to several muscles.

ME-A´TUS. [L. _meo_, to go.] A passage or channel.

ME-DI-AS-TI´NUM. A membrane that separates the chest into two parts.

ME´DI-UM, -A. [L.] The space or substance through which a body passes
to any point.

MED´UL-LA-RY. [L., _medulla_, marrow.] Pertaining to marrow.

ME-DUL´LA OB-LON-GA´TA. Commencement of the spinal cord.

ME-DUL´LA SPI-NA´LIS. The spinal cord.

MEM´BRA-NA. A membrane; a thin, white, flexible skin formed by fibres
interwoven like net-work.

MEM´BRA-NOUS. Relating to membrane.

MES´EN-TER-Y. [Gr. +mesos+, _mesos_, the middle, and +enteron+,
_enteron_, the intestine.] The membrane in the middle of the
intestines, by which they are attached to the spine.

MES-EN-TER´IC. Pertaining to the mesentery.

MET-A-CAR´PAL. Relating to the metacarpus.

MET-A-CAR´PUS. [Gr. +meta+, _meta_, after, and +karpos+, _karpos_,
wrist.] The part of the hand between the wrist and fingers.

MET-A-TAR´SAL. Relating to the metatarsus.

MET-A-TAR´SUS. [Gr. +meta+, _meta_, after, and +tarsos+, _tarsos_, the
tarsus.] The instep. A term applied to seven bones of the foot.

MID´RIFF. [Sax. _mid_, and _hrife_, the belly.] See DIAPHRAGM.

MIN´I-MUS, -I. [L.] The smallest. A term applied to several muscles.

MI´NOR. [L.] Less, smaller. A term applied to several muscles.

MI´TRAL. [L. _mitra_, a mitre.] The name of the valves in the left
side of the heart.

MO-DI´O-LUS. [L. _modus_, a measure.] A cone in the cochlea around
which the membranes wind.

MO´LAR. [L. _mola_, a mill.] The name of some of the large teeth.

MOL´LIS. [L.] Soft.

MO´TOR, -ES. [L. _moveo_, to move.] A mover. A term applied to certain
nerves.

MU´COUS. Pertaining to mucus.

MU´CUS. A viscid fluid secreted by the mucous membrane, which it
serves to moisten and defend.

MUS´CLE. A bundle of fibres enclosed in a sheath.

MUS´CU-LAR. Relating to a muscle.

MY-O´DES. A term applied to certain muscles of the neck.


NA´SAL. Relating to the nose.

NA´SUS. [L., the nose.] The nostrils.

NERVE. An organ of sensation and motion in animals.

NERV´OUS. Relating to the nerves.

NEU-RI-LEM´A. [Gr. +neuron+, _neuron_, a nerve, and +lemma+, _lema_, a
sheath.] The sheath or covering of a nerve.

NI´GRUM. [L.] Black.

NI´TRO-GEN. That element of the air which is called azote.

NU-TRI´TION. The art or process of promoting the growth, or repairing
the waste of the system.


OC-CIP-I-TA´LIS. Pertaining to the back part of the head.

OC´CI-PUT. [L. _ob_ and _caput_, the head.] The hinder part of the
head.

OC-U-LO´RUM. Of the eyes.

OC´ULUS, -I. [L.] The eye.

OE-SOPH´A-GUS. [Gr. +oiô+, _oiô_, to carry, and +phagô+, _phago_, to
eat.] The name of the passage through which the food passes from the
mouth to the stomach.

O-LEC´RA-NON. [Gr. +ôlene+, _ôlene_, the cubit, and +kranon+,
_kranon_, the head.] The elbow; the head of the ulna.

OL-FACT´O-RY. [L. _oleo_, to smell, and _facio_, to make.] Pertaining
to smelling.

O-MEN´TUM. [L.] The caul.

O´MO. [Gr. +ômos+, _ômos_, the shoulder.] Names compounded of this
word are applied to muscles attached to the shoulder.

OPH-THAL´MIC. [Gr. +ophthalmos+, _ophthalmos_, the eye.] Belonging to
the eye.

OP-PO´NENS. That which acts in opposition to something. The name of
two muscles of the hand.

OP´TI-CUS, OP´TIC. [Gr. +optomai+, _optomai_, to see.] Relating to the
eye.

OR-BIC´U-LAR. [L. _orbis_, a circle.] Circular.

OR-BIC-U-LA´RIS. A name applied to several muscles.

OR´GAN. A part of the system destined to exercise some particular
function.

OR´I-GIN. Commencement; source.

OS. [L.] A bone; the mouth of any thing.

O´RIS. [L. _os_, _oris_.] Of the mouth.

OS HY-OID´ES. [Gr. See HYOID.] The name of the bone at the base of the
tongue.

OS´MA-ZOME. [Gr. +osmê+, _osmê_, smell, and +zômos+, _zômos_, broth.]
A principle obtained from animal fibre which gives the peculiar taste
to broth.

OS´SA. [L., plural of _os_, bone.] Bones.

OS´SE-OUS. Pertaining to bones.

OS-SI-FI-CA´TION. The formation of bones in animals.

OS´SI-FY. [L. _ossa_, bones, and _facio_, to make.] To convert into
bone.

OS´SIS. Of a bone.

O-VA´LE. [L.] The shape of an egg.

OX-AL´IC. Pertaining to sorrel. _Oxalic acid_ is the acid of sorrel.
It is composed of two equivalents of carbon and three of oxygen.

OX´Y-GEN. A permanently elastic fluid invisible and inodorous. One of
the components of atmospheric air.


PA-LA´TUM. [L.] The palate; the roof of the mouth.

PAL-PE-BRA´RUM. [L. _palpebra_, the eyelid.] Of the eyelids.

PAL´MAR. [L. _palma_, the palm.] Belonging to the hand.

PAL-MA´RIS. A term applied to some muscles attached to the palm of the
hand.

PAN´CRE-AS. [Gr. +pan+, _pan_, all, and +kreas+, _kreas_, flesh.] The
name of one of the digestive organs.

PAN-CRE-AT´IC. Belonging to the pancreas.

PA-PIL´LA, -Æ. [L.] Small conical prominences.

PA-RAL´Y-SIS. Abolition of function whether of intellect, sensation,
or motion.

PA-REN´CHY-MA. [Gr. +parencheô+, _parengcheô_, to pour through.] The
substance contained between the blood vessels of an organ.

PA-ROT´ID. [Gr. +para+, _para_, near, and +ôtos+, _ôtos_, the gen. of
+ous+, _ous_, the ear.] The name of the largest salivary gland.

PA-TEL´LA, -Æ. [L.] The knee-pan.

PA-THET´I-CUS, -CI. [Gr. +pathos+, _pathos_, passion.] The name of the
fourth pair of nerves.

PEC´TUS. [L.] The chest.

PEC´TO-RAL. Pertaining to the chest.

PEC-TO-RA´LIS. Belonging to the chest.

PE´DIS. [L., gen. of _pes_, the foot.] Of the foot.

PEL´I-TONGS. A term applied to masses of fat.

PEL´LI-CLE. [L., dim. of _pellis_, the skin.] A thin skin or film.

PEL´VIC. Relating to the pelvis.

PEL´VIS. [L.] The basin formed by the large bones at the lower part of
the abdomen.

PEN´NI-FORM. [L. _penna_, a feather.] Having the form of a feather, or
quill.

PER-I-CAR´DI-UM. [Gr. +peri+, _peri_, around, and +kardia+, _kardia_,
the heart.] A membrane that encloses the heart.

PER-I-CHON´DRI-UM. [Gr. +peri+, _peri_, around, and +chondros+,
_chondros_, cartilage.] A membrane that invests cartilage.

PER-I-CRA´NI-UM. [Gr. +peri+, and +kranion+, _kranion_, the cranium.]
A membrane that invests the skull.

PER´MA-NENT. Durable; lasting.

PER-I-STAL´TIC. [Gr. +peristellô+, _peristello_, to involve.] A
movement like the crawling of a worm.

PER-SPI-RA´TION. [L. _per_, through, and _spiro_, to breathe.] The
excretion from the skin.

PHAL´ANX, -GES. [Gr. +phalanx+, _phalanx_, an army.] Three rows of
small bones forming the fingers or toes.

PHA-LAN´GI-AL. Belonging to the fingers or toes.

PHA-RYN´GE-AL. Relating to the pharynx.

PHAR´YNX. [Gr. +pharunx+, _pharunx_.] The upper part of the
oesophagus.

PHOS´PHOR-US. [Gr. +phôs+, _phôs_, the light, and +pherô+, _pherô_, to
bear.] A combustible substance, of a yellowish color, semi-transparent,
resembling wax.

PHREN´IC. [Gr. +phrên+, _phrên_, the mind.] Belonging to the
diaphragm.

PHYS-I-OL´O-GY. [Gr. +phusis+, _phusis_, nature, and +logos+, _logos_,
a discourse.] The science of the functions of the organs of animals
and plants.

PI´A MA´TER. [L., good mother.] The name of one of the membranes of
the brain.

PIG-MEN´TUM. [L.] Paint; a preparation of colors.

PIN´NA. [L., a wing.] A part of the external ear.

PLA-TYS´MA. [Gr. +platus+, _platûs_, broad.] A muscle of the neck.

PLEU´RA, -Æ. [Gr. +pleura+, _pleura_, the side.] A thin membrane that
covers the inside of the thorax, and also forms the exterior coat of
the lungs.

PLEU´RAL. Relating to the pleura.

PLEX´US. [L. _plecto_, to weave together.] Any union of nerves,
vessels, or fibres, in the form of net-work.

PNEU-MO-GAS´TRIC. [Gr. +pneumôn+, _pneumôn_, the lungs, and +gastêr+,
_gastêr_, the stomach.] Belonging to both the stomach and lungs.

POL´LI-CIS. [L.] A term applied to muscles attached to the fingers and
toes.

PONS. [L.] A bridge. _Pons varolii._ A part of the brain formed by the
union of the crura cerebri and cerebelli.

POP-LIT-E´AL. [L. _poples_, the ham.] Pertaining to the ham or
knee-joint. A name given to various parts.

POS´TI-CUS. [L.] Behind; posterior. A term applied to certain
muscles.

POR´TI-O DU´RA. [L., hard portion.] The facial nerve; 8th pair.

POR´TI-O MOL´LIS. [L., soft portion.] The auditory nerve; 7th pair.

PO-TAS´SI-UM. [L.] The metallic basis of pure potash.

PRO-BOS´CIS. [Gr. +pro+, _pro_, before, and +boskô+, _boskô_, to
feed.] The snout or trunk of an elephant or other animal.

PROC´ESS. A prominence or projection.

PRO-NA´TOR. [L. _pronus_, turned downward.] The muscle of the forearm
that moves the palm of the hand downward.

PSO´AS. [Gr. +psoai+, _psoai_, the loins.] The name of two muscles of
the leg.

PUL-MON´IC.    }
               }
PUL´MO-NA-RY.  }  [L. _pulmo_, the lungs.] Belonging or
               }  relating to the lungs.
PUL-MO-NA´LIS. }

PU´PIL. A little aperture in the centre of the iris, through which the
rays of light pass to the retina.

PY-LOR´IC. Pertaining to the pylorus.

PY-LOR´US. [Gr. +pulôros+, _pulôros_, a gate keeper.] The lower
orifice of the stomach, with which the duodenum connects.


RA´DI-US. [L., a ray, a spoke of a wheel.] The name of one of the
bones of the forearm.

RA-DI-A´LIS. Radial; belonging to the radius.

RA´DI-ATE. Having lines or fibres that diverge from a point.

RA´MUS. [L.] A branch. A term applied to the projections of bones.

REC-RE-MEN-TI´TIAL. [L. _re_, again, and _cerno_, to secrete.]
Consisting of superfluous matter separated from that which is
valuable.

REC´TUM. The third and last portion of the intestines.

REC´TUS, -I. [L.] Straight; erect. A term applied to several muscles.

RE-SID´U-AL. Pertaining to waste matter.

RE-SID´U-UM. [L.] Waste matter. The fæces.

RES-PI-RA´TION. [L. _re_, again, and _spiro_, to breathe.] The act of
breathing. Inspiring air into the lungs and expelling it again.

RE-SPI´RA-TO-RY. Pertaining to respiration; serving for respiration.

RET´I-NA. [L., _rete_, a net.] The essential organ of sight. One of
the coats of the eye, formed by the expansion of the optic nerve.

RO-TUN´DUM, -A. [L.] Round; circular.

RU´GA, -Æ. [L.] A wrinkle; a fold.


SAC´CU-LUS. [L., dim. of _saccus_, a bag.] A little sac.

SA´CRAL. Pertaining to the sacrum.

SA´CRUM. [L., sacred.] The bone which forms the posterior part of the
pelvis, and is a continuation of the spinal column.

SA-LI´VA. [L.] The fluid which is secreted by the salivary glands,
which moistens the food and mouth.

SAL´I-VA-RY. That which belongs to the saliva.

SAN´GUIN-E-OUS. [L. _sanguis_, the blood.] Bloody; abounding with
blood; plethoric.

SAR-TO´RI-US. [L. _sartor_, a tailor.] A term applied to a muscle of
the thigh.

SCA´LA, -Æ. [L., a ladder.] Cavities of the cochlea.

SCA-LE´NUS. [Gr. +skalênos+, _skalênos_, unequal.] A term applied to
some muscles of the neck.

SCAPH´OID. [Gr. +skaphê+, _skaphê_, a little boat.] The name applied
to one of the wrist-bones.

SCAP´U-LA. [L.] The shoulder-blade.

SCAP´U-LAR. Relating to the scapula.

SCARF-SKIN. The outer, thin integument of the body; the cuticle.

SCI-AT´IC. [Gr., pertaining to the loins.] The name of the large nerve
of the loins and leg.

SCLE-ROT´IC. [Gr. +sklêros+, _sklêros_, hard.] A membrane of the eye.

SE-BA´CEOUS. [L., _sebum_, tallow.] Pertaining to fat; unctuous
matter.

SE-CRE´TION. The act of secerning; the act of producing from the blood
substances different front the blood itself, as bile, saliva. The
matter secreted, as mucus, bile, &c.

SE-CRE´TO-RY. Performing the office of secretion.

SE-CUN´DUS. Second. A term applied to certain muscles.

SEM-I-CIR´CU-LAR. Having the form of a half circle. The name of a part
of the ear.

SEM-I-TEN-DI-NO´SUS. [L. _semi_, half and _tendo_, a tendon.] The name
of a muscle.

SEP´TUM. [L.] A membrane that divides two cavities from each other.

SE´ROUS. Thin; watery. Pertaining to serum.

SE´RUM. [L.] The thin, transparent part of blood.

SER-RA´TUS. [L. _serro_, to saw.] A term applied to some muscles of
the trunk.

SIG´MOID. [Gr.] Resembling the Greek +s+, sigma.

SI-LI´CI-UM. A term applied to one of the earths.

SI´NUS. [L., a bay.] A cavity, the interior of which is more expanded
than the entrance.

SKEL´E-TON. [Gr. +skellô+, _skellô_, to dry.] The aggregate of the
hard parts of the body; the bones.

SO´DI-UM. The metallic base of soda

SPHINC´TER. [Gr. +sphingô+, _sphingo_, to restrict.] A muscle that
contracts or shuts an orifice.

SPI´NAL CORD. A prolongation of the brain.

SPI-NA´LIS. Relating to the spine.

SPINE. A thorn. The vertebral column; back-bone.

SPI´NOUS. Belonging to the spinal column.

SPLEEN. The milt. It is situated in the abdomen, and attached to the
stomach.

SPLEN´IC. Relating to the spleen.

SPLE´NI-US. The name of a muscle of the neck.

STA´PES. The name of one of the small bones of the ear.

STER´NUM. The breast-bone. The bone that forms the front of the chest
from the neck to the stomach.

STOM´ACH. The principal organ of the digestive apparatus.

STRA´TUM. [L. _sterno_, to stew.] A bed; a layer.

STY´LOID. [L. _stylus_, a pencil.] An epithet applied to processes
that resemble a style, a pen.

SUB-CLA´VI-AN. [L. _sub_, under, and _clavis_, a key.] Situated under
the clavicle.

SUB-LI´MIS. High in place.

SUB-LIN´GUAL. [L. _sub_, under, and _lingua_, the tongue.] Situated
under the tongue.

SUB-MAX´IL-LA-RY. [L. _sub_, under, and _maxilla_, the jaw-bone.]
Located under the jaw.

SUL´PHUR. A simple, mineral substance, of a yellow color, brittle,
insoluble in water, but fusible by heat.

SU-PE-RI-O´RIS. A term applied to certain muscles.

SU-PI-NA´TOR. [L.] A muscle that turns the palm of the hand upward.

SUT´URE. [L. _suo_, to sew.] The seam or joint that unites the bones
of the skull.

SYN-O´VI-A. [Gr. +syn+, _sûn_, with, and +ôon+, _ôon_, an egg.] The
fluid secreted into the cavities of joints for the purpose of
lubricating them.

SYN-O´VI-AL. Pertaining to synovia.

SYS´TEM. An assemblage of organs composed of the same tissues, and
intended for the same functions.

SYS-TEM´IC. Belonging to the general system.

SYS´TO-LE. [Gr. +systellô+, _sûstellô_, to contract.] The contraction
of the heart and arteries for expelling the blood and carrying on the
circulation.


TAR´SAL. Relating to the tarsus.

TAR´SUS. [L.] The posterior part of the foot.

TEN´DON. [Gr. +teinô+, _teino_, to stretch.] A hard, insensible cord,
or bundle of fibres, by which a muscle is attached to a bone.

TEN´DI-NA, -Æ. Pertaining to a tendon.

TENS´OR. A muscle that extends a part.

TEN-TAC´U-LA, -Æ. [L. _tento_, to seize.] A filiform process or organ
on the bodies of various animals.

TEN-TO´RI-UM. [L. _tendo_, to stretch.] A process of the dura mater
which lies between the cerebrum and cerebellum.

TE´RES. [L. _teres_, round.] An epithet given to many organs, the
fibres of which are collected in small bundles.

THO´RAX. [Gr.] That part of the skeleton that composes the bones of
the chest. The cavity of the chest.

THO-RAC´IC. Relating to the chest.

THY´ROID. [Gr. +thureos+, _thureos_, a shield.] Resembling a shield. A
cartilage of the larynx.

TIB´I-A. [L., a flute.] The large bone of the leg.

TIB-I-A´LIS, TIB´I-AL. Relating to the tibia.

TIS´SUE. The texture or organization of parts.

TON´SIL. [L.] A glandular body in the throat or fauces.

TRA´CHE-A. [Gr. +trachus+, _trachus_, rough.] The windpipe.

TRA´CHE-AL. Belonging to the trachea.

TRANS-VERSE´, TRANS-VER-SA´LIS. Lying in a cross direction.

TRA-PE´ZI-US. The name of a muscle, so called from its form.

TRI´CEPS. [L. _tres_, three, and _caput_, head.] Three. A name given
to muscles that have three attachments at one extremity.

TRI-CUS´PID. [L. _tres_, three, and _cuspis_, point.] The triangular
valves in the right side of the heart.

TROCH´LE-A. [Gr. +trochalia+, _trochalia_, a pulley.] A pulley-like
cartilage, over which the tendon of a muscle of the eye passes.

TROCH-LE-A´RIS. The name of a muscle of the eye.

TRUNK. The principal part of the body, to which the limbs are
articulated.

TU´BER-CLE. [L. _tuber_, a bunch.] A small push, swelling, or tumor,
on animal bodies.

TU-BER-OS´I-TY. The state of being knobbed or protuberant.

TYM´PAN-UM. [L.] The middle ear.


UL´NA. [L.] A bone of the forearm.

UL´NAR, UL-NA´RIS. Relating to the ulna.

U´RIC. [Gr. +ouron+, _ouron_, urine.] An acid contained in urine, and
in gouty concretions.

U-VE´A. [L. _uva_, a grape.] Resembling grapes. A thin membrane of the
eye.

U´VU-LA. A soft body, suspended from the palate, near the aperture of
the nostrils, over the glottis.


VAC´CINE VI´RUS. [L. _vacca_, a cow, _virus_, poison.] Pertaining to
cows; derived from cows.

VALVE. Any membrane, or doubling of any membrane, which prevents
fluids from flowing back in the vessels and canals of the animal
body.

VAL´VU-LA, -Æ. A valve.

VAS´CU-LAR. [L. _vasculum_, a vessel.] Pertaining to vessels;
abounding in vessels.

VAS´TUS. [L.] Great, vast. Applied to some large muscles.

VEINS. Vessels that convey blood to the heart.

VE´NOUS. Pertaining to veins.

VEN´TRI-CLE. [L. _venter_, the stomach.] A small cavity of the animal
body.

VEN-TRIC´U-LAR. Relating to ventricles.

VER-MIC´U-LAR. [L. _vermiculus_, a little worm.] Resembling the
motions of a worm.

VERM-I-FORM´IS. [L. _vermis_, a worm, and _forma_, form.] Having the
form and shape of a worm.

VERT´E-BRA, -Æ. [L. _verto_, to turn.] A joint of the spinal column.

VERT´E-BRAL. Pertaining to the joints of the spinal column.

VES´I-CLE. [L. _vesica_, a bladder.] A little bladder, or a portion of
the cuticle separated from the cutis vera and filled with serum.

VES´TI-BULE. [L.] A porch of a house. A cavity belonging to the ear.

VIL´LI. [L.] Fine, small fibres.

VI´RUS. [L. poison.] Foul matter of an ulcer; poison.

VI´TAL. [L. _vita_, life.] Pertaining to life.

VIT´RE-OUS. [L. _vitrum_, glass.] Belonging to glass. A humor of the
eye.

VO´LAR. [L. _vola_, the hollow of the hand or foot.] Belonging to the
palm of the hand.

VO´MER. [L. a ploughshare.] One of the bones of the nose.


ZYG-O-MAT´I-CUS. [Gr. +zugos+, _zugos_, a yoke.] A term applied to
some muscles of the face, from their attachment.



INDEX.


A.    PAGE.

  ABDOMEN, 34
  ABSORPTION, 181
    ----, Varieties of, 183
    ----, Cutaneous, 185
  ACETABULUM, 38
  ACIDS, Acetic, 28
    ----, Benzoic, 28
    ----, Muriatic, 440
    ----, Nitric, 440
    ----, Oxalic, 28, 440
    ----, Sulphuric, 440
  AIR, Composition of the, 223
    ----, Influence of, on the Muscles, 90
    ----, Quality of the, 223, 318
    ----, Quantity inhaled, 222
    ----, Quantity exhaled, 228
    ----, Impure Air, the Effects of, 232
  AIR VESICLES, 212
  ALBUMEN, 27
  ANIMAL HEAT, 252
  AORTA, 159
    ----, Valves of the, 157
  APPARATUS, 18
  ARTERIES, Structure of the, 158
    ----, Cutaneous, 285
    ----, Pulmonary, 158
  ATTITUDE, Effects of, on Digestion, 152
    ----, Effects of, on the Voice, 274
    ----, Effects of, in Respiration, 245
  AURICLES of the Heart, 156
  ASPHYXIA, from Drowning, 249
    ----, from Electricity, 250
    ----, from Hanging, 250
    ----, from Carbonic Gas, 251
  AZOTE, 26


B.

  BATHING, Necessity of, 311
    ----, Methods of, 313
    ----, Proper Time for, 316
    ----, Influence of, on the System, 316
    ----, Frequency of, 317
  BEDS, 309
  BILE, 122
  BLOOD, Composition of, 154
    ----, Color of, 204
    ----, Quantity of, 171
    ----, Change of, 225
    ----, Impure, Effects of, 205
  BONES, Anatomy of the, 29
    ----, Physiology of the, 48
    ----, Hygiene of the, 53
    ----, of the Head, 32
    ----, of the Trunk, 34
    ----, of the Upper Extremities, 39
    ----, of the Lower Extremities, 42
    ----, Composition of, 29
    ----, Ossification of, 30
    ----, Union of fractured, 62
    ----, Influence of Position on the, 55
  BRAIN, 329
    ----, Functions of the, 346
    ----, Effects of Impure Blood on the, 360
    ----, Effects of inadequate Mental Exertion, 361
    ----, Effects of excessive Mental Exertion, 363
    ----, Directions for exercising the, 368
    ----, Membranes of the, 334
    ----, Injuries of the, 377
  BRONCHIA, 212
  BRONCHITIS, 214
  BURNS AND SCALDS, 319
  BURSÆ MUCOSÆ, 46


C.

  CÆCUM, 118
  CAPILLARIES, 163
  CARBON, 26
  CARBONIC GAS, where formed, 224
    ----, Effects of, when inhaled, 230
    ----, Effects of, on Combustion, 230
    ----, Effects of, on Respiration, 231
  CARPUS, 41
  CARTILAGE, 45
    ---- of the Larynx, 269
  CAUL, 123
  CELLULAR TISSUE, 19
  CEREBELLUM, 331

  CEREBRUM, 330
  CHEST, 35
    ----, Compression of the, 56
    ----, Influence of the Size of the, 239
  CHILBLAINS, 321
  CHLORINE, 27
  CHYLE, 126
  CHYME, 126
  CIRCULATORY ORGANS, Anatomy, 154
    ----, Physiology of the, 164
    ----, Hygiene of the, 172
  CLAVICLE, 39
  CLOTHING, Kind of, 301
    ----, Amount of, 305
    ----, Cleanliness of, 308
  COCCYX, 38
  COLDS, Treatment of, 248
  COLON, 119
  CONSUMPTION, how frequently produced, 247
  CORNS, Treatment of, 295
  CUTICLE, Structure of the, 282
    ----, Use of the, 293
  CUTIS VERA, Structure of the, 283


D.

  DEFINITIONS, General, 13
  DIAPHRAGM, 73, 215
  DIGESTIVE ORGANS, Anatomy of the, 113
    ----, Physiology of the, 124
    ----, Hygiene of the, 129
    ----, Influence of the Mind on the, 148
    ----, Influence of Pure Air on the, 151
    ----, Influence of Position on the, 152
  DRINKS, how taken, 145
  DROWNED PERSONS, Treatment of, 249
  DUODENUM, 117


E.

  EAR, Bones of, 34, 415
  EPIGLOTTIS, 125, 270
  EXHALANTS, 192
  EXERCISE, how it should be taken, 91
    ----, Influence of, on the Bones, 53
    ----, Influence of, on Muscles, 85
    ----, Influence of, on the Circulation, 173
  EYE, 394
  EXPIRATION, how effected, 220


F.

  FACE, Bones of the, 34
  FASCIA, 66
  FAT, 67, 195
  FEMUR, 42
  FIBRE, 18
  FIBRIN, 27
  FIBULA, 42
  FILAMENT, 18
  FLANNEL, Use of, 302
  FLUIDS, Use of, 17
  FOLLICLE, 192
  FOOD, Quantity of the, 129
    ----, Quality of the, 134
    ----, Manner in which it is taken, 142
    ----, Condition of the system, when taken, 146
  FOOT, Bones of the, 44
  FROZEN LIMBS, Treatment of, 320


G.

  GASTRIC JUICE, 125
  GELATIN, 27
  GLANDS, 193
    ----, Gastric, 116
    ----, Lachrymal, 402
    ----, Lymphatic, 183
    ----, Mesenteric, 121
    ----, Oil, 288
    ----, Perspiratory, 290
    ----, Salivary, 114
  GLOTTIS, 271


H.

  HAIR, 322
  HEART, 154
    ----, Auricles of the, 156
    ----, Ventricles of the, 156
  HEAT, Animal, 252
    ----, Hygiene of, 261
  HEARING, Anatomy of the Organs of, 414
    ----, Physiology of the Organs of, 420
    ----, Hygiene of the Organs of, 422
  HUMERUS, 39
  HEMORRHAGE, Means of arresting, 175
  HYDROGEN, 26


I.

  ILEUM, 118
  INTESTINES, 117
  INNOMINATUM, 37

  INSPIRATION, how effected, 219
  IRON, 25


J.

  JEJUNUM, 118
  JOINTS, Structure of the, 45


L.

  LACTEALS, 120, 181
  LAMINÆ, 17
  LARYNX, 268
  LARYNGITIS, 276
  LIGAMENTS, 23, 47
    ----, Use of, 50
    ----, Capsular, 40
  LIGHT, Influence on the Skin, 318
  LIME, 25
  LIVER, 122
  LUNGS, 209
  LYMPH, 30
  LYMPHATICS, Anatomy of the, 181
    ----, Physiology of the, 183
    ----, Hygiene of the, 188
    ----, Cutaneous, 287


M.

  MAGNESIA, 25
  MARROW, Uses of, 24

  MEDIASTINUM, 211
  MEDULLA OBLONGATA, 333
  MEMBRANE, 19
    ----, Adipose, 20
    ----, Cellular, 19
    ----, Dermoid, 22, 282
    ----, Mucous, 21
    ----, Muscular, 24
    ----, Serous, 21
  MESENTERY, 120
  METACARPUS, 41
  MOUTH, Structure of, 113
  MUCUS, 28
  MUSCLES, Anatomy of, 64
    ----, Physiology of, 76
    ----, Hygiene of, 85
    ----, Compression of, 93, 276
    ----, Exhaustion of, 87, 101
    ----, Effects of Pure Blood on, 89
    ----, Effects of Pure Air on the, 90
    ----, Effects of Light on the, 90
    ----, Influence of the Mind on, 93
    ----, Influence of Position on, 90
    ----, Intercostal, 216
    ----, Respiratory, 216


N.

  NAILS, 324
  NERVES, Cranial, 335, 350
    ----, Cutaneous, 286
    ----, Respiratory, 340, 352
    ----, Spinal, 341, 351
    ----, Sympathetic, 343, 356
  NERVOUS SYSTEM, Anatomy of, 327
    ----, Physiology of, 346
    ----, Hygiene of, 358
  NITROGEN, 26
  NOSE, Structure, 389
  NURSES, Directions for, 433
  NUTRITION, 200
    ----, Hygiene of, 205


O.

  OESOPHAGUS, 116
  OIL-GLANDS, Structure of the, 288
    ----, Use of the, 297
  OMENTUM, 123
  ORGAN, 18
  ORGANIC AND INORGANIC BODIES, Difference between, 14
  ORIFICE, Cardiac, 116
    ----, Pyloric, 116
  OSMAZOME, 28
  OXYGEN, 26
    ----, Quantity at each Inspiration, 222


P.

  PAPILLA, 284
  PANCREAS, 122
  PAROTID GLAND, 114
  PATELLA, 42
  PERICARDIUM, 155
  PERICHONDRIUM, 31
  PERICRANIUM, 31
  PERIOSTEUM, 31
  PELVIS, Bones of the, 37
  PERSPIRATORY APPARATUS, 290
    ---- Use of, 298
  PHALANGES, 42, 45
  PHARYNX, 115
  PHOSPHORUS, 26
  PLEURA, 211
  POISONS, and their Antidotes, 439

  POTASH, 25
  PRESERVATION OF HEALTH, 425


R.

  RADIUS, 41
  READING, Proper Position in, 275
  RECTUM, 120
  REMOVAL OF DISEASE, 426
  RESPIRATORY ORGANS, Anatomy of, 209
    ----, Physiology of, 217
    ----, Hygiene of, 228
  RETINA, 397
  RIBS, 35
  ROOMS, Ventilation of, 233
    ----, Warming of, 238


S.

  SACRUM, 38
  SALIVA, Its Use, 124
  SCAPULA, 39
  SECRETORY ORGANS, Anatomy of, 192
    ----, Physiology of, 193
    ----, Hygiene of, 197
  SENSES, 378
  SICK-ROOM, Ventilation of, 236
  SITTING, Proper Position in, 99
  SKELETON, 29
  SKIN, Anatomy of the, 282
    ----, Physiology of the, 293
    ----, Hygiene of the, 301
  SKULL, Structure of, 32
  SLEEP, Necessity of, 92
  SLEEPING-ROOMS, Ventilation of, 235
  SMELL, Anatomy of the Organs of, 389
    ----, Physiology of the Organs of, 391
  SODA, 25
  SOLIDS, Arrangement of, 17
  SOUND, 273
  SPINAL COLUMN, Structure of, 36
    ----, Curvature of, 57, 60
  SPINAL CORD, 36, 340
  SPLEEN, 123
  SPRAINS, 63
  STAMMERING, how improved, 281
  STERNUM, 35
  STOMACH, 116
  SUBLINGUAL GLAND, 115
  SUBMAXILLARY GLAND, 115
  SULPHUR, 26
  SUTURES, 33
  SYNOVIAL MEMBRANE, 46
  SYNOVIA, 49
  SYSTEM, 18


T.

  TARSUS, 42
  TASTE, Anatomy of the Organs of, 384
    ----, Physiology of the Organs of, 386
  TEETH, Anatomy of the, 105
    ----, Physiology of the, 109
    ----, Hygiene of the, 110
  TENDONS, 23, 65
  THORACIC DUCT, 120
  THORAX, 35
  THROAT, Extraneous Bodies in, 281
  TIBIA, 42
  TISSUE, 18
    ----, Adipose, 20
    ----, Cartilaginous, 23
    ----, Fibrous, 22
    ----, Osseous, 23
    ----, Nervous, 24
  TOUCH, Sense of, 378
    ----, Hygiene of the, 379
  TRACHEA, 212


U.

  ULNA, 40
  UVEA, 396


V.

  VALVES of the Heart, 157
    ----, Use of the, 164
    ----, of the Veins, 162
  VEINS, 160
    ----, Cutaneous, 285
  VENTILATION, 233
  VENTRICLES of the Heart, 156
  VERTEBRA, 36
  VISION, Anatomy of the Organs of, 394
    ----, Physiology of the Organs of, 404
    ----, Hygiene of the Organs of, 410
  VOCAL ORGANS, Anatomy of the, 268
    ----, Physiology of the, 272
    ----, Hygiene of the, 274
  VOCAL CORDS, 270


W.

  WATCHERS, Directions for, 136
  WOUNDS, Treatment of, 178
  WRITING, Proper Position when, 103



KEY TO ANATOMICAL OUTLINE PLATES.


SUGGESTIONS TO TEACHERS.

In using these plates, we would suggest, that the pupil carefully
examine the illustrating cuts interspersed with the text, in
connection with the lesson to be recited. The similarity between these
and the plates will enable the pupil to recite, and the teacher to
conduct his recitation, from the latter.

Let a pupil show the situation of an organ, or part, on an anatomical
outline plate, and also give its structure; while other members of the
class note all omissions and misstatements. Another pupil may give the
use of that organ, and if necessary, others may give an extended
explanation. The third may explain the laws on which the health of the
part depends, while other members of the class supply what has been
omitted. After thus presenting the subject in the form Of topics,
questions may be proposed promiscuously, from each paragraph, and
where examples occur in the text, let other analogous ones be given.

If the physiology and hygiene of a given subject have not been
studied, confine the recitation to those parts only on which the pupil
is prepared. When practicable, the three departments should be united;
but this can only be done when the chapter on the hygiene has been
learned, while the physiology can be united with the anatomy, in all
chapters upon physiology.


PLATE I.

A FRONT VIEW OF THE SKELETON.

_Bones of the Head._ 7, The sphenoid bone. 8, The frontal bone. 10,
The parietal bone. 11, The os unguis. 12, The superior maxillary bone,
(upper jaw.) 13, The nasal bone. 14, The ethmoid bone. 15, The malar
bone, (cheek-bone.) 16, The vomer. 17, The inferior maxillary bone,
(the lower jaw.) _a_, Its body. _b_, Its ramus, or branch. 18, The
teeth.

_Bones of the Trunk._ 1, 1, The spinal column. 2, The sternum. 3, 3,
The ribs. 4, The sacrum. 5, The innominatum.

_Bones of the Upper Extremities._ 19, The clavicle, (collar-bone.) 20,
The scapula, (shoulder blade.) 21, The humerus. 22, The ulna. 23, The
radius. 24, 25, 26, 27, 28, 29, 30, 31, The bones of the carpus
(wrist.) 32, 32, 32, The five bones of the metacarpus, (the palm of
the hand.) 33, 33, 33, The first range of finger-bones. 34, 34, The
second range of finger-bones. 35, 35, 35, The third range of
finger-bones.

_Bones of the Lower Extremities._ 36, The femur, (thigh-bone.) 37, The
patella, (knee-pan.) 38, The tibia, (shin-bone.) 39, The fibula. 40,
40, 40, The bones of the tarsus, (instep.) 41, 41, The bones of the
metatarsus, (middle of the foot.) 42, 42, The bones of the toes.


ARTICULATIONS. (Left side of the plate.)

_Ligaments of the Trunk._ 1, 1, The common spinal ligament. 2, 2, The
intervertebral ligament, (cartilage between the vertebrae.) 9, 10, 11,
12, Articulations of the ribs with the spinal column. 13, 13, 14, 15,
16, Ligaments that connect the cartilages of the ribs with the
sternum.

_Ligaments of the Upper Extremities._ 25, The ligament that connects
the clavicle and sternum. 27, The ligament that connects the upper rib
and clavicle. 28, 29, 30, Ligaments that connect the clavicle and
scapula. 31, 32, 33, 34, Ligaments of the shoulder-joint. 35, 35, 36,
Ligaments of the elbow-joint. 37, 38, 39, 40, Ligaments of the wrist.
41, 42, 43, 44, Ligaments of the fingers.

_Ligaments of the Lower Extremities._ 49, 49, Ligaments of the
hip-joint. 50, 50, Ligaments of the patella. 51, 52, 53, 54, 55,
Ligaments of the knee-joint. 56, A large bursa mucosa. 57, The
ligament of the tibia and fibula. 58, 58, The interosseous ligament.
59, 59, Ligaments of the ankle-joint 60, 61, 62, Ligaments of the
metatarsus. 63, 64, Ligaments of the toes.

A, The brachial artery. B, The brachial vein. C, The radial artery D,
The femoral artery. E, The femoral vein. F, G, The anterior tibia
artery.


PLATE II.

A BACK VIEW OF THE SKELETON.

_Bones of the Head._ 5, The occipital bone. 6, The parietal bone. 7,
The temporal bone. 8, The frontal bone. 9, The sphenoid bone. 15, The
malar bone. 16, The nasal bone. 17, The superior maxillary bone,
(upper jaw.) 18, The inferior maxillary bone, (lower jaw.) 19, The
teeth.

_Bones of the Trunk._ 1, 1, The spinal column. 2, The sacrum. 3, The
coccyx. 20, The innominatum. 4, 4, The ribs.

_Bones of the Upper Extremities._ 21, The clavicle, (collar-bone.) 22,
The scapula, (shoulder-blade.) 23, The humerus. 24. The ulna, 25, The
radius. 26, 27, 28, 29, 30, 31, 32, The bones of the carpus, (wrist.)
33, 33, 33, The bones of the metacarpus, (palm of the hand.) 34, 34,
34, The first range of finger-bones. 35, 35, The second range of
finger-bones. 36, 36, 36, The third range of finger-bones.

_Bones of the Lower Extremities._ 37, The femur, (thigh-bone.) 38, The
patella, (knee-pan.) 39, The tibia, (shin-bone.) 40, The fibula. 41,
42, 43, 44, 45, The bones of the tarsus, (instep.) 46, 46, The bones
of the metatarsus, (middle of the foot.) 47, 47, Bones of the toes.


ARTICULATIONS. (Left side of the plate.)

_Ligaments of the Trunk._ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, Ligaments of
the spinal column. 14, 14, 15, 15, Ligaments that connect the ribs and
spinal column. 11, 11, 21, 22, 23, 24, 25, 26, Ligaments that connect
the sacrum and innominatum.

_Ligaments of the Upper Extremities._ 27, 28, Ligaments that
connect the clavicle and scapula. 29, The capsular ligament of the
shoulder-joint. 30, 30, Ligaments of the elbow. 31, 32, 33, 34,
Ligaments of the carpus, (wrist.)

_Ligaments of the Lower Extremities._ 9, Tendon of the gluteus muscle.
35, The capsular ligament of the hip-joint. 36, 36, Ligaments of the
knee-joint. 37, The ligament that connects the tibia and fibula. 38,
The interosseous ligament. 39, 40, Ligaments of the ankle-joint.


PLATE III.

A FRONT VIEW OF THE MUSCLES.

_Muscles of the Head and Neck._ 7, The sterno-mastoideus muscle. 8,
The sterno-hyoideus muscle. 9, The omo-hyoideus muscle. 10, The
trapezius muscle. 11, The orbicularis oculi muscle. 12, The frontal
muscle. 14, The orbicularis oris muscle. 15, The elevator muscle of
the nostrils. 16, The zygomatic muscle. 17, The depressor of the lower
lip. 18, The depressor anguli oris muscle. 19, The triangular muscle
of the nose. 20, 21, The aural muscles. 22, The masseter muscle.

_Muscles of the Trunk._ 2, 3, The external oblique muscles.

_Muscles of the Upper Extremities._ 1, The grand pectoral muscle. 3,
4, The serratus muscle. 23, The deltoid muscle. 24, The biceps
brachialis muscle. 25, The coraco-brachialis muscle. 26, The anterior
brachial muscle. 27, The triceps brachialis muscle. 28, The long
supinator muscle. 29, The external radial muscle. 30, The pronator
teres muscle. 31, The anterior radial muscle. 32, The palmaris brevis
muscle. 33, The anterior ulnar muscle. 35, The palmar muscle. 36, The
abductor muscle of the thumb. 37, The adductor muscle of the thumb.
38, 39, Small flexor muscles of the thumb. 40, The abductor muscle of
the little finger. 41, 41, The lumbricales muscles. 61, 61, The
bifurcation of the tendons of the superficial flexor muscle, in the
fingers.

_Muscles of the Lower Extremities._ 42, The fascia lata muscle. 43,
The sartorius muscle. 44, The rectus femoris muscle. 45, The vastus
externus muscle. 46, The vastus internus muscle. 47, The internal
straight muscle. 48. The pectineus muscle. 49, The adductor muscle.
50, The psoas muscle. 51, The tibialis anticus muscle. 52, The long
extensor muscle of the great toe. 53, The long extensor muscle of the
toes. 54, The anterior peroneal muscle. 55, The long lateral peroneal
muscle. 56, 57, The gastrocnemii muscles. 58, The long flexor muscle
of the great toe. 69, The short extensor muscles of the toes. 60, The
abductor muscle of the great toe.

The figures and letters on the left side of the plate, indicate the
position of important fasciæ, that cover the muscles and enclose the
tendons.


PLATE IV.

BACK VIEW OF THE MUSCLES.

_Muscles of the Head and Neck._ 4, The sterno-mastoideus muscle. 5,
The complexus muscle. 6, The mylo-hyoideus muscle. 7, 8, The
occipito-frontalis muscle. 9, The masseter muscle. 10, 11, 12, The
anterior, middle, and posterior aural muscles. 13, The temporal
muscle.

_Muscles of the Trunk._ 1, 1, The trapezius muscle. 2, The latissimus
dorsi muscle. 3, The rhomboideus muscle. 4, The external oblique
muscle.

_Muscles of the Upper Extremities._ 5, The deltoid muscle. 6, 7, The
infra-spinatus muscle. 9, The triceps extensor muscle. 10, The
internal brachial muscle. 11, The long supinator muscle. 12, The
external radial muscle. 13, The second external radial muscle. 14, The
anconeus muscle. 15, 16, The extensor digitorum communis muscle. 17,
The extensor carpi ulnaris muscle. 18, The flexor carpi ulnaris. 19,
20, The extensor ossis metacarpi pollicis muscles. 21, An extensor
muscle of the thumb. 22, 28, Interossii muscles.

_Muscles of the Lower Extremities._ 29, The gluteus maximus muscle.
30, The gluteus medius muscle. 31, The biceps flexor cruris muscle.
32, The semi-tendinosus muscle. 33, The semi-membranosis muscle. 34,
The gracilis muscle. 35, The adductor muscle. 36, The vastus externus
muscle. 37, The sartorius muscle. 38, 39, The gastrocnemii muscles.
40, The long peroneal muscle. 41, The external peroneal muscle. 42,
The long flexor muscle of the great toe. 43, The long extensor muscle
of the toes. 44, The short extensor muscle of the toes. 47, The short
flexor muscle of the toes.

The figures and letters on the left side of the plate, indicate the
position of membranous fasciæ which envelop the muscles and tendons.


PLATE V.

ORGANS OF THE THORAX AND ABDOMEN.

Fig. 1. _The Mouth and Neck._ (A Side view.) 1, The upper lip. 2, The
lower lip. 3, The upper jaw. 4, The lower jaw. 5, The tongue. 6, The
hard palate, (roof of the mouth.) 7, The parotid gland. 8, The
sublingual gland. T, The larynx. 10, The pharynx. 11, The oesophagus.
12, The upper portion of the spinal column. C, The spinal cord.

_The Chest and its Organs._ 9, 9, The trachea. R, The right auricle of
the heart. L, The left auricle. 13, The left ventricle of the heart.
14, The right ventricle. 15, The aorta. 16, The pulmonary artery. 17,
The vena cava descendens. 18, The right subclavian vein. 19, The left
subclavian vein. 20, The right jugular vein. 21, The left jugular
vein. 22, The right carotid artery. 23, The left carotid artery. 24,
25, 26, The upper, middle, and lower lobes of the right lung. 27, 28,
The upper and lower lobes of the left lung. 29, 29, 29, The diaphragm.
P, P, P, P, The pleura, that lines the cavity of the chest. S, S, The
clavicles. O, O, O, O, The ribs. M, M, M, M, Muscles of the chest. 40,
The thoracic duct, opening into the left subclavian vein.

_The Abdomen and its Organs._ 30, The stomach. 31, 32, The right and
left lobe of the liver. F, The fissure that separates the two lobes.
33, The gall bladder. 34, 34, The duodenum. 35, The ascending colon.
36, The transverse colon. 37, The descending colon. 38, 38, 38, 38,
The small intestine. 39, 39, The walls of the abdominal cavity turned
down. 41, The spleen.

Fig. 2. _The Relation of the Lacteals and Thoracic Duct._ 1, 1, A
section of the small intestine. 2, 2, 2, 2, 2, 2, 2, 2, Mesenteric
glands, through which the lacteals from the intestine pass. 3, Several
lacteal vessels entering the enlarged portion and commencement of the
thoracic duct. 5, 5, 5, The thoracic duct. 6, The thoracic duct
opening into the left subclavian vein. 7, (See 40, Fig. 1.) 8, The
right subclavian vein. 9, The vena cava descendens. 10, 11, 11, The
aorta. 12, The carotid arteries. 13, 13, The jugular veins. 14, The
vena azagos. 15, 15, The spinal column. 16, The diaphragm.

Fig. 3. _The Relation of the Larynx, Trachea, Bronchia, and
Air-cells._ 1, 1, 1, An outline of the right lung. 2, 2, 2, An outline
of the left lung. 3, The larynx. 4, The trachea. 5, The right
bronchia. 6, The left bronchia. 7, 7, 7, 7, Divisions of the right
bronchia. 8, 8, 8, 8, Divisions of the left bronchia. 9, 9, 9, 9, 9,
9, Air-cells.

Fig. 4. _An ideal View of a lateral and vertical Section of the
Larynx._ 1, 1, The superior vocal cords, (ligaments.) 2, 2, The
inferior vocal cords. 3, 3, The glottis. 4, 4, The ventricles of the
larynx.


PLATE VI.

HEART, ARTERIES, AND VEINS

Fig. 1. _The Heart and large Arteries._ 1, The right auricle of the
heart. 2, The right ventricle of the heart. 3, The left auricle. 4,
The left ventricle. 5, The pulmonary artery. 6, The aorta. 7, 7, The
descending aorta. 8, The arteria innominata. 9, The left carotid
artery. 10, The left subclavian artery. 56, The right subclavian
artery.

_Arteries of the Neck and Head._ 15, The right carotid artery. 16, The
left carotid artery. 17, The right temporal artery. 50, The right
facial artery. 54, The left temporal artery.

_Arteries of the Upper Extremities._ 11, 11, The left brachial artery.
12, The left radial artery. 13, 13, The right brachial artery. 14, The
right radial artery. 51, The right ulnar artery.

_Arteries of the Lower Extremities._ 18, The left iliac artery. 19,
The right iliac artery. 20, The left femoral artery. 21, The right
femoral artery. 22, The peroneal artery. 23, The left anterior tibial
artery. 24, The muscular artery. 25, 25, The right and left arteria
profunda. 26, The right anterior tibial artery. 27, The right peroneal
artery.

_The Veins of the Neck and Head._ 28, The vena cava descendens. 29,
The left subclavian vein. 30, The right subclavian vein. 31, The right
jugular vein. 32, The left jugular vein. 53, The right temporal vein.
55, The left temporal vein. 49, The right facial vein.

_Veins of the Upper Extremities._ 33, The left brachial vein. 34, The
left radial vein. 35, The right brachial vein. 36, The right radial
vein. 51, The right ulnar vein.

_Veins of the Lower Extremities._ 37, The vena cava ascendens. 38, The
left iliac vein. 39. The right iliac vein. 40, The left femoral vein.
41, The right femoral vein. 42, The left anterior tibial vein. 43, The
left peroneal vein. 44, The right anterior tibial vein. 45, The right
peroneal vein. 46, 46, The profunda veins. 47, The muscular veins. 48,
48, 48, 48, 48, 48, Intercostal arteries and veins.

Fig. 2. _The Relation of the Cavities of the Heart to the large
Blood-vessels._ 1, The vena cava descendens. 2, The vena cava
ascendens. 3, The right auricle of the heart. 4, The opening between
the right auricle and right ventricle. 5, The right ventricle. 6, The
tricuspid valves. 7, The pulmonary artery. 8, 8, The branches of the
pulmonary artery that pass to the right and left lung. 9, The
semilunar valves of the pulmonary artery. 10, The left pulmonary
veins. 11, The right pulmonary veins. 12, The left auricle. 13, The
opening between the left auricle and left ventricle. 14, The left
ventricle. 15, The mitral valves. 16, 16, The aorta. 17, The semilunar
valves of the aorta. 18, The septum between the right and left
ventricle.

Fig. 3. _An ideal View of the Heart, Arteries, and Veins._ A, The
right auricle. B, The right ventricle. C, The tricuspid valves. D, The
opening between the right auricle and right ventricle. E, The left
auricle. F, the left ventricle. G, The mitral valves. H, The opening
between the left auricle and left ventricle. I, The septum between the
right and left ventricle. K, The pulmonary artery. L, The semilunar
valves of the pulmonary artery. M, M, The right pulmonary artery. N,
N, The left pulmonary artery. O, O, O, O, O, O, The capillary vessels
of the lungs. P, P, P, The right pulmonary vein. Q, Q, The left
pulmonary vein. R, R, The aorta. S, The semilunar valves of the aorta.
T, T, A branch of the aorta to the upper extremities. U, U, U, U, A
branch to the lower extremities. V, V, V, V, V, V, The capillary
vessels at the extremity of the branches of the aorta. W, W, The
descending vena cava. X, X, X, The ascending vena cava.

In Figs. 1, 2, 3, the course of the blood through the circulatory
vessels is indicated by arrows.


PLATE VII.

THE PULMONARY CIRCULATION.

Fig. 1. 1, The right auricle of the heart. 2, The left auricle. 3, The
right ventricle of the heart. 4, The left ventricle. 5, The pulmonary
artery. 6, The branch of the pulmonary artery to the left lung. 7, The
branch of the pulmonary artery to the right lung. 8, 8, 8, 8, 8, 8, 8,
8, 8, 8, Branches of the pulmonary artery in the right and left lung.
9, 9, 9, 9, 9, 9, Air-cells. 10, 10, 10, 10, 10, 10, 10, Small
pulmonary veins in the right and left lung. 11, The left pulmonary
vein. 12, 12, The right pulmonary vein.

Fig. 2. _An ideal View of the Pulmonary Circulation._ 1, 1, The right
lung. 2, 2, The left lung. 3, The trachea. 4, 4, 4, 4, 4, The right
bronchia. 5, 5, 5, 5, 5, The left bronchia. 6, 6, 6, 6, 6, 6,
Air-cells, with arteries and veins passing around them. 7, The right
auricle of the heart. 8, The right ventricle of the heart. 9, The
tricuspid valves. 10, The pulmonary artery. 11, 11, 11, 11, The right
pulmonary artery. 12, 12, 12, 12, 12, The left pulmonary artery. 13,
13, 13, 13, The right pulmonary vein. 14, 14, 14, 14, The left
pulmonary vein. 15, The left auricle. 16, The left ventricle. 17, The
mitral valves. 18, The septum between the right and left ventricles.

Fig. 3. _An ideal View of the Capillaries._ 1, 1, A branch of the
pulmonary artery. 2, 2, A branch of the pulmonary vein. 3, 3,
Capillary vessels between the artery and vein.

Fig. 4. _An ideal View of the Relations of the Bronchia, Air-cells,
Pulmonary Arteries, and Veins._ 1, A bronchial tube. 2, 2, 2,
Air-cells. 3, A branch of the pulmonary artery. 4, A branch of the
pulmonary vein.


PLATE VIII.

THE CEREBRUM, CEREBELLUM, SPINAL CORD, AND NERVES

1, The cerebrum. 2, The cerebellum. 3, 3, The spinal cord. 4, The
brachial plexus of nerves. 5, The lumbar plexus of nerves. 6, The
sacral plexus of nerves. 7, The facial nerve. 8, 17, The radial nerve.
9, 9, 16, The ulnar nerve. 10, The median nerve. G, The circumvex
nerve of the shoulder.

11, 11, The great sciatic nerve. 12, The external popliteal, or
peroneal nerve. 13, 13, The posterior tibial nerve. 14, The external
tibial nerve. 15, The muscular branch of the external peroneal nerve.
18, The muscular branch of the sciatic nerve. P, Q, The posterior
tibial nerve.

The letters and other figures indicate minor nervous filaments
distributed to the various muscles and the skin.


PLATE IX.

THE SKIN.

Fig. 1. _A perspiratory Tube and Gland._ 1, 1, The contorted portion
of the tube that forms the gland. 2, 2, Two branches which unite to
form the main duct of the gland. 3, 3, The perspiratory tube. 4, The
cuticle. 5. Its colored portion. 6, The cutis vera, (true skin.) 7, 7,
Fat vesicles, in which the gland is imbedded.

Fig. 2. _A Papilla of the Skin._ 1, 1, Two papillæ, formed of an
artery vein, and nerve. 2, 2, 2, 2, Nerves forming a loop in the
papillæ. 3, 3, Arteries of the papillæ. 4, 4, Veins of the papillæ. 5,
5, A net-work of arteries, veins, and nerves. 6, 6, Nerves of the
skin. 8, 8, Arteries of the skin. 7, 7, Veins of the skin.

Fig. 3. _A Hair, and its Oil-Glands._ 1, 1, The hair. 2, 2, The sheath
of the hair. 3, Oil-glands that surround the bulb of the hair, the
ducts of which open into the sheath of the hair, (2, 2.)

Fig. 4. _A Section of the Skin._ 1, 1, The cuticle. 2, 2, Its colored
portion. 3, 3, The papillary layer. 4, 4, A net-work of arteries,
veins, and nerves, upon the upper surface of the cutis vera. 5, 5, 5,
5, The cutis vera, (true skin.) 6, 6, 6, Hairs that originate in the
cutis vera. 7, 7, 7, Oil-glands, the ducts of which connect with the
sheath of the hair. 8, 8, 8, 8, 8, 8, 8, 8, Perspiratory glands and
their ducts. 9, 9, 9, 9, 9, Nerves of the skin 10, 10, 10, 10, 10,
Arteries of the skin. 11, 11, 11, 11, 11, Veins of the skin. 12, 12,
12, 12, Papillæ, or ridges of the skin.


PLATE X.

AN ANTERO-POSTERIOR SECTION OF THE EYE.

Fig. 1. 1, 1, The sclerotic coat. 2, 2, The cornea. 3, 3, The choroid
coat. 4, 4, The retina. 5, 5, The iris. 6, 6, The posterior chamber of
the eye that contains the aqueous humor. 7, 7, The anterior chamber.
8, 8, The pupil. 9, The crystalline humor. 10, 10, The vitreous humor
11, The optic nerve. 12, A representation of a pen. 13, An inverted
image of the pen (12) on the retina. 14, 14, A canal surrounding the
crystalline humor. 15, 15, The bevelled junction of the cornea and
sclerotic coats. A, a perpendicular ray of light from the pen. B, B,
oblique rays, that are refracted in passing through the humors of the
eye.

Fig. 2. _A View of the External, Middle, and Internal Ear._ 1, 1, The
external ear. 2, The meatus auditorius externus, (the tube that
connects with the middle ear.) 3. The membrana tympani, (drum of the
ear.) 8, 8, The tympanum, (middle ear.) 4, The malleus. 5, The incus.
6, The orbicularis. 7, The stapes, (stirrup-bone,) that connects with
the vestibule of the internal ear. 9, 9, (4, 5, 6, 7, The small bones
of the middle ear,) 10, 11, 12, The semicircular canals. 13, 13, The
cochlea. 14, The auditory nerve. 15, The division of the auditory
nerve to the semicircular canals. 16, The division to the cochlea. 17,
17, The Eustachian tube. 18, The chorda tympani nerve. 19, The seventh
pair (facial) nerve. 20, The styloid process of the temporal bone. 21,
21, 21, 21, 21, The petrous or hard portion of the temporal bone, in
which the parts of the middle and internal ear are situated.


       *       *       *       *       *
           *       *       *       *
       *       *       *       *       *


Below is given the Title of a Book on a new plan, just published,
intended for beginners in the study of Physiology.


       *       *       *       *       *


HUMAN AND COMPARATIVE

ANATOMY,

PHYSIOLOGY, AND HYGIENE


BY

MRS. EUNICE P. CUTTER.


WITH ONE HUNDRED ENGRAVINGS.


NEW YORK:

CLARK, AUSTIN, AND SMITH

3 PARK ROW



TEXT BOOKS

UPON

=Anatomy, Physiology, and Hygiene.=

Recommended by the Hon. N. W. EDWARDS, School Sup't, Ill.


HUMAN AND COMPARATIVE ANATOMY, PHYSIOLOGY, AND HYGIENE. For District
Schools. With 100 Engravings. 132 pages. By MRS. EUNICE P. CUTTER.
Price 33 cts.

This work contains full directions for the _study_ and _teaching_
of Anatomy, Physiology, and Hygiene. This is a new feature. _Every
teacher would profit by it._ The plan of the work can be gathered from
the following _fac-simile_ of the table of contents:--

[Illustration: Fac-simile of the table of contents]



                  *       *       *       *       *



Transcriber's note:


Typographical problems have been changed and are listed below.

Author's archaic and variable spelling is mostly preserved.

Author's punctuation style is mostly preserved.

Passages in italics indicated by _underscores_.

Passages in bold indicated by =equal signs=.

In paragraph 97, '[s]' is used to represent the integral symbol.

Greek words and letters have been transliterated and placed between
+marks+.

This transcription is faithful to the original transliterations of
Greek (which occur in italics), even when they seem incorrect.

Author's Greek transliterations included vowels with macrons. These
macrons have been changed to circumflexes in order to display
correctly in this text transcription.

The original revision questions at the bottom of each page have been
set between lines that look like '-=-=-=-=-=-=-=-=-=-=-=-='.

Footnotes have been placed directly below their relevant paragraphs.


Transcriber's changes:

  Title page: Was 'DESIGNER' (=DESIGNED= FOR)

  Title page: Was 'Massachuetts' (In the Clerk's Office of the
              District Court of the District of =Massachusetts=.)

  Title page: Added '.' (No. 15 Vandewater Street, N. =Y.=)

  Page 18: Added ',' (_Example._ The digestive apparatus consists of
           the =teeth,= stomach, liver, &c., all of which aid in the
           digestion of food.)

  Page 23, Fig. 5: Added '.' (=Fig.= 5. A section of the femur,
           (thigh-bone.) 1, 1, The extremities, showing a thin plate
           of compact texture)

  Page 24: Was 'serious' (40. How does the mucous differ from the
           =serous= tissue? What is the appearance of the external
           surface of this membrane?)

  Page 27: Added comma (The most important compounds are _Al-bu´men_,
           =_Fi´brin_,= _Gel´a-tin_)

  Page 27: Was 'organ ized (57. What are proximate elements? Do they
           exist already formed in =organized= bodies? Name the most
           important compounds.)

  Page 29: Added '.' (The earthy portion of the bones gives them
           solidity and strength, while the animal part endows them
           with =vitality.=)

  Page 33, Fig. 7: Added '.' (=7.= 1, 1, The coronal suture at the
           front and upper part of the skull, or)

  Page 33, Fig. 7: Was 'cra nium' over line break. (suture at the
           front and upper part of the skull, or =cranium=. 2, The
           sagittal suture on the top of the skull.)

  Page 35, Fig. 9: Added '.' (=Fig.= 9. 1, The first bone of the
           sternum, (breast-bone.) 2. The second bone of the
           sternum.)

  Page 36: Added '.' (83. Describe the thorax. Explain fig. 9. 84.
           Describe the =sternum.= 85. Describe the ribs.)

  Page 36: Added '?' (88. Give the structure of the vertebra. Where is
           the spinal cord placed? 89. What is placed between each
           =vertebra?= What is its use?)

  Page 37, Fig 10: Added '.' (5, The transverse =process.= 7, The
           inferior articulating process.)

  Page 38, Fig 12: Added '.' (2, The sacrum. 3, The =coccyx.= 4, 4,
           The acetabulum. a, a, The pubic portion)

  Page 38: Added '.' (In the adult? Describe the acetabulum. 93.
           Describe the =sacrum.= Explain fig. 12. 94. Describe the
           coccyx.)

  Page 41: Was 'out side' over page break (101. The RADIUS articulates
           with the bones of the carpus and forms the wrist-joint.
           This bone is situated on the =outside= of the fore-arm)

  Page 41, Fig. 16: Added '.' (11, 11, First range of finger-bones.
           12, 12, Second range of finger-bones. 13, 13, Third range
           of =finger-bones.= 14, 15, Bones of the thumb.)

  Page 42: Was 'meta carpal' over line break. (and upon the other, the
           first bone of the thumb. The five =metacarpal= bones
           articulate with the second range of carpal bones.)

  Page 42: Added '.' (101. The radius. 102. How many bones in the
           carpus? How are they ranged? =103.= Describe the)

  Page 42: Added '.' (103. Describe the =metacarpus.=)

  Page 42: Was 'sim ilar' over line break. (109. The FIBULA is a
           smaller bone than the tibia, but of =similar= shape. It is
           firmly bound to the tibia, at each extremity.)

  Page 43, Fig. 17: Added '.' (=Fig.= 17. 1, The shaft of the femur,
           (thigh-bone.))

  Page 44: Was 'a' (They articulate at one extremity with one range of
           tarsal bones; =at= the other extremity, with the first
           range of the toe-bones.)

  Page 45, Fig. 21: Added '.' (Fig. 21 The relative position of the
           bones, cartilages, and synovial =membrane.= 1, 1, The
           extremities of two bones that concur to form a joint.)

  Page 46: Added '.' (112. Describe the phalanges. 113-118. _Give the
           anatomy of the =joints.=_ 113. What is said of the joints?
           Of what are the joints composed?)

  Page 46: Added '?' (112. Describe the phalanges. 113-118. _Give the
           anatomy of the joints._ 113. What is said of the joints? Of
           what are the joints =composed?=)

  Page 52, Fig. 28: Added '.' (14, The hand. 15, The haunch-bone. 16,
           The =sacrum.= 17, The hip-joint.)

  Page 52, Fig. 28: Added '.' (19, The patella. 20, The =knee-joint.=
           21, The fibula. 22, The tibia.)

  Page 65: Added '.' (150-160. _Give the anatomy of the =muscles.=_
           150. What is said of the muscles? 151. Give their
           structure.)

  Page 70, Fig. 39: Added '.' (Fig. =39.= A front view of the muscles
           of the trunk.)

  Page 70, Fig. 39: Was 'superficia' (On the left side the
           =superficial= layer is seen; on the right, the deep layer.
           1, The pectoralis major muscle.)

  Page 72, Fig. 41: Added '.' (Fig. 41 The first, second, and part of
           the third layer of muscles of the =back.= The first layer
           is shown on the right, and the second on the left side.)

  Page 72, Fig. 41: Added '.' (_Practical Explanation._ The muscles 1,
           11, 12, draw the scapula back toward the =spine.= The
           muscles 11, 12, draw the scapula upward toward the head)

  Page 73, Fig. 42: Added '.' (Fig. 42. A representation of the under,
           or abdominal side of the =diaphragm.= 1, 2, 3, 4, The
           portion which is attached to the margin of the ribs.)

  Page 74, Fig. 43: Added '.' (=Fig.= 43. A front view of the
           superficial layer of muscles of the fore-arm. 5, The flexor
           carpi radialis muscle.)

  Page 74: Added '.' (That perform the delicate movements of the
           fingers? Give the use of some of the muscles represented by
           =fig.= 43. Those represented by fig. 44.)

  Page 81: Added '.' (The ball and socket joints, as the shoulder, are
           not limited to mere flexion and =extension.= No joint in
           the system has the range of movement that is)

  Page 84, Fig. 47: Added '.' (The muscles 9, fig. 46, and 6, =fig.=
           47, bend the neck forward. The muscles 3, 4, fig. 47,
           elevate the head and chin.)

  Page 84, Fig. 47: Added '.' (The muscles 26, 27, 28, fig. 46, bend
           the lower limbs on the body, at the =hip.= The muscle 28,
           fig. 46, draws one leg over the other)

  Page 84, Fig. 47: Added '.' (The muscles 27, 28, =fig.= 47, extend
           the lower limbs on the body, at the hip. The muscles 29,
           30, 31, fig. 46, extend the leg at the knee.)

  Page 84, Fig. 47: Added ',' (The muscles 27, 28, fig. =47,= extend
           the lower limbs on the body, at the hip. The muscles 29,
           30, 31, fig. 46, extend the leg at the knee.)

  Page 84, Fig. 47: Added '.' (The muscles 27, 28, fig. 47, extend the
           lower limbs on the body, at the =hip.= The muscles 29, 30,
           31, fig. 46, extend the leg at the knee.)

  Page 84, Fig. 47: Added '.' (The muscles 29, 30, fig. =47,= bend the
           leg at the knee. The muscles 34, 36, fig. 46, bend the foot
           at the ankle, and extend the toes.)

  Page 88: Added '?' (What class of pupils should have recesses most
           =frequently?= 179. What effect has continued muscular
           contraction?)

  Page 95: Added '.' (196. Give an instance of the different effects
           produced by the absence and presence of the mental
           =stimulus.=)

  Page 97, Fig. 49: Was '(1.' (the unnatural curved spinal column, and
           its relative position to the perpendicular, =1.= The lower
           limbs are curved at the knee)

  Page 98: Added comma. (In performing any labor, as in speaking,
           reading, singing, mowing, sewing, =&c.,= there will be less
           exhaustion)

  Page 100, Fig. 51: Added '.' (Fig. 51. An improper position in
            =sitting.=)

  Page 104: Added ',' (210. What is said of the lateral and oblique
            movements of the =arm,= hand, and fingers in writing? How
            is this shown by experiment?)

  Page 107, Fig. 55: Added '.' (_d_, _e_, The bicuspids. _f_, _g_, The
            molars, (double teeth.) _h_, The wisdom =teeth.=)

  Page 108, Fig. 56: Added '.' (=Fig.= 56. A side view of the body and
            enamel of a front tooth.)

  Page 108, Fig. 57: Added '.' (=Fig.= 57. A side view of a molar
            tooth. 1, The enamel. 2, The body of the tooth.)

  Page 108, Fig. 57: Added '.' (1, The enamel. 2, The body of the
            =tooth.= 3, The cavity in the crown of the tooth that
            contains the pulp.)

  Page 115, Fig. 59: Added '.' (=Fig.= 59. A side view of the face,
            oesophagus, and trachea.)

  Page 118: Was 'COECUM' (249. The =CÆCUM= is the blind pouch, or
            cul-de-sac, at the commencement of the large intestine.
            Attached to its extremity)

  Page 119: Was 'coecum' (is the mucous membrane sometimes called the
            villous coat? 249. Describe the =cæcum=.)

  Page 119, Fig. 61: Was 'coecum' (4, The appendix vermiformis. 5, The
            =cæcum=. 6, The ascending colon. 7, The transverse
            colon.)

  Page 120: Was 'coecum' (half shorter than the intestine, and give it
            a sacculated appearance, which is characteristic of the
            =cæcum= and colon.)

  Page 127: Moved up from the following box. (What is said in regard
            to the bile? 266. What becomes of the chyle? =Of the
            residuum?=)

  Page 128, Fig. 65: Added '.' (Fig. 65. An ideal view of the organs
            of digestion, opened nearly the whole =length.=)

  Page 128, Fig. 65: Added '.' (1, The upper jaw. 2, The lower jaw. 3,
            The tongue. 4, The roof of the =mouth.= 5, The oesophagus.
            6, The trachea. 7, The parotid gland.)

  Page 128, Fig. 65: Added '.' (8, The sublingual =gland.= 9, The
            stomach. 10, 10, The liver. 11, The gall-cyst.)

  Page 128, Fig. 65: Added ',' (16, The opening of the small intestine
            into the large intestine. 17, 18, 19, =20,= The large
            intestine. 21, The spleen.)

  Page 128, Fig. 65: Added '.' (16, The opening of the small intestine
            into the large intestine. 17, 18, 19, 20, The large
            =intestine.= 21, The spleen.)

  Page 128, Fig. 65: Added '.' (21, The spleen. 22, The upper part of
            the spinal =column.=)

  Page 129: Was 'prope' (The food that is well masticated, and has
            blended with it a =proper= amount of saliva, will induce a
            healthy action in the stomach.)

  Page 129: Added '.' (will induce a healthy action in the =stomach.=
            Well-prepared chyme is the natural stimulus of the
            duodenum,)

  Page 129: Added ',' (Well-prepared chyme is the natural stimulus of
            the =duodenum,= liver, and pancreas; pure chyle is the
            appropriate excitant of)

  Page 131: Added '.' (another demand for food. What effect has
            increased exercise upon the system? =278.= How are the new
            particles of matter supplied? What does this induce?)

  Page 143: Was 'There fore' over line break. (digested becomes mixed
            with that last taken. =Therefore= the interval between
            each meal should be)

  Page 145: Added '.' (312. Why should they not be taken cold? Show
            some of the effects of improper food upon the inferior
            =animals.=)

  Page 153: Added '.' (=327.= Why does the position of a person affect
            digestion? 328. Into what are different kinds of aliment
            separated?)

  Page 154: Added ',' (333. The CIRCULATORY ORGANS are the _Heart_,
            =_Ar´te-ries_,= _Veins_, and _Cap´il-la-ries_.)

  Page 170, Fig. 75: Added '.' (=Fig.= 75. An ideal view of the
            circulation in the lungs and system. From the right
            ventricle of the heart)

  Page 179: Added '.' (the proper method of arresting the flow of
            blood from divided arteries. 382. The second incident.
            =383.= How should "flesh wounds" be dressed?)

  Page 182: Added '.' (What other vessels perform the office of
            absorption? Give observation. 389. Describe the
            =lymphatics.=)

  Page 186, Fig. 85: Added '.' (16, 17, 18, Of the face and neck. 19,
            20, Large =veins.= 21, The thoracic duct. 26, The
            lymphatics of the heart.)

  Page 189: Added '.' (matter formed in the system of the diseased
            person, may be more readily conveyed into their =own.=)

  Page 191: Was 'gen eral' over line. (every trifling and temporary
            enlargement, or tumor, is a cancer. Their =general= remedy
            is arsenic; and happy is the unfortunate sufferer)

  Page 191: Was 'suf ferer' over line. (arsenic; and happy is the
            unfortunate =sufferer= who escapes destruction in their
            hands, for too frequently)

  Page 191: Was 'frequent ly' over line. (happy is the unfortunate
            sufferer who escapes destruction in their hands, for too
            =frequently= their speedy cure is death.)

  Page 191: Was 'imme diately' over line. (413. In case of an
            accidental wound, it is best =immediately= to bathe the
            part thoroughly in pure water, and to)

  Page 192: Was 'Fol li-cles' (415. The SECRETORY ORGANS are the
            _Ex-ha´lants_, =_Fol´li-cles_=, and the _Glands_.)

  Page 192, Fig. 86: Added '.' (Fig. 86. A secretory follicle. An
            artery is seen, which supplies the material for its
            =secretion.= Follicles are also supplied)

  Page 193: Was 'mys terious' over line. (420. SECRETION is one of the
            most obscure and =mysterious= functions of the animal
            economy. "It is that process)

  Page 194: Was 'secre tion' over line. (420-431. _Give the physiology
            of the secretory organs._ 420. What is =secretion=?)

  Page 202: Was 'he' (Very soon, minute vessels shoot out from the
            living parts into =the= coagulum of the blood, and
            immediately commence their operations)

  Page 207: Added '?' (461. Mention another means by which the blood
            may be made impure. How =remedied?= 462. What is the
            effect of want of cleanliness upon the blood?)

  Page 208, Fig. 88: Added '.' (7, The right auricle of the heart. 8,
            The left auricle. 9, The pulmonary artery. 10, The aorta.
            11, The vena cava =descendens.= 12, The trachea.)

  Page 208, Fig. 88: Added '.' (16, 16, The right and left lobe of the
            liver. 17, The gall-cyst. 18, The =stomach.= 26, The
            spleen. 19, 19, The duodenum.)

  Page 208, Fig. 88: Added '.' (19, 19, The duodenum. 20, The
            ascending =colon.= 21, The transverse colon. 25, The
            descending colon.)

  Page 211, Fig. 90: Added '.' (10, Its lower lobe. 11, The upper lobe
            of the right =lung.= 12, The middle lobe. 13, The lower
            lobe.)

  Page 218: Was 'cavicle' (Those which are attached to the upper rib,
            sternum, and =clavicle=, contract and elevate the lower
            and free extremities of the ribs.)

  Page 220, Fig. 96: Added '.' (5, 5, The position of the walls of the
            abdomen in inspiration. 6, 6, The position of the
            abdominal walls in =expiration.=)

  Page 223: Was 'cabonic' (In addition, there is a small amount of
            vapor of water and =carbonic= acid. The pressure of this
            invisible)

  Page 225, Fig. 98: Added '.' (Fig. 98. 1, A bronchial tube divided
            into three branches. 2, 2, 2, =Air-cells.= 3, Branches of
            the pulmonary artery, that spread over the air-cells.)

  Page 226: Added 'to' (In a few hours, the blood next =to= the
            membrane will have become of a bright red color.)

  Page 227: Added '.' (reviewed from figs. 96, 97, and 99, or from
            anatomical outline plates Nos. 5 and =7.=)

  Page 232: Added '.' (503. Mention some reasons why different persons
            do not require the same amount of =air.=)

  Page 232: Added '.' (Give the illustration of the effects of impure
            air on lighted =lamps.=)

  Page 237: Added '.' (to connect with the outer walls of the building
            or external =air.= But if pure heated air is introduced
            into the room, it obviates)

  Page 241: Added '.' (What does fig. 100 represent? Fig. 101? Give
            observation =1st.=)

  Page 248: Added '.' (535. Mention some of the effects of mental
            depression upon the =body.= What is related by Lænnec?)

  Page 250: Was single-quote (Let another person press upon the
            projecting part of the neck, called "Adam's =apple,"=
            while air is introduced into the lungs through the
            bellows.)

  Page 263: Changed '.' to '?' (persons that have broad chests and
            voluminous lungs suffer less from cold than the
            narrow-chested with small =lungs?=)

  Page 269: Added '.' (still broader behind, where it is connected
            with the thyroid =cartilage.= Below, it connects with the
            first ring of the trachea.)

  Page 271: Was 'glot tis' (The aperture, or opening between these
            ligaments, is called the =_glot´tis_=, or _chink of the
            glottis_.)

  Page 276: Added '.' (vocal organs are in action, will induce too
            great a flow of blood to these parts, which will be
            attended by subsequent =debility.=)

  Page 289, Fig. 115: Added '.' (These ducts open into the sheath of
            the hair, (B.) All the figures, from 1 to 4, are magnified
            thirty-eight =diameters.=)

  Page 294: Added ';' (A proper thickness of the cuticle is in this
            manner =preserved;= the faculty of sensation and that of
            touch are properly regulated;)

  Page 326: Added '?' (What causes the edge of the nail "to grow into
            the flesh" of the =toe?= How prevented?)

  Page 329: Added '.' (731. What does the term brain designate? Name
            =them.= How are they protected? Describe fig. 120.)

  Page 330, Fig. 121: Added '.' (Fig. =121.= A section of the
            skull-bones and cerebrum. 1, 1, The skull.)

  Page 330, Fig. 121: Added '.' (1, 1, The skull. 2, 2, the dura
            =mater.= 3, 3, The cineritious portion of the cerebrum.)

  Page 330, Fig. 121: Added '.' (3, 3, The cineritious portion of the
            cerebrum. 4, 4, The medullary =portion.= The dark points
            indicate the position of divided blood-vessels.)

  Page 332: Added '.' (=733.= Describe the appearance of the brain
            when a horizontal section has been made. What is the gray
            border often called? What connects the)

  Page 333, Fig. 123: Added '.' (4, 4, The optic foramen in the
            sphenoid bone; through which passes the second pair of
            =nerves.= 5, 5, The sphenoidal fissure.)

  Page 334, Fig. 124: Added '.' (5, The corpus callosum. 6, The first
            pair of nerves. 7, The second =pair.= 8, The eye. 9, The
            third pair of nerves.)

  Page 334: Added '.' (738. Describe the dura mater. What is its use?
            Explain =fig.= 124.)

  Page 342: Added '.' (758. How many pairs of nerves issue from the
            spinal cord? Explain =fig.= 128. Fig. 129.)

  Page 347: Was '13 1-2' (The heaviest brain on record was that of
            Cuvier, which weighed 4 pounds and =13½= ounces.)

  Page 365: Added '.' (what age particularly is excessive and
            continued mental exertion hurtful? =813.= What is said of
            scrofulous and rickety children?)

  Page 369: Added '.' (the more repose they =require.= The organs of
            the child, beside sustaining their proper functions,)

  Page 385: Added '.' (868. What is the appearance of the surface of
            the tongue? Explain =fig.= 134.)

  Page 387: Added '.' (papillæ. 870. The fungiform papillæ? What nerve
            ramifies in the fungiform papillæ? How can these papillæ,
            or points, be seen? =871-875.= _Give the physiology of the
            organs of taste._ 871. Define taste.)

  Page 394: Added '.' (=892.= Describe the optic nerve. 893. Describe
            the globe of the eye.)

  Page 394: Added '.' (892. Describe the optic =nerve.= 893. Describe
            the globe of the eye.)

  Page 395, Fig. 137: Added '.' (7, 8, 9, 10, 11, 12, 13, The origin
            of several pairs of cranial =nerves.=)

  Page 396: Added '.' (In form, it is circular, convexo-concave, and
            resembles a =watch-glass.= It is received by its edge,
            which is sharp and thin, within the)

  Page 397, Fig. 138: Added '.' (a transverse section of the globe of
            the eye, seen from =within.= 1, The divided edge of the
            three coats--sclerotic)

  Page 399, Fig. 139: Added '.' (The cornea (This connects with the
            sclerotic coat by a bevelled edge.) 3, The choroid =coat.=
            6, 6, The iris. 7, The pupil.)

  Page 401: Added ',' (906. The PROTECTING ORGANS are the _Or´bits_,
            =_Eyebrows_,= _Eyelids_, and _Lach´ry-mal Apparatus_.)

  Page 401: Added '.' (covered with short, thick hairs, which form the
            upper boundary of the =orbits.= The eyebrows are so
            arranged)

  Page 401: Added '.' (909. Describe the =eyelids.= What is the use of
            the conjunctiva? How are the white spots frequently)

  Page 403: Added '.' (913. Describe the lachrymal =gland.= How many
            ducts pass from this gland, and what do they convey to
            the)

  Footnote 22: Added '.' (The refracting character of
            differently-formed lenses is illustrated in the works on
            Natural Philosophy, to which the pupil is =referred.=)

  Page 407, Fig. 142: Added '.' (Fig. 142. The forms of the different
            lenses. 1, A plane lens. 2, A globe =lens.= 3, A
            convexo-convex lens. 4, A plano-convex lens.)

  Page 407, Fig. 142: Added '.' (4, A plano-convex lens. 5, A
            concavo-concave =lens.= 6, A plano-concave lens. 7,
            Meniscus. 8, A concavo-convex lens.)

  Page 416: Changed '.' to '?' (Where is the wax of the ear
            =secreted?= 948. Describe the membrana tympani.)

  Page 417: Was ', 1,' (This figure is highly magnified. =1, 1,= The
            cochlea. 2, 3, Two channels, that wind two and a half
            turns around a central point)

  Page 421: Was 'Eustuchian' (This is the result of the air in the
            middle ear escaping through the =Eustachian= tube, when
            the vibrations of the membrana tympani are violent.)

  Page 422: Added '.' (969. Many of the parts just enumerated aid in
            hearing, but are not absolutely essential to this =sense.=
            But if the vestibule)

  Page 422: Added '.' (_Note._ Let the anatomy and physiology of the
            organs of hearing be reviewed, from fig. 148, or from
            anatomical outline plate No. =10.=)

  Page 439: Added '.' (know the proper mode of procedure in such
            cases, in order to render immediate assistance when within
            his =power.=)

  Page 441: Added '.' (=1035.= What is the antidote? 1036. What should
            immediately be done when arsenic is swallowed?)

  Page 441: Changed '.' to '?' (When magnesia cannot be obtained, what
            will answer as a =substitute?= 1050. What is the antidote
            when ley is swallowed?)

  Page 442: Changed '.' to '?' (What treatment should be adopted when
            an over-dose of opium or any of its preparations is
            =taken?= 1057. What is said of stramonium?)

  Page 443: Added '.' (lobelia, bloodroot, tobacco, &c., is taken?
            =1062.= Should a physician be called in all cases when
            poison is swallowed?)

  Page 444: Added '.' (CASEINE is abundantly found in milk. When
            dried, it constitutes =cheese.= Alcohol, acids, and the
            stomach of any of the mammalia coagulate it; and)

  Page 444: Added '.' (canal pass slowly through this portion. The
            _rectum_ is named from the straight direction that it
            assumes in the latter part of its =course.=)

  Page 445: Was 'a' (This is called the peristaltic, or vermicular
            motion. The great length of intestine in =all= animals,
            and especially in the herbivorous ones, is owing to the
            necessity of)

  Page 448: Added '.' (and often inspiring more deeply than is common
            in older =persons.= Also, if the carbon of the food does
            not have a requisite supply of oxygen)

  Page 451: Added '.' (=AB-DUC´TOR.= [L. _abduco_ to lead away.] A
            muscle which moves certain parts,)

  Page 452: Original looks like 'Arbør'. (AR´BOR. [L.] A tree.
            _=Arbor= vitæ._ The tree of life. A term applied to a
            part)

  Page 452: Added ',' (BRE´VIS. [L.] _Brevis_, short; =_brevior_,=
            shorter.)

  Page 452: Added ']' (CAP´IL-LA-RY. [L. _capillus_, a =hair.]=
            Resembling a hair; small.)

  Page 454: Added '.' (Having the quality of exhaling or
            =evaporating.=)

  Page 457: Added '.' (MI´TRAL. [=L.= _mitra_, a mitre.] The name of
            the valves in the left side of)

  Page 458: Added '.' (=O-MEN´TUM.= [L.] The caul.)

  Page 458: Added '.' (=OP-PO´NENS.= That which acts in opposition to
            something. The name of two)

  Page 458: Added '.' (OX-AL´IC. Pertaining to sorrel. _Oxalic acid_
            is the acid of =sorrel.= It is composed of two equivalents
            of carbon)

  Page 458: Added '.' (invisible and inodorous. One of the components
            of atmospheric =air.=)

  Page 458: Added '.' (PEC´TUS. [L.] The =chest.=)

  Page 458: Added '.' (PEC´TO-RAL. Pertaining to the =chest.=)

  Page 459: Added '.' (PLEX´US, [L. _plecto_, to weave =together.=]
            Any union of nerves, vessels, or fibres,)

  Page 459: Added '.' (POS´TI-CUS. [L.] Behind; =posterior.= A term
            applied to certain muscles.)

  Page 459: Added '.' (The muscle of the forearm that moves the palm
            of the hand =downward.=)

  Page 460: Added '.' (=RA-DI-A´LIS.= Radial; belonging to the
            radius.)

  Page 460: Added '.' (RA´MUS. [L.] A branch. A term applied to the
            projections of =bones.=)

  Page 460: Added '.' (=SEP´TUM.= [L.] A membrane that divides two
            cavities from each other.)

  Page 462: Was 'Be longing' over line. (VIT´RE-OUS. [L. _vitrum_,
            glass.] =Belonging= to glass. A humor of the eye.)

  Page 462: Removed comma: was 'L.,' (VO´MER. [=L.= a ploughshare.]
            One of the bones of the nose.)

  Page 464: Added ',' (=----,= Physiology of the, 164)

  Page 464: Added ',' (=----,= Hygiene of the, 172)

  Page 464: Added ',' (----, Influence =of,= on the Circulation, 173)

  Page 465: Added ',' (=MEDIASTINUM,= 211)

  Page 465: Added ',' (MEDULLA =OBLONGATA,= 333)

  Page 466: Added ',' (PRESERVATION OF =HEALTH,= 425)

  Page 466: Substituted 'Spinal' for the repeat line. (=SPINAL= CORD,
            36, 340)

  Page 467: Added comma (_Bones of the Head._ 7, The sphenoid bone.
            =8,= The frontal bone. 10, The parietal bone. 11, The os
            unguis. 12, The superior maxillary bone,)

  Page 468: Added ',' (41, 41, The bones of the =metatarsus,= (middle
            of the foot.) 42, 42, The bones of the toes.)

  Page 469: Added '.' (27, 28, Ligaments that connect the clavicle
            and =scapula.= 29, The capsular ligament of the
            shoulder-joint.)

  Page 469: Added '.' (9, Tendon of the gluteus =muscle.= 35, The
            capsular ligament of the hip-joint.)

  Page 469: Added '.' (37, The ligament that connects the tibia and
            =fibula.= 38, The interosseous ligament.)

  Page 469: Added '.' (38, The interosseous ligament. 39, 40,
            Ligaments of the =ankle-joint.=)

  Page 469: Added '.' (PLATE =III.=)

  Page 469: Added '.' (_Muscles of the Head and Neck._ 7, The
            sterno-mastoideus =muscle.= 8, The sterno-hyoideus muscle.
            9, The omo-hyoideus muscle. 10, The)

  Page 469: Added '.' (16, The zygomatic muscle. 17, The depressor of
            the lower =lip.= 18, The depressor anguli oris muscle. 19,
            The triangular muscle of the)

  Page 469: Added '.' (43, The sartorius muscle. 44, The rectus
            femoris muscle. 45, The vastus externus =muscle.= 46, The
            vastus internus muscle.)

  Page 469: Added '.' (46, The vastus internus muscle. 47, The
            internal straight =muscle.= 48. The pectineus muscle. 49,
            The adductor muscle. 50, The psoas muscle.)

  Page 470: Added '.' (56, 57, The gastrocnemii muscles. 58, The long
            flexor muscle of the great =toe.= 69, The short extensor
            muscles of the toes.)

  Page 470: Added '.' (_Muscles of the Lower Extremities._ 29, The
            gluteus maximus =muscle.= 30, The gluteus medius muscle.
            31, The biceps flexor cruris muscle.)

  Page 471: Added '.' (10, The pharynx. 11, The =oesophagus.= 12, The
            upper portion of the spinal column. C, The spinal cord.)

  Page 471: Added '.' (1, 1, 1, An outline of the right lung. 2, 2, 2,
            An outline of the left =lung.= 3, The larynx. 4, The
            trachea.)

  Page 472: Added '.' (_Arteries of the Neck and =Head.=_ 15, The
            right carotid artery. 16, The left carotid artery.)

  Page 472: Added '.' (The capillary vessels of the =lungs.= P, P, P,
            The right pulmonary vein. Q, Q, The left pulmonary vein.)

  Page 473: Unclear in original (10, The median nerve. G, The
            =circumvex= nerve of the shoulder.)

  Page 474: Added ',' (8, 8, =8,= 8, 8, 8, 8, 8, Perspiratory glands
            and their ducts. 9, 9, 9, 9, 9, Nerves of the)

  Page 475: Added '.' (8, 8, The tympanum, (middle ear.) 4, The
            =malleus.= 5, The incus. 6, The orbicularis.)





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