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Title: Physiological Researches on Life and Death
Author: Bichat, Xavier
Language: English
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PHYSIOLOGICAL RESEARCHES
ON
LIFE AND DEATH,
BY XAVIER BICHAT;
Translated from the French,
BY F. GOLD,
MEMBER OF THE ROYAL COLLEGE OF SURGEONS, LONDON:
WITH NOTES,
BY F. MAGENDIE,
Member of the Institute and of the Royal Academy of Medicine.
_THE NOTES TRANSLATED_
BY GEORGE HAYWARD, M. D.
BOSTON:
PUBLISHED BY RICHARDSON AND LORD.
J. H. A. FROST, PRINTER.
1827.
DISTRICT OF MASSACHUSETTS: _to wit_.
_District Clerk’s Office._
BE IT REMEMBERED, That on the seventeenth day of December, A. D.
1827, in the fifty-second year of the Independence of the United
States of America, RICHARDSON & LORD, of the said District, have
deposited in this office the title of a book, the right whereof
they claim as proprietors, in the words following, _to wit_:
“Physiological Researches on Life and Death, by Xavier Bichat;
translated from the French, by F. Gold, member of the Royal
College of Surgeons, London, with notes, by F. Magendie, member
of the Institute and of the Royal Academy of Medicine. The notes
translated by George Hayward, M. D.”
In conformity to the Act of the Congress of the United States,
entitled, “An Act for the encouragement of Learning, by securing
the copies of Maps, Charts and Books, to the Authors and
Proprietors of such Copies, during the times therein mentioned:”
and also to an Act entitled, “An Act supplementary to an Act,
entitled, An Act for the encouragement of Learning, by securing the
Copies of Maps, Charts and Books, to the Authors and Proprietors of
such Copies during the times therein mentioned; and extending the
benefits thereof to the Arts of Designing, Engraving and Etching
Historical and other Prints.”
JOHN W. DAVIS,
_Clerk of the District of Massachusetts_
TRANSLATOR’S PREFACE.
The Translator of the Work which is here offered to the Public,
feels it quite unnecessary to expatiate upon the merits of its
Author, whose ideas and classifications in Physiology are now
very generally adopted. He has supposed, however, that the
experiments which constitute the _Second_ Part of the Work, are
not so familiar to Professional Men, as many of the conclusions
which have been deduced from them, and therefore has presumed
that a greater publicity of these experiments will by no means be
unserviceable. Dr. Kentish, in his account of Baths, has mentioned
the circumstances which led to this translation.
ADVERTISEMENT BY THE FRENCH EDITOR.
The work of Bichat, which appears to the most advantage, is the
one that we now reprint; his observing mind, his experimental
genius and his lucid manner of exhibiting facts are particularly
observable in it. This work will have for a very long time a great
influence on physiologists and physicians.
The Physiological Researches on Life and Death have had more
than one class of admirers. Exact minds, friends of the progress
of science have praised it for the great number of accurate
observations which it contains, the ingenious management of the
experiments and the correctness of the deductions; but they have
regretted that the author constantly placed life in opposition to
physical laws, as if living beings were not bodies before they were
vegetables or animals. They have seen with regret that he offered
illusory explanations of inexplicable phenomena.
These grounds of legitimate criticism seem to have been the reason
of the enthusiasm of another class of readers, for whom whatever is
vague appears to have a great degree of attraction. The readers,
of whom I have just spoken, feeling but little interest in the new
facts which the Physiological Researches contain, have adopted
without examination its fallacious hypotheses, and attaching
to them an importance which the author never did, because they
believed that they elucidated the mechanism of the most obscure
vital operations, and conducted to a true theory of medicine.
Should we lament this errour? Certainly not, as it has powerfully
contributed to the brilliant success of Bichat’s work, and by means
of some errours, much truth has been promulgated.
As the works of Bichat have now become classics and their
reputation cannot be increased, it is time to place young students
on their guard against the errours into which the imagination of
the author led him, and which are the more to be feared, as Bichat
in order to convince, has employed all the fascinations of his
animated style.
The memory of Bichat cannot but gain by it; the numerous truths
which he has discovered will shine with a brighter light, when
freed from the light shades that envelope them.
Such is the object of the notes to the present edition, which we
have endeavoured to bring up to the present state of knowledge.
CONTENTS OF THE WORK.
PART THE FIRST.
CHAPTER I.
Page
Division of Life into Animal and Organic Life 11
CHAPTER II.
General Differences of the two Lives, with regard to the outward
form of their respective Organs 18
CHAPTER III.
General Differences of the two Lives, with regard to the mode of
action of their respective Organs 25
CHAPTER IV.
General Differences of the two Lives with respect to Duration of
Action 40
CHAPTER V.
General Differences of the two Lives with respect to Habit 46
CHAPTER VI.
General Differences of the two Lives with respect to Mental
Affection 54
CHAPTER VII.
General Differences of the two Lives with respect to Vital Power 76
CHAPTER VIII.
Of the Origin and Development of the Animal Life 132
CHAPTER IX.
Of the Origin and Development of the Organic Life 156
CHAPTER X.
Of the Natural Termination of the Two Lives 163
PART THE SECOND.
CHAPTER I.
Page
General Considerations on Death 173
CHAPTER II.
Of the Influence of the Death of the Heart over that of the Brain 176
CHAPTER III.
Of the Influence of the Death of the Heart over that of the Lungs 192
CHAPTER IV.
Of the Influence of the Death of the Heart over that of all the
Organs 194
CHAPTER V.
Of the Influence of the Death of the Heart, as to the production
of General Death 202
CHAPTER VI.
Of the Influence of the Death of the Lungs over that of the Heart 210
CHAPTER VII.
Of the Influence of the Death of the Lungs over that of the Brain 237
CHAPTER VIII.
Of the Influence of the Death of the Lungs over that of the
Organs in general 252
CHAPTER IX.
Of the Influence of the Death of the Lungs over the General Death
of the Body 276
CHAPTER X.
Of the Influence of the Death of the Brain over that of the Lungs 297
CHAPTER XI.
Of the Influence of the Death of the Brain over that of the Heart 305
CHAPTER XII.
Of the Influence of the Death of the Brain over that of all the
Organs 318
CHAPTER XIII.
Of the Influence of the Death of the Brain over that of the Body
in General 332
PHYSIOLOGICAL RESEARCHES
ON
LIFE AND DEATH.
PART THE FIRST.
CHAPTER I.
GENERAL DIVISION OF LIFE.[1]
The definition of life is usually sought for in abstract
considerations; it will be found, if I mistake not, in the
following general expression:--Life consists in the sum of the
functions, by which death is resisted.[2]
In living bodies, such in fact is the mode of existence, that
whatever surrounds them, tends to their destruction. They are
influenced incessantly by inorganic bodies; they exercise
themselves, the one upon the other, as constant an action; under
such circumstances they could not long subsist, were they not
possessed in themselves of a permanent principle of reaction. This
principle is that of life; unknown in its nature, it can be only
appreciated by its phenomena: an habitual alternation of action
and reaction between exterior bodies, and the living body, an
alternation, of which the proportions vary according to the age of
the latter, is the most general of these phenomena.
There is a superabundance of life in the child: In the child, the
reaction of the system is superior to the action, which is made
upon it from without. In the adult, action and reaction are on
a balance; the turgescence of life is gone. In the old man, the
reaction of the inward principle is lessened, the action from
without remaining unaltered; it is then that life languishes, and
insensibly advances towards its natural term, which ensues when all
proportion ceases.
The measure, then, of life in general, is the difference which
exists between the effort of exterior power, and that of interior
resistance. The excess of the former is an indication of its
weakness; the predominance of the latter an index of its force.
I. _Division of Life into Animal and Organic Life._[3]
Such is life considered in the aggregate; examined more in detail
it offers us two remarkable modifications, the one common to the
vegetable and the animal; the other belonging exclusively to
the latter. In comparing two individuals from each of the living
kingdoms, the one will be seen existing only within itself, having
with what surrounds it the relations only of nutrition, attached to
the soil, in which its seed has been implanted, born there, growing
there, and perishing there. The other will be observed combining
with this interior life, which in the highest degree it enjoys,
an exterior life by which it acquires a very numerous series of
relations with all surrounding bodies, a life, which couples it to
the existence of every other being, by which it is approximated, or
removed from the objects of its desires or its fears, and seems in
appropriating every thing in nature to itself, to consider every
thing with regard to its individual existence only.[4]
Thus it might be said, that the vegetable is only the sketch, or
rather the ground-work of the animal; that for the formation of the
latter, it has only been requisite to clothe the former with an
apparatus of external organs, by which it might be connected with
external objects.
From hence it follows, that the functions of the animal are of
two very different classes. By the one (which is composed of an
habitual succession of assimilation and excretion) it lives within
itself, transforms into its proper substance the particles of
other bodies, and afterwards rejects them when they are become
heterogeneous to its nature. By the other, it lives externally, is
the inhabitant of the world, and not as the vegetable of a spot
only; it feels, it perceives, it reflects on its sensations, it
moves according to their influence, and frequently is enabled to
communicate by its voice its desires, and its fears, its pleasures,
and its pains.
The aggregate of the functions of the first order, I shall name
the organic life, because all organized beings, whether animal or
vegetable, enjoy it more or less, because organic texture is the
sole condition necessary to its existence. The sum of the functions
of the second class, because it is exclusively the property of the
animal, I shall denominate the animal life.
The series of the phenomena of these two lives, relate to the
individual. Generation, as a function, regards the species, and
thus has no place among them. Its connections with the greater
number of the other functions are but very indirect; it commences a
long time after them, it is extinct a long time before them. In the
greater number of animals the periods of its activity are separated
by long intervals of time, and during these, it is absolutely null.
Even in man, with whom the remissions of its impulses, are much
less durable, it has not a much more extensive connexion with the
rest of the system. Castration is almost always marked by a general
increase of the nutritive process; the eunuch, enjoying indeed a
less degree of vital energy, but the phenomena of his life being
displayed with a greater exuberance. We shall here, then, lay aside
the consideration of the laws which give us existence, and occupy
ourselves alone on those which maintain us in existence. Of the
former we shall speak hereafter.
II. _Subdivision of each of the two lives into two orders of
functions._
The animal and the organic life, are each of them composed of two
orders of functions, which succeed each other, and are concatenated
in an inverse direction.
In the animal life, the first order is established from the
exterior of the body, towards the brain; the second from the brain
towards the organs of locomotion and the voice. The impression of
objects successively affects the senses, the nerves and the brain.
The first receive, the second transmit, the third perceives the
impression. The impression, in such way, received, transmitted, and
perceived, constitutes sensation.
The animal, in the first order of these functions, is almost
passive; in the second, he becomes active.--This second order is
the result of the successive actions of the brain (where volition
has been produced in consequence of the previous sensation) of the
nerves, which transmit such volition, and of the locomotive organs
and voice, which are the agents of volition. External bodies act
upon the animal by means of the first order of these functions, the
animal reacts upon them by means of the second.
In general there exists between the two orders a rigorous
proportion; where the one is very marked, the other is put forth
with energy. In the series of living beings, the animal, which
feels the most, moves also the most. The age of lively perception,
is that also of vivacity of motion; in sleep, where the first
order is suspended, the second ceases, or is exercised only
with irregularity. The blind man, who is but half alive to what
surrounds him, moves also with a tardiness which would very soon be
lost, where his exterior communications to be enlarged.
A double movement is also exercised in the organic life; the one
composes, the other decomposes the animal. Such is the mode of
existence in the living body, that what it was at one time it
ceases to be at another. Its organization remains unaltered, but
its elements vary every moment. The molecules of its nutrition by
turns absorbed and rejected, from the animal pass to the plant,
from the plant to inorganic matter, return to the animal, and so
proceed in an endless revolution.
To such revolution the organic life is well adapted. One order
of its functions assimilates to the animal the substances which
are destined to nourish him; another order deprives him of these
substances, when, after having for some time made a part of it,
they are become heterogeneous to his organization.
The first, which is that of assimilation, results from the
functions of digestion, circulation, respiration, and nutrition.
Every particle, which is foreign to the body before it becomes an
element of it, is subject to the influence of these four functions.
When it has afterwards concurred for some time to the formation of
the organs, the absorbents seize on it, and throw it out into the
circulatory torrent, where it is carried on anew, and from whence
it issues by the pulmonary or cutaneous exhalations, or by the
different secretions by which the fluids are ejected from the body.
The second order, then, of the functions of the organic life,
or that of decomposition, is formed of those of absorption,
circulation, exhalation, and secretion.
The sanguiferous system, in consequence, is a middle system, the
centre of the organic life, as the brain is the centre of the
animal life. In this system the particles, which are about to be
assimilated, are circulated and intermixed with those, which having
been already assimilated, are destined to be rejected; so that
the blood itself is a fluid composed of two parts; the one, the
pabulum of all the parts of the body, and derived from the aliment;
the other, excrementitious, composed of the wrecks and residue
of the organs, and the source of the exterior secretions and
exhalations.--Nevertheless these latter functions serve also, at
times, the purpose of transmitting without the body, the products
of digestion, although such products may not have concurred to the
nourishments of the parts. This circumstance may be observed when
urine and sweat are secreted after copious drinking. The skin and
the kidneys being at such times the excreting organs, not of the
matter of the nutritive, but of that of the digestive process; the
same also may be said of the milk of animals, for this is a fluid
which certainly has never been assimilated.[5]
There does not exist between the two orders of the functions of the
organic life the same relation, which takes place between those
of the animal life. The weakness of the first by no means renders
absolutely necessary a decrease of action in the second. Hence
proceed marasmus and leanness, states, in which the assimilating
process ceases in part, the process of excretion remaining
unaltered.
Let us leave, then, to other sciences, all artificial method, but
follow the concatenation of the phenomena of life, for connecting
the ideas which we form of them, and we shall perceive, that the
greater part of the present physiological divisions, afford us but
uncertain bases for the support of any thing like a solid edifice
of science.
These divisions I shall not recapitulate; the best method of
demonstrating their inutility will be, if I mistake not, to prove
the solidity of the division, which I have adopted. We shall now
examine the great differences, which separate the animal existing
without, from the animal existing within, and wearing itself away
in a continual vicissitude of assimilation and excretion.
FOOTNOTES:
[1] The form adopted by Bichat, in this work, has been much blamed
by some, and extravagantly praised by others. The blame and the
praise appear to me to be equally misplaced. His object was to
exhibit the various phenomena of life; the order in which this
was to be done was a matter of indifference. If Bichat gave a
preference to this form, it was because it was conformable to the
nature of his mind; and he accomplished his task in a very happy
manner. The division that he has adopted is not new, it may be
found, with slight modifications, in writers of different periods,
and even in Aristotle. Besides, it is not necessary in the sciences
to attach a very great importance to classification. All these
contrivances have been invented only to aid the memory; and the
functions of living bodies are not so numerous, as to render it
necessary in studying them to lean upon systematic divisions.
[2] The word _life_ has been employed by physiologists in two
different senses. With some, it means an imaginary being, the sole
principle of all the functions which living bodies exhibit; with
others, it means only the assemblage of these functions. It is
in this last sense that Bichat employs it. This is what he means
to say in the following sentence. _Life is the assemblage of the
functions which resist death._ He is wrong only in allowing the
idea of death to enter into it; for this idea necessarily supposes
that of life. There is then really a bad circle in this definition;
but in putting aside what is defective in the expression, it may be
seen that Bichat considers life as a result, not as a cause.
Before and since the time of Bichat, a great number of definitions
of life has been given, which are either false or incomplete. It
should not be required of a definition, that it should give all
the properties of the thing which it is designed to make known,
this would be a description; but we have a right to expect that it
should assign to this thing certain characters which belong to it
alone, and thus distinguish it from every thing else.
Let us examine by this principle the definition adopted in a modern
work. _Life_, it is said, _is the assemblage of the phenomena which
succeed each other, for a limited time, in an organized being_.
This is no doubt true of life; but, if it can also be applied to
another state, it ceases to be a definition. An animal has just
died; its organs from that moment are subject to the action of
chemical affinities only; decomposition takes place, gases are
disengaged, fluids flow out and new solid aggregates are formed.
After a time every molecular motion ceases; there remains only a
certain number of binary, ternary combinations, &c. Here then is
an _assemblage of phenomena taking place for a limited time in an
organized body_, and yet it is not life.
[3] This distinction of the two lives is bad, inasmuch as it tends
to separate phenomena which have a very intimate connexion, which
relate to a common object, and which are often produced by means in
every respect similar. Why should I rank among the organs of animal
life the muscular apparatus which carries the alimentary mass
from the mouth into the oesophagus, and among those of the other
life, that which takes it from the cardiac orifice to the anus? Is
not the action of the first apparatus in relation with nutrition
as well as the action of the last, and does not the muscular
apparatus of the oesophagus act upon a body which is foreign to us,
as well as that of the tongue and the pharynx? Do the motions of
mastication differ in their object from those of which we have just
spoken, and as to the means of execution, does not the muscular
action still perform the principal part?
We might in the same way bring near each other the motions by
means of which we seize our food. The action itself of the senses,
which directs these motions, is, with nutrition, in a relation
more remote, but not less necessary, and we see in the various
classes of animals that their apparatus is modified according to
the different kinds of nourishment. If the distinction of the two
lives be wanting in justice, as to the object of the functions it
separates, we shall soon see that the characters attached to the
organs of one and the other do not establish this division in a
more striking manner.
[4] This division between vegetables and animals is far from being
so striking as is here supposed; these two classes of beings,
so different when we examine them in the individuals endowed
with a very complicated organization, approximate each other
in a remarkable degree, when we descend to those species whose
structure is most simple; it is even remarkable that the most
constant character which distinguishes one from the other, is not
found in the organs of animal life, but in those of vegetable or
organic life. The senses are one after the other found wanting;
for in an individual in whom we can discover no nervous system,
there is no more reason to suppose the existence of the sense of
touch as a sensation, than to suppose it in the sensitive plant,
the dionæa muscipula, and other similar plants; we see only action
and reaction. The motions of the arms of certain polypi no more
suppose volition than the motion of the root which follows a wet
sponge, or that of the branches which turn towards the light;
the only very constant character is the absence or presence of a
digestive cavity. To speak of an animal as a vegetable clothed with
an external apparatus of organs of relation, is a more brilliant
than profound view of the subject. Buisson, who, in his division
of the physiological phenomena, avoids this inaccuracy, has
himself fallen into error; he pretends that respiration belongs
exclusively to animals; and that thus the division of Bichat was
not only unfounded but also incomplete, since this function,
which is neither of vegetation nor of relation, could be ranked
under neither life. Buisson was not well informed; no doubt the
respiration of vegetables does not exhibit the most apparent
phenomena of the respiration of the mammalia, but every thing,
which essentially constitutes the function, is found in the one as
well as in the other; absorption of the atmospheric air, and the
formation and exhalation of a new gas; the rest is only accidental
and is not an appendage but in certain classes of animals. In some
reptiles, though we find a particular organ for respiration, this
organ is not indispensable; it may be removed, and the skin becomes
the only respiratory organ; and when finally we come to consider
animals with _tracheæ_, we see that the conformity becomes more and
more evident.
[5] Bichat seems here to adopt the generally received opinion
that it is the chyle which furnishes to the mammary gland the
materials of which the milk is composed. We know not whence this
opinion arises, if it be not from the gross resemblance which the
chyle and milk often exhibit. This resemblance, if it were very
great, would be a poor reason for admitting, without anatomical
proof, so singular a fact; but it is very far from being perfect.
The chyle in fact does not exhibit the milky appearance and the
white opaque colour, only when the animal from whom it is taken,
has fed upon substances containing fat; in all other cases, it is
almost transparent; its odour and taste, under all circumstances,
differ entirely from those of milk; if these two fluids are left
to themselves, the milk remains a long time without coagulating,
but the chyle almost immediately coagulates, and then separates
into three parts. The solid portion soon exhibits cells, and an
appearance of organization; nothing similar is seen in the coagulum
of milk; the serum of the milk remains colourless when exposed
to the simple contact of the air, that of the chyle assumes a
rosy tint, often very vivid. Finally, if we examine the chemical
composition of these two fluids, we shall find in them differences
still more striking. (See for farther details, my Elements of
Physiology, Vol. 2d.)
CHAPTER II.
GENERAL DIFFERENCES OF THE TWO LIVES WITH REGARD TO THE OUTWARD
FORM OF THEIR RESPECTIVE ORGANS.
The organs of the animal life are symmetrical, those of the organic
life irregular in their conformation; in this circumstance consists
the most essential of their differences. Such character, however,
to some animals, and among the fish, to the sole and turbot
especially, is not applicable; but in man it is exactly traced, as
well as in all the genera which are nearest to him in perfection.
In them alone am I about to examine it.
I. _Symmetry of the external forms of the animal life._[6]
Two globes in every respect the same, receive the impressions of
light. Sounds and odours, have also their double analogous organ.
A single membrane is affected to savours, but the median line is
manifest upon it, and the two segments, which are indicated by it,
are exactly similar. This line indeed is not every where to be seen
in the skin, but it is every where implied. Nature, as it were,
has forgotten to describe it, but from space to space she has laid
down a number of points, which mark its passage. The cleft at the
extremity of the nose, of the chin, and the middle of the lips, the
umbilicus, the seam of the perineum, the projection of the spinous
apophyses of the back, and the hollow at the posterior part of the
neck are the principal points at which it is shewn.
The Nerves, which transmit the impressions received by the senses,
are evidently assembled in symmetrical pairs.
The brain, the organ (on which the impressions of objects are
received) is remarkable also for the regularity of its form. Its
double parts are exactly alike, and even those which are single,
are all of them symmetrically divided by the median line.
The Nerves again, which transmit to the agents of locomotion and of
the voice, the volitions of the brain, the locomotive organs also,
which are formed in a great degree of the muscular system, of the
bony system, and its dependencies, these together with the larynx
and its accessories, composing the double agents of volition, have
all of them a regularity, a symmetry, which are invariable.
Such even is the truth of the character which I am now describing,
that the muscles and the nerves immediately cease to be regular,
as soon as they cease to appertain to the animal life. The heart,
and the muscular fibres of the intestines are proofs of this
assertion in the muscles; in the nerves, the great sympathetic, is
an evidence of its truth.
We may conclude then from simple inspection, that Symmetry is the
essential character of the organs of the animal life of man.
II. _Irregularity of the exterior forms of the organic life._
If at present we pass to the viscera of the organic life, we shall
perceive a character directly the contrary of the former. The
stomach, the intestines, the spleen, the liver, &c. are all of them
irregularly disposed.
In the system of the circulation, the heart and the large vessels,
such as the upper divisions of the aorta, the vena azygos, the vena
portæ, and the arteria innominata have no one trace of symmetry.
In the vessels of the extremities continual varieties are also
observed, and when they occur, it is particularly remarkable that
their existence on one side in no way affects the other side of the
body.
The apparatus of respiration appears indeed at first to be exactly
regular; nevertheless, the bronchi are dissimilar in length,
diameter, and direction; three lobes compose one of the lungs,
two the other: between these organs also, there is a manifest
difference of volume; the two divisions of the pulmonary artery
resemble each other neither in their course, nor in their diameter;
and the mediastinum is sensibly directed to the left. We shall thus
perceive that symmetry is here apparent only, and that the common
law has no exception.
The organs of exhalation and absorption, the serous membranes, the
thoracic duct, the great right lymphatic vessel, and the secondary
absorbents of all the parts have a distribution universally unequal
and irregular.
In the glandular system also we see the crypts, or mucous follicles
disseminated in a disorderly manner in every part; the pancreas,
the liver, the salivary glands themselves, though at first sight
more symmetrical, are not exactly submitted to the median line;
added to this, the kidneys differ from each other in their
situation, in the length and size of their artery and vein, and in
their frequent varieties more especially.[7]
From considerations so numerous we are led to a result exactly the
reverse of the preceding one; namely, that the especial attribute
of the organs of the interior life is irregularity of exterior form.
III. _Consequences resulting from the difference of exterior form
in the organs of the two lives._
It follows from the preceding description, that the animal life is
as it were double; that its phenomena performed as they are at the
same time on the two sides of the body, compose a system in each of
them independent of the opposite system; that there is a life to
the right, a life to the left; that the one may exist, the other
ceasing to do so, and that they are doubtless intended reciprocally
to supply the place of each other.
The latter circumstance we may frequently observe in those morbid
affections so common, where the animal sensibility and mobility
are enfeebled, or annihilated on one side of the body, and capable
of no affection whatever; where the man on one side is little more
than the vegetable, while on the other he preserves his claim to
the animal character. Undoubtedly those partial palsies, in which
the median line, is the limit where the faculties of sensation and
motion finish, and the origin from whence they begin can never be
remarked so invariably in animals, which, like the oyster, have an
irregular exterior.
On the contrary the organic life is a single system, in which
every thing is connected and concatenated; where the functions on
one side cannot be interrupted, and those on the other subsist. A
diseased liver influences the state of the stomach; if the colon on
one side cease to act, that upon the other side cannot continue in
action: the same attack, which arrests the circulation in the right
side of the heart, will annihilate it also in the left side of the
heart. Hence it follows, the internal organs on one side being
supposed to suspend their functions, that those on the other must
remain inactive, and death ensue.
This assertion, however, is a general one; it is only applicable
to the sum of the organic life, and not to its isolated phenomena.
Some of them in fact are double, and their place may be
supplied--the kidneys and lungs are of this description.
I shall not enquire into the cause of this remarkable difference,
which in man, and those animals which approach him the nearest,
distinguishes the organs of the two lives. I shall only observe,
that it enters essentially into the nature of their phenomena, and
that the perfection of the animal functions is so connected with
the general symmetry observed in their respective organs, that
every thing which troubles such symmetry, will more or less impair
the functions.
It is from thence, no doubt, that proceeds this other difference
of the two lives, namely, that nature very rarely varies the usual
conformation of the organs of the animal life. Grimaud has made
this observation, but has not shewn the principle on which it
depends.
It is a fact, which cannot have escaped any one the least
accustomed to dissection, that the spleen, the liver, the stomach,
the kidneys, the salivary glands, and others of the internal life,
are frequently various in form, size, position, and direction.
Such in the vascular system are these varieties, that scarcely
will any two subjects be found exactly alike under the scalpel of
the anatomist: the organs of absorption, the lymphatic glands in
particular, are rarely the same either in number or volume, neither
do the mucous glands in any way affect a fixed and analogous
situation.
And not only is each particular system subject to frequent
aberrations, but the whole of the organs of the internal life are
sometimes found in the inverse of the natural order. Of this I have
lately seen an instance.
Let us now consider the organs of the animal life, the senses, the
brain, the voluntary muscles, and the larynx: here every thing
is exact, precise, and rigourously determined. In these there
is scarcely ever seen a variety of conformation; if there do
exist any, the functions are troubled, disturbed, or destroyed:
they remain unaltered in the organic life, whatever may be the
disposition of the parts.
The difference with respect to action, in the organs of the two
lives, depends, undoubtedly, upon the symmetry of the one, whose
functions the least change of conformation would have disturbed,
and on the irregularity of the other, with which these different
changes very well agree.
The functions of every organ of the animal life are immediately
connected with the resemblance of the organ to its fellow on
the opposite side if double, or if single to its similarity of
conformation in its two halves: from hence the influence of organic
changes upon the derangement of the functions may be well conceived.
But this assertion will become more sensible, when I shall have
pointed out the relations which exist between the symmetry and the
irregularity of the organs, and the harmony and the discordance of
their functions.
FOOTNOTES:
[6] It is rather to the external forms that symmetry appears
to have been primitively attached, and it is in some measure
accidentally and because the nature of their functions requires
in general that they should be placed on the exterior, that the
organs of relation are found modified in virtue of this law. In
the example cited, of fishes without a bladder, the eyes, to lose
nothing of their utility, must be differently placed, and on the
face, which alone is in relation with the light; yet even in this
case, the symmetry of external forms has been displaced rather
than destroyed, and at the first examination it seems complete.
When the organs of relation are found placed on the interior, they
frequently exhibit some irregularity, and to take an example of
a known animal, the organ of voice, in the male duck, is a very
remarkable one; in man even, the wind-pipe is not symmetrical,
after it arrives at the first division of the bronchia. On the
contrary, among the organs of the other life, those which are
prominent on the exterior, constantly present the symmetrical
character, as the thyroid gland; the mammary glands, &c.
[7] If we deny symmetry to the kidneys, because they are not
uniformly composed of the same number of lobes in children, we must
deny it also to the brain, the two lobes of which never exhibit the
same arrangement in their circumvolutions; if we deny it to the
salivary glands, because one is larger than the other, we must deny
it to the extremities, because the right is usually more developed
than the left. If these examples are not enough, a host of others
might be cited; such as, the atrabiliary capsules, the bladder, the
different organs of generation and lactation, and the very regular
arrangement of the mucous follicles in certain parts situated upon
the median line, &c. As to the anomalies that are observed in the
distribution of the blood-vessels, they are also observed very
frequently, though in a less evident manner, in the distribution of
the nervous branches.
CHAPTER III.
GENERAL DIFFERENCE OF THE TWO LIVES WITH REGARD TO THE MODE OF
ACTION OF THEIR RESPECTIVE ORGANS.
Harmony is to the functions of the organs, what symmetry is to
their conformation; it supposes a perfect equality of force and
action, between their similar parts, just as symmetry indicates an
exact analogy of external form, and internal structure: indeed it
is a necessary consequence of symmetry, for two parts essentially
alike in structure, cannot much differ in their manner of action.
Hence we should be naturally led to the following conclusion,
namely, that harmony is the character of the animal, discordance
that of the organic functions. But on these points we must be more
particular.
I. _Of harmony of action in the animal life._
We have already observed, that the animal life arises from the
successive actions of the senses, the nerves, the brain, the
locomotive organs, and the voice. We shall now consider what
harmony of action is, in each of these great divisions.
The precision of our sensations appears to be the more complete
in proportion as there exists a resemblance between the two
impressions, of which they are each of them the assemblage. We see
inaccurately when one of the eyes is better formed, and stronger
than the other; when it conveys to the brain a clearer image than
its fellow does. It is to avoid this confusion that we shut one
eye, while the action of the other is increased by the application
of a lens, for at such time there can be no harmony of action in
the two organs; accordingly, we make use of one of them only in
order to avoid the discordance of the impression.--What a lens
applied to one eye only produces artificially, is exemplified in
a natural way by squinting.--We squint, says Buffon, because we
turn the weaker eye from the object on which the stronger is fixed;
for in so doing we avoid the confusion, which would arise from the
perception of two dissimilar images.
We know that many other causes may contribute to the production
of this effect, but we cannot doubt the reality of the reason
assigned. We know also, that in some animals each eye may act
without the assistance of the other, and that two different objects
may be transmitted at the same time by the two eyes of certain
other animals; but this circumstance, when the action of both the
organs is united upon a single object, should by no means prevent
a similarity in the two impressions. A single sensation is the
consequence of the combination; but in what way can such sensation
be formed with accuracy, if the same body at the same time be
pictured both in strong and weak colours on the one and the other
of the retinæ?
What we have said of the eye may be equally well applied to the
ear. If, of the two sensations which form a sound, the one be
received by a strong and well formed organ, the other by a weak
one, the impressions will be unequal; the brain also, because it
is differently affected by each, will be the seat of an imperfect
perception. Such conformation constitutes what is called an
incorrect or false ear. For what reason does it happen that one
man is unpleasantly affected by a dissonance, while another does
not even perceive it? The reason is this, that in the one, the
two perceptions of the same sound are identical; in the other,
dissimilar.[8] For the same reason a man with a correct ear will
combine his dancing with the cadence of the measure given him;
another without this similarity of organ will be as constantly at
variance in his motions with the orchestra.
Buffon has confined his observations on harmony of action, to the
organs of vision and hearing; we shall push our examination of it
farther.
In the sense of smelling, as well as in the other senses, we must
admit of two impressions; the one primitive, and belonging to the
organ, the other consecutive, and affecting the sensorium: now the
latter may vary, the former remaining unaltered. Many odours are
disagreeable to some, but pleasant to others; and this, not because
there is any difference in the affection of the pituitary membrane,
but because in different individuals, the mind may attach a very
different sentiment to the same impression.--Hence a variety of
results does not in this case suppose a difference of principle.
But sometimes the impression which is made upon the pituitary
membrane does really differ from that which it ought to be, for
producing perfect sensation. Two dogs pursue the same game; the one
never loses scent, but makes the same turnings and windings with
the animal before him; the other follows his game also, but often
stops and hesitates, endeavors to recover the scent, proceeds and
stops again. The first of these receives a lively impression of the
scented emanation; the organs of the second are only confusedly
affected. Now it may be asked whether this confusion does not
arise from the unequal action of the two nostrils, from the
superior organization of the one, and from the imperfection of the
other?--the following observations appear to decide the question.
In the coryza, which affects but one of the nostrils, if the two
be suffered to remain open, the sense of smelling is confused; but
let the diseased nostril be shut, and the smell shall immediately
become distinct. A polypus in one of the nostrils debilitates the
action of the pituitary membrane on the affected side, the other
remaining in its healthy state: hence, as in the preceding case,
ensues a want of harmony in the two organs, and the same confusion
in the perception of odours. The greater number of the affections
of a single nostril have similar effects, which may be all of them
corrected by the same means. And wherefore? because in rendering
one of the pituitary membranes inactive, we put a stop to the
discordance which is occasioned by the deficiency of action in the
other. From the above facts (since any accidental cause, which
destroys the harmony of action in these organs, is capable of
rendering the perception of odours inexact) we may conclude, that
when the perception is naturally inaccurate, there is a natural
dissimilarity in the formation of the organs, and therefore a
difference of power in them.
The same reasoning may be applied to the sense of taste. It is
often the case that one side of the tongue is affected by palsy
or spasm, the median line dividing the insensible half from the
other, which continues to preserve its sensibility. But such
affection may take place in a variety of degrees, and one side of
the tongue retain a power of perceiving savours though in a less
perfection than the other side. In such case it is natural to
suppose that the taste must be confused; because a clear perception
cannot be the consequence of two unequal sensations.
The perfection of the touch as well as that of the other senses,
is essentially connected with uniformity of action in the two
symmetrical halves of the body, and particularly in the hands. Let
us suppose, for instance, a man born blind, to have one hand well
organized, the other defective in the power of moving the thumb
and fingers, and forming only a stiff and immovable surface; such
person would find it a very difficult thing to acquire a just
notion of the size and figure of bodies, because the same sensation
would not arise from the successive application of each hand to the
same substance. Let both of his hands, for example, be supposed to
touch a small sphere; the one by the extremities of the fingers
will embrace it in all its diameters, and convey to him the idea
of roundness; the other, which will be in contact with it only in
a few points, will produce a very different sensation. Embarrassed
between these two bases of his judgment, he will scarcely be able
to decide, nay, it is even possible that he may form a double
judgment from the double sensation which is presented him: his
ideas would be more correct were he to use only the perfect hand,
in the same manner as the person who squints, makes use of the
perfect eye only. Our hands then assist each other reciprocally;
the one confirms the notions which are given us by the other; hence
the necessary uniformity of their conformation.
The hands are not the only instruments of the sense of touch. The
axilla, the groin, the concavity of the foot and many other parts,
may all of them from their application to bodies, afford us so many
bases for our judgments with regard to external form. Now, if one
half of the body were differently arranged from the other half,
the same uncertainty in perception would infallibly be the result.
From all that has been said, we may conclude, that in the external
organs of sense, a harmony of action in the two symmetrical parts,
or the two similar halves of the organ, is a condition essential to
the perfection of sensation.
The external senses are the natural excitants of the brain. The
functions of the brain succeed to theirs, and this organ would
but languish, were it not to find in them the principle of its
activity. From sensation follow perception, memory and imagination;
from these the judgment. Now it is easy to prove, that these
different functions, commonly known by the name of the internal
senses,[9] are governed in their actions by the same laws, which
influence the external senses; and that like them, they approach
the nearer to perfection in proportion to the degree of harmony
existing in the symmetrical parts, in which they have their seat.
Let us suppose for instance one hemisphere of the brain to be
better organised, and therefore susceptible of livelier affections
than its fellow; in such case the perception of the individual
would be confused, for the brain is to the soul what the senses are
to the brain; it transmits to the soul the impressions conveyed to
it by the senses, as the senses convey to the brain the impressions
made upon them by external objects. But, if the defect of harmony
in the external senses confuse the perception of the brain, why may
not the soul perceive but confusedly, when the two hemispheres of
the brain are unequal in power, and incapable of blending into one
the double impression, which is made upon them?
The memory is the faculty of re-producing former sensations,
the imagination that of creating new ones, now in the act of
remembering or imagining, each hemisphere of the brain appears
to re-produce, or to create a sensation of its own. If both do
not act alike, the perception of the mind, which ought to be the
result of the two sensations united, will be inexact and irregular.
But, it is evident, that there will be a disparity in the two
sensations, if there be a disparity in the two halves of the brain,
in which they have arisen, and since the general foundations of
the judgment are made up of the faculties of perception, memory,
and imagination, if these be confused, the judgment itself must be
confused also.
We have now supposed an inequality of action in the hemispheres
of the brain, and inferred, that the functions would in this
supposition be imperfect; but what as yet is only supposition, in
a variety of instances can be proved to be a fact; for nothing is
more common than to find in consequence of compression on either
hemisphere by blood, pus, or exostosis, a variety of alterations in
the intellectual functions.
Even when all appearances of actual compression have vanished,
if in consequence of that which has been experienced, a part of
the brain remain enfeebled, the same alterations of mental power
will be found to be prolonged. If both hemispheres of the brain,
however, be affected equally, the judgment though weaker, will be
more exact.[10] Perhaps it is thus, that we should explain those
observations so frequently repeated, of an accidental stroke upon
one side of the head having restored the intellectual functions,
which had long remained dormant in consequence of a blow received
upon the other side.
I now conceive myself to have proved, that with inequality of
action in the hemispheres, there must be confusion of intellect.
I have also pointed out some states of disease, in which such
confusion is evidently the effect of inequality of action so
occasioned; here we see the effect and its cause; but may we not
from analogy, infer a similar cause where we see a like effect?
when the judgment is habitually incorrect, and all the ideas
wanting in precision, may we not be induced to believe, that there
does exist a defect of harmony in the action of the two hemispheres
of the brain? We see inaccurately if nature have not given to both
eyes an equal power; we perceive and judge inaccurately in like
manner, if the two sides of the brain are naturally dissimilar. The
most correct mind, and the soundest judgment, pre-suppose in the
hemispheres a perfect harmony of action; and what a multiplicity of
shades do we not behold in the operations of the understanding? it
is probable that they all of them correspond to so many varieties
in the proportions of power in the hemispheres. Could we squint
with the brain as we do with the eyes--that is to say, could we
receive impressions on one hemisphere only, and form from thence
our determinations, we might then command at will, a precision in
our intellectual operations; but such a power does not exist.
To the functions of the brain succeed those of locomotion and the
voice. The first of these would appear almost to form an exception
to the general law. In considering the two vertical halves of the
body, we shall perceive that the one is constantly more powerful
than the other with respect to the strength and number of its
movements. The right half is that, which from custom, is most made
use of.
To comprehend the reason of this difference; we must make a
difference between strength and agility; strength depends upon the
perfection of the organization, on the energy of the nutritive
process, on the plenitude of life in the muscular fibre; agility,
on the contrary, is the result of habit and frequent exercise.[11]
At present we shall observe, that this disparity of action in the
locomotive organs, does not consist in the difference of their
actual strength, but in that of the agility, with which these
motions are executed.--All is equal in the size, in the number of
fibres, and nerves both of the one and the other of the superior,
or inferior extremities; the difference of their vascular systems
is scarcely any thing. From hence it follows that the discordance
does not exist in nature, but that it is the effect of our social
habits, which by multiplying our movements on one side of the
body, increase their address without much adding to their power.
Such in fact are the wants of society, as to call forth a certain
number of general movements, which must be performed by all in the
same direction, in order to be understood. It is generally agreed,
that this direction shall be from left to right. The letters,
which form the writing of most nations, are in this way directed;
such circumstance occasions the necessity of our using the right
hand to form them in preference to the left, the former being as
much better adapted to this method, as the latter would be to the
contrary one; of this we may convince ourselves by experiment.
The direction of the letters from left to right, imposes on us the
necessity also of casting our eyes upon them in the same direction.
From this habit acquired in reading, arises that of examining
objects in the same manner.
The necessity of similar movements when men are drawn up in line of
battle, has induced almost all nations to handle their weapons with
their right hands; the harmony too which prevails in the dances of
even the most savage people exacts an accord in the limbs, which
they constantly preserve by making all their principal movements
with the right. We might add to these examples a great variety of
others.
The general movements agreed on by society, which, if every one
were not to execute them in the same direction, would be creative
of much confusion; these movements, I say, by the influence of
habit, oblige us for our own particular movements to use the limbs,
which they have brought into action. Hence, the members of the
right side of the body are perpetually in action either for our own
particular wants, or for those which we feel in conjunction with
others.
Now, as the habitude of acting, continually tends to the perfection
of action, we may perceive the reason, why the right side acquires
a greater facility in the performance of many motions than the
left. This increased facility is not original, but acquired.
So remarkable a difference then, in the two symmetrical halves of
the body, is not by nature meant as an exception to the general
law of harmony of action in the external functions; for those
movements, which are executed by the whole of the body, are the
more precise in proportion to the smallness of the difference
existing in the agility of the muscles of the two sides. How
happens it that certain animals leap from rock to rock with such
admirable precision, where the least deviation from the intended
direction, would plunge them into an abyss? how happens it that
they run with such astonishing address on planes, which are
scarcely equal in breadth to the extremities of their limbs? how
happens it that the walk of the very heaviest of animals is never
attended with those false steps so frequent in the progression of
man? The reason must be, that the difference in their locomotive
organs in both sides of the body is scarcely any thing, and that
in consequence there must be a constant harmony of action in these
organs.
He, whose general movements, or those of the whole of the body are
the most perfect, has the least command in particular over those of
the right side; for, as I shall prove hereafter, the perfection of
a part is never acquired but at the expense of that of the whole.
The child, who should be taught to make an equal use of all his
limbs, would possess a precision in his general movements, which he
would find extremely difficult to acquire for those of the right
hand, such as writing or fencing.
I can easily suppose, that some few natural circumstances may have
exercised upon us an influence in our choice with respect to the
direction of those general motions, which the habits of society
have established. Such may be the slight excess of diameter in the
right subclavian artery, and the sensation of lassitude during
digestion, which is more perceived upon the left side on account
of the situation of the stomach, and may therefore have determined
us to act at such time upon the opposite side in preference. Such
also may be the natural instinct, by which, to express our feelings
we carry the right hand to the heart; but these circumstances
are trifling in comparison with the very great difference of the
movements which from the state of civilization exists between the
symmetrical halves of the body; and from this view of the subject,
we cannot but regard this difference as the effect of social
convention, and by no means the intent of nature.
The voice, together with locomotion, is the last act of the animal
life in the natural order of its functions. Now the greater number
of physiologists, and Haller in particular, have indicated as the
causes of want of harmony in the voice, the dissimilarity of the
two portions of the larynx, the inequality of force in the muscles,
which move the arytenoid cartilages, the same inequality of action
in the nerves, which are distributed to each half of the organ,
and the different reflection of sounds in the nostrils and frontal
sinuses. Without doubt a defective voice must frequently depend
upon a faulty ear; when we hear incorrectly, we sing incorrectly;
but when a correct ear is united with a want of precision in the
voice, the cause is then in the larynx.
The most harmonious voice is that, which the two portions of the
larynx produce in an equal degree; where the vibrations on one side
correspond exactly in number, strength and duration with those upon
the opposite side.[12] In the same manner the most perfect singing
will be produced by two voices exactly similar in tone, compass,
and inflection.
From the numerous considerations which I have offered, the
following general conclusion may be deduced--namely, that one
of the most essential characteristics of the animal life, is a
harmony of action in the two analogous parts, or in the two sides
of the simple organ concurring to the same end. The relation which
exists between this harmony of action, which is the character of
the functions, and symmetry of form, which is the attribute of the
organs of the animal life, will easily be seen.
I wish to observe in finishing this section, that in pointing out
the different derangements, which take place in the animal life,
from the want of harmony in the organs, I have only pretended to
assign a single isolated cause of such derangements; I am well
aware that a thousand other causes besides dissimilarity in the
hemispheres of the brain, may affect the operations of the mind.
II. _Of discordance of action in the organic life._
Along with the phenomena of the animal life, let us now consider
those of the organic life, and we shall find that harmony has
nothing to do with them. Of what detriment would it be to the
general health of the individual, should one of his kidneys be
stronger than the other, and secrete more urine; should one of his
lungs be better unfolded than the other, admit more venous, and
send out more arterial blood; should a less organic force be the
lot of the salivary glands on one side than on the other side of
his body? The simple function, to which both organs concur, would
not be performed less perfectly. Whenever but a slight fulness
supervenes on one side of the liver, spleen, or pancreas, the sound
part makes up for the defect, and the function is little disturbed.
The circulation also remains unaltered among the frequent
variations in the vascular system of each side of the body, whether
such variations exist naturally, or whether they arise from some
artificial obliteration of the larger vessels as in aneurism.
Hence we find those numerous irregularities of structure, those
malconformations, which as I have said may be remarked in the
organic life, and nothing of a morbid nature in consequence
arising. From hence we see that almost continual succession of
modifications, which lessen or increase the circle of the organic
functions. The vital powers, and their exciting causes, are
continually varying, and thus occasion a constant instability in
the functions of the organs, for a thousand causes may at every
moment double or triple the activity of the circulation, and
respiration, increase or diminish the quantity of bile, urine, or
saliva, and suspend or augment the nutrition of the parts. Hunger,
food, sleep, motion, rest, and the passions may all of them impress
upon these functions so great a mobility, as every day to make them
run through a hundred degrees of strength or weakness.
In the animal life on the contrary, every thing is uniform and
constant, the powers of the senses cannot experience these
alternate modifications, or at least, not in so marked a manner.
Indeed they are at all times in a state of relation with the
physical powers, which preside over exterior bodies; now the latter
remaining unaltered, such variations would destroy all relative
connexion, and thus the functions cease.
Besides, if this mobility, which characterises the organic life,
were the attribute of sensation--for the same reason it would be
that of all the operations of the mind. In such case of what would
man consist? The perpetual sport of every thing surrounding him, he
would find his existence at one time little different from that of
inanimate matter, at others superior in perfection and energy to
that even which he now enjoys, allied at one time to the brute, at
another, to spiritual nature.
FOOTNOTES:
[8] This supposition, though no doubt ingenious, is not true. If
the want of accuracy of hearing arose in fact from the inequality
of the power of the two organs, this defect might be remedied by
using but one ear; but experience gives a different result. We
shall not discuss, in relation to the same principle of inequality
of the organs, the explanation of strabismus; but at least, for
every thing that relates to the just appreciation of colours, this
principle is no more applicable than to the just appreciation of
sounds. I know a man who has never been able to distinguish the
_blue of the sky_ from _the green of the sea_, and he succeeds no
better by closing one eye.
[9] We cannot, without confounding all the ideas we have formed of
the senses, give this name to the memory, imagination and judgment;
at the most we might give the name of internal senses to certain
sensations which inform us of the particular state of some internal
organ, in the same way as the external senses make us acquainted
with the properties and state of external bodies.
[10] We cannot conceive how the judgment can be weak or strong,
if we do not understand by it that it is habitually accurate or
inaccurate. His judgment is sound who usually perceives the true
relations between things; and this is independent of the number and
variety of the ideas upon which he has to pronounce. The man to
whose mind there is presented but a small number of relations, has
but little imagination; but if these relations be true, we cannot
say that his judgment is weak.
[11] Bichat, in order to retain for the organs of organic life
the character of irregularity in the forms which he had assigned
to them, has been compelled to avail himself of the inequality
of the size of the congenerous organs. He soon repented having
established an uniform principle; and in this case for example,
he is near being condemned by the very sentence which he has
himself pronounced. The locomotive system, in fact, the symmetry of
which no person before him thought of denying, is destitute of it
according to the principle he has established, since it presents in
its two halves an inequality of size and action. In order to avoid
this consequence, Bichat has maintained that the inequality of size
arose from the inequality of action, and that this was the result,
not of an original disposition, but of our social habits only. To
prove this assertion, he has been compelled to heap sophism on
sophism; he cannot in this case be suspected of a wish to deceive;
he was convinced of the truth of the principle, and we know that
to prove what is believed to be true, the weakest reasons always
seem to be sufficient. But these very errors should be turned to
our advantage, by showing us how dangerous is the tendency of
generalizing upon every thing, since it was capable of misleading
so judicious a mind.
Without stopping to refute in detail all the reasons which he has
advanced to support his opinion, we cannot help saying something
of them; and in the first place, the difference of size uniformly
exists; it is evident that it does not arise from great exercise,
since it is found in the infant at birth, and the nourishing artery
of the right arm is larger than that of the left. If the right
arm be not really stronger than the other, why should we always
use it in preference? If we employ it in writing, should we say
with Bichat, that it is only because it is better situated to
move from left to right, in the order in which the characters of
our writing succeed each other; might it not be said, with more
reason, that our letters go from left to right, because it is the
direction in which the right hand most easily traces them? All this
besides relates merely to the form of our characters, since all the
oriental languages are written from right to left; yet it is always
done with the right hand. Is it still said that the necessity of
union in battle has led to the employment of the right arm to hold
the weapons, as if the Hurons or Algonquins fought in close ranks
like our Grenadiers. If this use of the same arm or the same leg
was only conventional, why among some people, is the left side
never preferred?
[12] The theory of wind instruments is not yet sufficiently well
understood, to enable us to say, what sort of influence would be
exerted upon the sound by the inequality of vibrating plates.
(See the article Voice, in my Elements of Physiology, Vol. 2d.)
CHAPTER IV.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO DURATION OF
ACTION.
One of the great distinguishing characters of the phenomena of
the animal life in opposition to those of the organic life, has
just been shewn. That, which I am about to examine, is not of
less importance. The functions of the animal life intermit; the
functions of the organic life are performed with an uninterrupted
continuity.
I. _Of continuity of action in the organic life._
Prolong but little the causes which are capable of suspending
respiration, or the circulation of the blood, and life itself
shall be suspended, nay, even annihilated. All the secretions go
on uninterruptedly; if they intermit at all (and those of the bile
and saliva for instance, when not immediately required for the
purposes of digestion and mastication, may be said to intermit)
such intermissions affect the intensity of the secretion only, and
not the entire exercise of the function. Exhalation and absorption
incessantly succeed each other; the process of nutrition must be
continually carried on; the double movement of assimilation and
decomposition from which it results, can only be terminated with
life itself.
In this concatenation of the organic phenomena, each function
depends immediately upon those which precede it. The centre of them
all, the circulation, is immediately connected with the exercise
of them all, for when this is troubled, they languish, when this
ceases, they cease also. Just in the same manner the movements of a
clock all stop with the pendulum. Nor only is the general action of
the organic life connected with the heart; but there cannot exist a
single function of this nature unconnected with all the others, for
without secretion, there can be no digestion, without exhalation
no absorption, without digestion no nutrition. Hence as a general
character of the organic functions may be indicated continuity of
action, and mutual dependence.
II. _Of intermission of action in the organic life._
In the exercise of the functions of the animal life, there will
be regularly seen an alternation of activity and repose, complete
intermissions, and not remissions only.
Fatigued by long continued action, the senses all alike become
for a time, incapable of receiving any further impression. The
ear loses its sensibility to sound, the eye to light, the tongue
to savours, the pituitary membrane to smells, the touch to the
qualities of bodies about which it is conversant, and all this for
the sole reason that the respective functions of these different
organs, have for a long time been exercised.
In like manner, the brain fatigued by too great an effort in
the exercise of any of its powers, in order to regain its
excitability, must cease to act for a period proportioned to the
duration of its preceding action. The muscles also after having
been strongly contracted, before they can contract anew, must
remain for awhile in a state of relaxation. Hence in locomotion,
and the exertion of the voice, there must be intermissions.
Such then is the character peculiar to the organs of the animal
life. They cease to act because they have acted. They become
fatigued, their exhausted powers must be renewed.
This intermission is sometimes general, sometimes partial. When
a single organ, for a long time has been exercised, the others
remaining inactive, it relaxes and sleeps, the others continuing
to watch.--Hence, without doubt, proceeds the reason, why there is
no immediate dependence among the functions of this order on each
other. The senses being shut up against sensation, the brain may
still subsist in action, may remember, imagine, or reflect. In such
case the power of locomotion and the voice also, may equally well
be exercised, and these in like manner may remain unexercised, and
the activity of the senses be in no-wise impaired.
Thus the animal at will may fatigue any one of the parts of this
life, and on this very account, such parts must all of them possess
a capability of being relaxed, a power of repairing their forces in
an isolated manner. This is the partial sleep of the organs.
III. _Application of the law of intermission of action to the
theory of sleep._
General sleep is the sleep of all the parts. It follows from that
law, which with respect to the functions of the animal life,
enchains intermission with periods of action, from that law, by
which this life is particularly distinguished from the organic life.
Very numerous varieties are remarked in this periodical state, to
which all animals are subject. The most complete sleep is that in
which the outward life is entirely suspended. The least perfect
sleep is that which affects one organ only; it is that of which we
have just been speaking.
Between these two extremes there are many intermediate states. At
times perception, locomotion, and the voice only are suspended;
the imagination, the memory, and the judgment remaining in action.
At other times, to the exercise of the latter faculties are added
those of the locomotive organs and the voice.--Such is the sleep,
in which we dream, for dreams are nothing more than a portion of
the animal life escaped from the torpor, in which the other portion
of it is plunged.
Sometimes but very few of the senses have ceased their
communication with external objects. Such is that species of
somnambulism, in which to the action of the brain, the muscles, and
the larynx, are added the very distinct actions of the ear and the
sense of touch.[13]
Sleep then cannot be considered as a constant and invariable state
with regard to its phenomena.--Scarcely ever do we sleep in the
same manner twice together. A number of causes modify in applying
to a greater or less portion of the animal life the laws of
intermission of action. Its different degrees should be marked by
the different functions, which these intermissions affect.
But the principle of it is every where the same from the simple
relaxation of a muscle to the entire suspension of the whole of the
animal life. Its application, however, to the different external
functions, varies without end.
These ideas on sleep are different, no doubt, from that narrow
system, where its cause exclusively placed in the brain, in the
heart, in the large vessels, or in the stomach, presents an
isolated and frequently an illusory phenomenon, as the base of one
of the great modifications of life.
And what is the reason why light and darkness in the natural order
of things, coincide so regularly with the activity or intermission
of the external functions? The reason is this, that during the day
a thousand means of excitement perpetually surround the animal, a
thousand causes exhaust the powers of his sensitive and locomotive
organs, fatigue them, and prepare them for a state of relaxation,
which at night is favoured by the absence of every kind of
stimulus. Thus, in the actual state of society, where this order
is in part inverted, we assemble about us at evening, a variety
of excitants, which prolong our waking moments, and put off until
towards the first hours of daylight, the intermission of our animal
life, an intermission, which we favour besides by removing from the
place of our repose whatever might produce sensation.
We may for a certain time, by multiplying the causes of excitement
about them, withdraw the organs of the animal life from this law of
intermission, which should naturally cause them to sleep; but at
last they must undergo its influence, and nothing can any longer
suspend it. Exhausted by watching, the soldier slumbers at the
cannon’s side, the slave under the whip, the criminal in the midst
of torture.
We must carefully make a distinction, however, between the
natural sleep, which is the effect of lassitude, and that, which
is the consequence of some affection of the brain, of apoplexy,
or concussion, for instance. In the latter case the senses
watch, receive impressions, and are affected as usual, but these
impressions are not perceived by the diseased sensorium; we cannot
be conscious of them. On the contrary, in ordinary sleep the senses
are affected as much, or even more than the brain.
From what has now been said, it follows, that the organic life,
has a longer duration than the animal life. In fact the sum of the
periods of the intermissions of the latter, is almost equal to that
of the times of its activity. We live internally almost double the
time that we exist externally.
FOOTNOTE:
[13] The action of the brain is far from being preserved in
somnambulism. The thread of ideas, on the contrary, is completely
broken, and this is the most striking character which distinguishes
every kind of sleep from wakefulness. The mind then cannot
reflect upon the sensations which it receives, it abandons itself
successively and without any resistance to all those which are
presented, without examining the connexion which they can have
between them. In ordinary sleep, the senses are almost entirely
blunted, the mind receives no other sensations than those which
have been derived from memory; but they present themselves in a
confused manner, without order and in such a way as often to form
the most strange and incoherent images. In somnambulism the action
of many senses, and that of hearing in particular is preserved; the
judgment of the sleeper can then exercise itself not only upon its
reminiscences, but also upon the impressions which are transmitted
to it from without. The sound of a bell or a drum, being heard
while we are in a dream, will immediately modify it. In this way a
person may gain the attention of a somnambulist, and as the latter
possesses the use of his voice, it will be seen by his answers that
his ideas can be directed at will, and led in this way wherever it
is wished; for the impressions that he receives from without, being
stronger than those which come from memory, he will almost always
obey the first.
CHAPTER V.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO HABIT.
Another of the great distinguishing characters of the two lives of
the animal, consists in the independence of the one, and in the
dependence of the other on habit.
I. _Of habit in the animal life._
In the animal life every thing is modified by habit. The functions
of this life, whether enfeebled or exhausted by it, according
to the different periods of their activity, appear to assume a
variety of characters: to estimate the influence of habit, it is
necessary to consider two things in the effect of all sensation,
the sentiment, or immediate feeling, which we have of external
objects, and the judgment which is the result of one or more
comparisons made with respect to them. An air, for instance,
strikes the ear; the first impression made upon the organ is, we
know not why, agreeable or painful. This is sentiment--at present
let us suppose the air to be continued. We may now endeavour to
appreciate the different sounds of which it is composed, and to
distinguish their accords. In this we exercise the judgment. Now,
on these two things, the action of habit is inverse. It enfeebles
our sentiment of things, it improves our judgment of them; the more
we regard an object, the less are we sensible of its agreeable or
painful qualities, the better, at the same time, may we judge of
its attributes.
II. _Habit blunts the sentiment._
Let us dwell a little on the foregoing proposition; we have said
that it is the property of habit to enfeeble our sentiments of
things, to bring us into a state of indifference, the middle
term betwixt pain and pleasure. But before we set about to prove
an assertion so remarkable, it will be well to fix the sense
of it with some precision. Pain and pleasure are absolute and
relative.[14] The instrument which tears us in pieces is a cause of
absolute pain. Sexual connexion is a pleasure of the same nature.
Again, the view of a beautiful country delights us, but here the
enjoyment is relative to the actual state of the mind only; its
charms have long since been indifferent to the inhabitant of the
spot. A bougie when for the first time passed into the urethra is
painful to the patient; eight days afterwards he is no longer
sensible of it. Here we have comparative pain. Whatever destroys
the texture of the organ is always productive of an absolute
sensation; the simple contact of bodies at no time produces any
other than a relative sensation.
Hence it is evident that the domain of absolute pleasure or pain,
is much less extensive than that of these feelings when relative.
The very words agreeable, or painful, imply a comparison made
between the impression received by the senses, and the state of
mind on which it is received. Now it is manifest that we could have
referred only to relative pain and pleasure, as being submitted to
the influence of habit. On these we shall occupy ourselves awhile.
And to shew that they are gradually worn away by habit as we have
said, to the point of indifference, a variety of proofs may be
adduced. Every foreign body in contact for the first time, with a
mucous membrane, is creative of a disagreeable sensation, which
by repetition, is diminished, and at last becomes altogether
imperceptible. Pessaries in the vagina, tents in the rectum, the
canula made use of for tying polypi of the nose, or the uterus,
bougies, in the urethra, in the œsophagus, or trachea, styles and
setons in the lachrymal passages, present us every day with these
phenomena. The impressions of which the cutaneous organ is the
seat, are all of them subjected to the same law. The sudden passage
from cold to heat, or from heat to cold, is always the occasion of
a disagreeable sensation, but such sensation gradually and at last
entirely disappears, if the temperature of the atmosphere be within
a certain range and constant. From hence proceed those various
sensations, which we have from the change of climate, or season.
Similar phenomena in the same way are the result of our successive
perceptions of the dry or humid, the soft, or the hard qualities
of bodies, and in general the same may be said of all our relative
sensations, of what kind soever.
With respect to pleasure, we shall repeat what we have said of
pain. The perfumer and the cook are by no means sensible in their
several professions of those pungent enjoyments of which they
are dispensers. In them the habit of perceiving has blunted the
sentiment. The same is the case with all agreeable sensations
whatever. Delightful views and delicious music are productive of a
pleasure, the vivacity of which is soon lessened; for harmony and
beauty if they for a long time continue to solicit our attention,
are successively the sources of pleasure, of indifference, of
satiety, nay even of disgust and aversion. This remark has been
felt by all; Philosophers and Poets have all of them turned it to
their account.
From whence arises this facility, which our sensations have of
undergoing so many different, so many contrary modifications?
To conceive it, let us first remark that the centre of these
revolutions of pleasure, of pain, and of indifference, is by
no means seated in the organs, which receive or transmit the
sensation, but in the soul. The affections of the eye, of the
tongue, and the ear, are at all times the same from the same
objects, but to these affections at different times, we attach
a variety of sentiments. In the second place we shall observe,
that the action of the mind in each several sentiment of pain or
pleasure, which has been the effect of a sensation, consists in a
comparison between this sensation, and that by which it has been
preceded, a comparison, which is not the result of reflection,
but the involuntary effect of the first impression of the object.
Now, the greater the difference between the actual and the past
impression, the livelier will be the sentiment. The sensations
which affect us the most, are those which we never before have
experienced.
The consequence is, that in proportion as the same sensations
are repeated, the less impression do they make upon us, because
the comparison between the present and the past becomes less
sensible. Pain then and pleasure naturally tend to their own
annihilation. The art of prolonging our enjoyments, consists in
varying their causes. Indeed were I to regard the laws of our
material organization only, I might almost say, that constancy
is but one of the happy dreams of the poet, and that the sex to
which we at present bend, would possess but a very weak hold upon
our attentions were their charms too uniform; I might almost
assert that were every female cast in the same mould, such mould
would be the tomb of love. But here let us forbear to insist upon
the principles of physiology, where they tend to the destruction
of those of morality. The one, and the other are equally solid,
though sometimes at variance. We shall only notice, that at times
the former unhappily are our only guides. It is then, that love
disappears, with the pleasure which it has procured, and leaves
us but disgust. It is then, that recollection too often carries
us aside from our duties in rendering uniform that which we feel
and that which we have felt, for such appears to be the essence of
physical happiness, that past pleasure enfeebles the attraction of
that which we enjoy.
The consequences are clear. Physical pleasure is nothing but
a comparative sentiment; it ceases to exist when uniformity
supervenes between the actual and past impression. By means of this
uniformity habit must bring down pleasure to indifference: Such is
the secret of the very great influence which it exercises over our
enjoyments.
Such also is its mode of action on our pains. Time flies, it
is said, and carries away sorrow; time is the true remedy of
grief; and wherefore? The reason is, that the more sensations it
accumulates upon that which has been painful, the more does it
enfeeble the sentiment of comparison between what we are, and what
we were. At last this sentiment becomes extinct. There are no
eternal sorrows.
III. _Habit improves the judgment._
I have just now proved that the sentiment is enfeebled by the
effect of habit. It is as easy to demonstrate, that habit improves
and enlarges the judgment.
When, for the first time, the eye wanders over an extensive
country, or the ear is struck by a succession of harmonious
proportions; when the taste, or the smell for the first time are
affected by any very compound savour or scent, there arise from
these sensations only confused and inexact ideas. We represent to
ourselves the whole, its parts escape us. But let these sensations
be repeated, and in proportion as they are so, will the judgment
become precise and rigorous, and the knowledge of the object be
perfected.
Let us for instance observe the man, who a stranger to theatrical
amusement of every kind is introduced to the Opera. He will
have but a very imperfect notion of it. The dancing, the music,
the scenery, the actors, the splendor of the whole will be all
confounded within his mind in a sort of delightful chaos. But
let him be present at many representations, and whatever in this
charming whole belongs to the several arts, will assume its
separate place. He will have seized its detail, may form a judgment
of it, and this he will do the more accurately in proportion to his
opportunities of observation.
The above example affords us an abridgment of the picture of the
man, who enjoys for the first time the spectacle of nature. The
child, at its birth, is only capable of general impressions, but
habitude, by gradually blunting these impressions, enables him
to seize the particular attributes of bodies, and teaches him to
see, to hear, to smell, to taste and to touch, by making him in
each sensation descend successively from the confused notion of
the whole to the precise idea of its parts. The animal life needs
education, and this is one of its great characters.
Habit then while it hebetates our sentiments, improves our
judgments of things. An example will render this truth
indisputable. Most persons may recollect that in traversing a
meadow, embellished with a variety of flowers, they have been
sensible of a general fragrance only, the confused assemblage of
all the particular odours which are exhaled from each individual
flower; but in a short time from habit this first sentiment is
weakened, it is soon afterwards altogether effaced. They then may
have distinguished the odour of each particular plant, and formed a
judgment at first impossible.
The two contrary operations thus of habit on our sentiments and
judgments, tend as we see to one common end, the improvement,
namely, of the animal life.
IV. _Of habit in the organic life._
Let us at present compare the above-mentioned phenomena with those
of the organic life, and the latter we shall see as constantly
withdrawn from the influence of habit, as the former are subject to
it.--Habit has never modified the circulation, or respiration, has
never changed the mode of the processes of exhalation, absorption,
or nutrition. A thousand causes would every day endanger our very
existence, were these essential functions under the influence of
habit.
The excretion of the urine and fecal matter may, nevertheless, be
suspended, accelerated, and return according to laws determined by
habit. The action of the stomach with respect to hunger, and its
contact with certain aliments, appears also to be subordinate to
habit; but here let us remark, that these different phenomena hold,
as it were, a middle place between the two lives, are found on the
limits of the one and the other, and participate almost as much
of the animal as the organic life. In fact, they all of them take
place on mucous membranes, a species of organ, which being at all
times in relation with bodies foreign to our nature, is the seat of
an inward tact, in every way analogous to the outward tact of the
skin. The two must be necessarily subject to the same laws.--Can we
be astonished at the influence of habit on both of them?
We cannot, and let us remark also, that the greater part of these
phenomena, which begin as it were, and terminate the organic
life, are connected with motions essentially voluntary, and in
consequence, under the dominion of the animal life.
I shall not here enlarge on the numerous modifications of power,
taste, and desire, which have their source in habit. I refer to the
numerous works which have considered its influence in a different
point of view from that which I have indicated.
FOOTNOTE:
[14] Pleasure and pain are always absolute sensations, but they
may depend upon relative circumstances; that degree of cold, for
example, does not incommode the inhabitant of Spitzbergen, which
would be very painful to a man from a temperate climate. In order
to understand how habit produces these effects, we must recollect
that the repetition of the same sensations on the same part
exhausts at length the sensibility of it. Hence we may conceive
how the contact of a body upon a living surface may cease to be
painful, while any division or solution of continuity of one of
our organs will be always more or less so, because the nerves that
are divided are unaccustomed to this sensation, and still possess
their whole sensibility. The sense of sight furnishes us with a
striking example of sensibility being exhausted by the continuation
of the sensation; if we look for a long time with the same eye upon
a white surface with a red spot in the middle of it, and then look
upon a part that is all white, we shall perceive there a greenish
spot; for the part of the retina which has been a long time in
contact with the red rays, loses the peculiar sensibility that
enables it to transmit this sensation perfectly; and of all the
coloured rays which compose the white rays that now go to it, it
transmits only those to which it is unacquainted; hence results the
sensation of green.
CHAPTER VI.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO MENTAL
AFFECTION.
It is necessary to consider, under two relations, those acts, which
little connected with the material organization of animals, are
derived from this principle so little known in its nature, but so
remarkable as to its effects, the centre of all their voluntary
motions, and on the subject of which, there would have been less
dispute, if philosophers, instead of attempting to reach its
essence, had been contented with analyzing its operations. These
actions, which we shall consider more especially in man, with
whom they are the most perfect, are either purely intellectual,
and relative to the understanding only; or they are the immediate
product of the passions. Examined under the first point of view,
they are the exclusive attribute of the animal, under the second of
the organic life.
I. _Whatever relates to the understanding belongs to the animal
life._
It would be useless for me to insist on proving that meditation,
reflection, the judgment, and all the operations of the mind
depending upon an association of ideas are under the dominion of
the animal life. We judge from impressions formerly or actually
received, or from those which we ourselves create. Perception,
memory, and the imagination are the principal bases, on which are
founded the operations of the mind, but these very bases themselves
repose upon the action of the senses.
Let us suppose a man at his birth to be deprived of all that
exterior apparatus, which is destined to establish his connexions
with surrounding objects; such man will not altogether be the
statue of Condillac, because, as we shall see hereafter, other
causes besides the sensations, may occasion within him the motions
of the animal life; but at least will he not be able, a stranger
as he is to every thing surrounding him, to form any judgment with
respect to things. The intellectual functions with him will be
null; volition, which is the consequence of these functions, will
not have place, and consequently, that very extensive class of
motions which has its immediate seat in the brain, and which itself
is but an effect of the impressions made there, will in nowise
belong to him.
It is by means of the animal life that man is so great, so superior
to the beings, which surround him; by means of this that he
possesses the sciences, the arts, and every thing which places him
at a distance from the gross elements under which we represent
brute matter; by this that he approaches spirituality; for industry
and commerce, and whatever enlarges the narrow circle within which
the efforts of other animals are confined, are exclusively under
the dominion of the animal life of man.
The actual state of society then is nothing but a more regular
development, a more marked perfection of the exercise of the
different functions of this life; for one of its greatest
characters as I shall hereafter prove, consists in its capability
of being unfolded, while, in the organic life, there does not exist
a part, which in the least degree may pass the limits which are set
to it by nature. We live organically in as perfect, in as regular a
way, when infants, as when men; but what is the animal life of the
child compared with that of the man of thirty years of age?
We may conclude that the brain, the central organ of the animal
life, is the centre of whatever relates to the understanding. I
might here proceed to speak of its volume in man, and in animals,
whose intelligence appears to decrease in proportion as the facial
angle is diminished, and expatiate upon the different alterations
of which the cerebral cavity is the seat, as well as on the
disorders of the intellectual functions arising thence. But these
things are all of them well enough understood. Let us pass to that
order of phenomena, which though as foreign as the preceding to the
ideas which we form of material appearances, are elsewhere seated.
II. _Whatever relates to the passions belongs to the organic life._
My present object is not to consider the passions metaphysically.
It little matters, whether they be all of them the modifications
of a single passion, or dependent each of them upon a separate
principle. We shall only remark, that many physicians in discussing
their influence on the organic phenomena, have not sufficiently
distinguished them from the sensations; the latter are the occasion
of the passions, but differ from them widely.
It is true that anger, joy, and sorrow, would not affect us,
were we not to find their causes in our connexions with external
objects. It is true also, that the senses are the agents of these
relations, that they communicate the causes of the passions, but in
this they act as simple conductors only, and have nothing in common
with the affections, which they produce; for sensation of every
kind has its centre in the brain, sensation of every kind supposing
impression and perception. If the action of the brain be suspended,
sensation ceases; on the contrary, the brain is never affected by
the passions; their seat is in the organs of the internal life.[15]
It is undoubtedly surprising that the passions, essentially as they
enter into our relations with the beings which are placed about
us, that modifying as they do at every moment these relations,
that animating, enlarging, and exalting the phenomena of the
animal life, which without them would be nothing but a cold series
of intellectual movements; it is astonishing, I say, that the
passions should neither have their end, nor beginning in the organs
of this life, but on the contrary, that the parts which serve for
the internal functions, should be constantly affected by them, and
even occasion them according to the state in which they are found.
Such notwithstanding is the result of the strictest observation.
I shall first observe, that the effect of every kind of passion
is at all times to produce some change in the organic life. Anger
accelerates the circulation of the blood, it multiplies the efforts
of the heart. The passion of joy has not indeed so marked an
influence upon the circulation, but alters it notwithstanding, and
carries it lightly towards the skin. Terror acts inversely; this
passion being characterized by a feebleness in the vascular system,
a feebleness, which in hindering the blood from arriving at the
capillary vessels, occasions the paleness which at such time is so
particularly remarked. The effects of sadness and sorrow are nearly
analogous.
So great indeed is the effect which the passions occasion upon the
organs of the circulation, as even to arrest them altogether in
their functions, where the affection is very powerful. In this way
is syncope produced, for the primitive seat of syncope is always,
as I shall soon prove it to be, in the heart, and not in the brain.
In this the latter organ ceases to act, only because it ceases to
receive the excitant necessary to its action. Hence also may happen
death itself, the sometimes sudden effect of extreme emotion,
whether such emotion as in anger so far exalts and exhausts the
powers of the circulation, as not to leave them any further
excitability, or whether as in the death occasioned by excessive
grief, the powers at once excessively debilitated, are no longer
capable of returning to their usual condition.
If the total and instantaneous cessation of the circulation be not
occasioned by this debility, a variety of lesions in the blood
vessels may be, notwithstanding, the effect of it. Desault has
remarked that diseases of the heart, and aneurisms of the aorta,
were augmented in number during the revolution, in proportion to
the evils which it produced.
Nor does respiration depend less immediately upon the passions;
that oppression, that anxiety, and sense of suffocation, which is
the sudden effect of profound sorrow, must imply in the lungs a
remarkable change and sudden alteration. In that very long series
of chronic or acute affections, the sad attribute of the pulmonary
system, must we not often look to the passions to find the
principle of the disease?
And that lively sensation at the pylorus under strong emotion,
that ineffaceable impression which sometimes remains there, from
whence succeed the schirri of which it is the seat, that sentiment
of stricture, as it were, about the stomach, about the cordia in
particular; under other circumstances those spasmodic vomitings,
which sometimes follow the loss of a beloved object, the news of
a fatal accident, or any kind of trouble, the cause of which are
the passions; that sudden interruption of the digestive phenomena
either in consequence of agreeable or disagreeable news, those
affections of the bowels, those organic lesions of the intestines,
of the spleen observed in cases of melancholy, or hypochondria,
diseases which are always preceded by sad forebodings and the
darker affections of the mind; do not all these indicate the very
strict connexion of the digestive viscera with the state of the
passions?
They do; and the secreting organs have not a less connexion with
them. Sudden fear suspends the course of the bile, and is the
occasion of jaundice; sudden anger is often the origin of bilious
fever. In a state of sorrow or joy, sometimes even in that of
admiration, our tears flow abundantly: the pancreas is not less
frequently affected in hypochondria.
But the functions of the circulation, of digestion, respiration and
secretion, are those which are most directly under the influence
of the passions; those of exhalation, absorption and nutrition
appear to be less so. Doubtless, the reason of this is, that these
functions have not as the former any principal focus, or essential
viscera, the state of which may be compared with that of the mind.
Their phenomena disseminated throughout all the organs belong
exclusively to none, and cannot be observed as well as those, the
effects of which are confined within a narrow compass.
Nevertheless, the alterations, which these functions experience are
not less real, do not become less apparent after a certain time;
let the man, whose hours are marked by sorrow, be compared with
him, who lives in peace of mind, and the difference of the process
of nutrition in the one and in the other will easily be seen.
Let us, for a moment, approximate the times, when the terrible
passions of sorrow, of fear and revenge seemed to brood over our
country, and those, when safety and abundance continually supplied
us with the gayer ones so natural to us; we may then recall what
at the two periods were the outward appearances of our countrymen,
and appreciate the influence of the passions on the process of
nutrition. The very expressions which are continually in our mouths
that such a one is dried up with envy, preyed upon by remorse,
consumed and wasted away with sorrow, do not even these announce
how much the nutritive functions are modified by the passions?
I know not for what reason the powers of absorption and exhalation
should not be subject to the same influence, though they appear to
be less so; may not dropsies, and all infiltrations of the cellular
membrane, the peculiar vices of these two functions, depend on
mental affection?
In the midst of these disturbances, of these partial or general
revolutions which are produced by the passions in the organic
phenomena, let us consider the actions of the animal life;
they constantly remain unaltered, or if they do experience any
derangement, such derangement has ever its source in the internal
functions.
From so many considerations we may conclude that it is upon the
organic and not upon the animal life that the passions exercise
their influence. Accordingly, whatever serves to paint them must
relate to the former. Of this assertion, our gestures which are
the mute expressions both of the sentiment and understanding are a
remarkable proof. Thus if we indicate any operation of the memory,
imagination or judgment, the hand is carried to the head; do we
wish to express either love or hatred, or joy or sorrow, it is to
the seat of the heart, the stomach or intestines, that it is then
directed.
The actor, who should mistake in this respect, who in speaking of
sorrow should refer his gestures to his head, or carry them to his
heart, for the purpose of announcing an effort of genius, would be
ridiculed for a reason which we should better feel than comprehend.
The very language of the vulgar, at a time when the learned
referred to the brain, as the seat of the soul, affections of all
kinds, distinguished the respective attributes of the two lives.
We have always said a strong head, a head well organized to denote
perfection of mind; a good heart, a sensible heart, to indicate
proper feeling. The expressions of fury circulating in the veins,
and stirring up the bile; of joy making the heart leap, of
jealousy distilling its passions into the heart, are by no means
poetical expressions, but the enunciation of that which actually
takes place in nature. In this way do all these expressions, the
language of the internal functions enter into our poetry, which in
consequence is the language of the passions or the organic life, as
ordinary speech, is that of the understanding or the animal life.
Declamation holds a middle place between the two, and animates the
cold language of the brain by the expressive language of the inward
organs.
I shall even venture to assert that anger and love inoculate,
if I may so express myself, into the humours, into the saliva
particularly, a radical vice, which renders dangerous the bite of
animals at such times; for these passions do really distil into the
fluids a poison, as we indicate the fact by our common expressions.
The violent passions of the nurse have frequently given her milk a
pernicious quality, from whence disease has followed to the child;
and in the same way shall we explain from the modifications which
the blood of the mother receives under strong emotion, the manner,
in which these emotions operate on the nutrition, the conformation,
and even on the life of the fœtus. And not only do the passions
essentially influence the organic functions, in affecting their
respective viscera, but the state of these viscera, their lesions,
the variation of their forces concur in a decided way to the
production of the passions themselves. Their relations with age and
temperament, establish incontestably this fact.
Who does not know for instance, that the individual of the sanguine
temperament, whose expansion of lungs is great, whose circulatory
system is large and strong; who does not know that such a man
is possessed of a disposition to anger and violence? that when
the bilious system prevails, the passions of envy and hatred are
more particularly developed? that when the lymphatic system is
pronounced, are pronounced also the inactivity and dulness of the
individual?
In general that which characterises any particular temperament,
consists in a correspondent modification on one hand of the
passions, and on the other of the state of the organic viscera. The
animal life is almost always a stranger to the attributes of the
temperaments.
The same may be said of age; the weakness of the organization of
the child coincides with his timidity. The development of the
pulmonary and vascular system, with the courage and temerity of the
youth; that of the liver, and the gastric system with the envy,
ambition and intrigue of manhood.
In considering the passions as affected by climate and season, the
same relations are observed between them and the organic functions;
but physicians have sufficiently noticed these analogies, and it
would be useless to repeat them.
At present, if from man in a state of health, we look to man in
a state of disease, we shall see that the lesions of the liver,
of the stomach, of the spleen, the intestines and heart produce a
variety of alterations in our affections, which all of them cease
together with their causes.
The ancients, better than our modern mechanicians, then were
acquainted with the laws of the economy, in supposing that our bad
affections were evacuated by purgatives, together with the noxious
humours of the body. By disembarrassing the primæ viæ they got rid
of these affections. In fact how dark a tint does the fulness of
the gastric viscera cast upon the countenance! the errors of the
first physicians on the subject of the atrabilis, were a proof
of the precision of their observations on the connexion of these
organs with the state of the mind.
In this way every thing tends to prove, that the organic life, is
the term, in which the passions end, and the centre from whence
they originate. But we shall be asked perhaps, why vegetables,
which live organically, do not offer any vestige of them? the
reason seems to be, that besides their want of the natural
excitants of the passions, namely the external apparatus of the
senses, they are wanting also in those internal organs, which
concur most especially to their production, such as the digestive
system, that of the general circulation, and that of the great
secretions, which are remarked in animals.
Such are the reasons also why the passions are so obscure in the
Zoophytes, in worms, &c. and why in proportion as the organic
life becomes more simple in the series of animals, and loses its
important viscera, the passions are less observable.
III. _The passions modify the actions of the animal life though
seated in the organic life._
Although the passions are the especial attributes of the organic
life, they nevertheless exert an influence over the animal life,
which it is necessary to examine. The muscles of volition are
frequently brought into play, and their actions sometimes exalted,
sometimes lowered by them; the strength for instance of the man
in anger is doubled, and tripled; is exercised with an energy, of
which he is not himself the master. The source of this augmented
power is manifestly in the heart.
This organ, as I shall prove hereafter, is the natural excitant
of the brain, by means of the blood, which it sends thither. The
energy of the cerebral action is in proportion to the energy of
the stimulus applied to it, and we have seen that the effect of
anger is to impress a great vivacity upon the circulation; hence,
a larger quantity of blood than usual is thrown upon the brain in
a given time. The consequence is an effect analogous to that which
happens in the paroxysm of ardent fever, or the immoderate use of
wine.
It is then, that the brain being excited strongly, excites as
strongly the muscles which are submitted to its influence;
accordingly their motions must be involuntary, for the will is a
stranger to those spasms, which are determined by a cause which
irritates the medullary organ. Such cause may be a splinter of
bone, blood, pus, the handle of a scalpel as in our experiments; in
short of various kinds.
The analogy is exact, the blood being transmitted to the brain in
greater quantity than usual, produces upon it the effect of the
different excitants above mentioned. In these different motions
then, the brain is passive; it engenders indeed at all times the
necessary irradiations for producing such motions, but these
irradiations in the present instance are not the effect of the will.
It may be observed also, that under the influence of anger, a
constant relation exists between the contractions of the heart and
the locomotive organs; they both increase at the same time, and at
the same time resume their equilibrium. In every other case on the
contrary there is no appearance of this relation; the action of the
heart is uniformly the same, whatever the affection of the muscular
system. In convulsion and palsy, the circulation is neither impeded
nor accelerated.
In the passion of anger, in fact, we see the very mode of the
influence, which the organic life exercises over the animal life.
In the passion of fear also, where on the one hand the enfeebled
heart directs a less quantity of blood, and consequently a smaller
cause of excitement to the brain, and where on the other hand a
debility may be observed in the external muscles, we may perceive
the connexion of cause and effect. This passion offers in the first
degree the phenomenon, which in the last degree is shewn by those
lively emotions, which suspending altogether the efforts of the
heart, occasion a sudden cessation of the animal life and syncope.
But in what way shall we account for those modifications of the
motions of the animal life, which are the effect of the passions?
In what way shall we explain the cause of those infinite varieties,
which succeed each other in the moveable picture of the face?
All the muscles which are the agents of these motions receive their
nerves from the brain and lie under the influence of the will. What
is the reason then, that when acted on by the passions, they cease
to do so, and enter under the class of those motions of the organic
life, which are put forth without our direction or consciousness.
The following if I mistake not is the best explanation of the fact.
The most numerous sympathies exist between the internal viscera,
and the brain or its different parts. Every step which we make
in practice presents us with affections of the brain originating
sympathetically from those of the liver, stomach and intestines.
Now as the effect of every kind of passion is to produce a change
of power in one or the other of these viscera, such change will
sympathetically excite either the whole of the brain or some of its
parts, whose re-action upon the muscles, which receive from thence
their nerves, will produce the motions, which are then observed.
In the production of these motions the cerebral organ accordingly
must be passive, it is active only when the will presides over its
efforts.
The effects indeed of the passions are similar to those diseases
of the internal organs, which by sympathy are the causes of atony,
palsy, and spasm.
But perhaps the inward organs act upon the voluntary muscles, not
by means of the immediate excitement of the brain, but by direct
nervous communication. Of what importance to us is the manner? We
are not at present occupied on the so much agitated question of the
manner of sympathetic communication.
The essential thing is the fact itself. Now in this fact, there
are two things evident; the affection of an internal organ by the
passions, and secondly a motion produced in consequence of such
affection in muscles, on which this organ in the common series of
the phenomena of the two lives has no kind of influence. This is
surely a sympathy, for between it, and those with which convulsion,
or spasm of the face present us, when occasioned by any lesion of
the phrenic centre, or the stomach, the difference is only in the
cause, which affects the internal organ.
Any irritation of the uvula, or the pharynx convulsively agitates
the diaphragm. The too frequently repeated use of fermented liquors
occasions a general trembling of the body. But that which happens
in one mode of gastric affection, may happen in another. What
matters it, whether the stomach or liver be irritated by passion or
by some material cause? It is from the affection, and not from the
cause of the affection that results the sympathy.
Such in general is the manner in which the passions withdraw
from the empire of the will, those motions which by nature are
voluntary. Such is the manner in which they appropriate to
themselves, if I may so express myself, the phenomena of the animal
life, though they possess their seat essentially in the organic
life.
When very strong, the very lively affection of the internal organs
produces so impetuously the sympathetic motions of the muscles,
that the action of the brain is absolutely null upon them; but the
first impression past, the ordinary mode of locomotion returns.
A man is informed by letter and in presence of company, of a piece
of news, which it is his interest to conceal. All on a sudden
his brows become contracted, he grows pale, and his features are
moulded according to the nature of the passion, which has been
excited. These are sympathetic phenomena produced by the abdominal
viscera which have been affected by the passions, and which in
consequence belong to the organic life. But in a short time the man
is capable of putting a constraint upon himself, his countenance
clears up, his colour returns. Meanwhile the interior sentiment
continues to subsist however, but the voluntary have overpowered
the sympathetic motions, the action of the brain has surmounted
that of the stomach or the liver; the animal life of the man has
resumed its empire.
In almost all the passions the movements of the animal life are
mingled with those of the organic life, or succeed to them; in
almost all the passions, the muscular action is in part directed
by the brain, in part by the organic viscera. The two centres
alternately overpowered the one by the other, or remaining in a
state of equilibrium, constitute by the modifications of their
influence, those numerous varieties which are seen in our mental
affections.
And not only on the brain, but on all the other parts of the
body also do the viscera affected by the passions exercise their
sympathetic influence. Fear affects the stomach in the first
place, as is proved by the sense of stricture felt there at such
time.[16] But when thus affected, the organ re-acts upon the skin,
with which it has so strict a connexion, and the skin immediately
becomes the seat of the cold and sudden sweat, which is then so
often felt. This sweat is still however of the same nature with
that which is occasioned by tea, or warm liquids. Thus a glass of
cold water, or a current of cold air, will suppress this excretion
by means of the relation, which exists between the skin, and the
mucous surfaces of the stomach or bronchiæ. We must carefully
distinguish between sympathetic sweating, and that, of which the
cause is directly made upon the skin.
Hence though the brain be not the only term of the re-action of
the internal viscera which are affected by the passions, it is
nevertheless the principal one, and in this respect may always be
considered as a focus at all times in opposition to that which is
centered in the internal organs.
IV. _Of the epigastric centre.--It does not exist in the sense,
which Authors have pretended._
Authors have never been at variance with respect to the cerebral
focus. The voluntary motions have ever been regarded as an
effect of its irradiations. They do not equally agree upon the
subject of the epigastric focus; some of them place it in the
diaphragm, others in the pylorus, others in the plexus of the great
sympathetic nerve.[17]
But on this point, they appear to me to be all of them in the
wrong. They assimilate or rather identify the second with the first
focus--they think, that the passions, as well as the sensations
have their seat in an invariable centre. That, which has led them
to this opinion has been the sentiment of oppression, which is felt
at the cardia under all painful affection.
But it is to be remarked, that in the internal organs, the
sentiment produced by the affection of a part is always an
unfaithful index of the seat and extent of such affection. For
example, hunger must undoubtedly affect the whole of the stomach,
but the sensation of hunger is transmitted to us only by the
cardia. A large inflamed surface in the pleura for the most part
gives rise to a pain, which is felt only in a point. How often does
it happen that in the head or the abdomen a pain which is referred
but to a very limited space coincides with a largely disseminated
affection, with an affection possessing even a different seat
from that which is presumed. We should never consider the place
to which we refer the sentiment as a sure index of that which the
affection occupies, but only as a sign that it exists either there
or thereabouts.
From all this it follows, that to form a judgment of the organ,
to which such or such a passion relates, we ought to recur to the
effect produced in the functions of the organ by the influence of
the passion, and not to the feelings of the patient. In setting out
from this principle it will be easy to see, that it is sometimes
the stomach and alimentary canal, sometimes the sanguiferous
system, sometimes the viscera belonging to the secretions which
experience a change.
I shall not repeat the proofs of this assertion, but supposing it
to be demonstrated, I shall assert that there does not exist for
the passions as there does for the sensations a fixed and constant
centre; that on the contrary the liver, the lungs, the spleen, the
stomach, and the heart, are turn by turn affected, and at such time
form that epigastric centre so celebrated in modern works; and if
in general we refer to this region the sensible impression of all
our affections, the reason is that all the important viscera of
the organic life, are there concentrated. In fact, if nature had
separated these viscera, had the liver for instance been placed
in the pelvis, and the stomach in the neck, the heart and spleen
remaining as they now are seated, in such case the epigastric focus
would disappear, and the local sentiment of our passions vary
according to the part affected.
In determining the facial angle, Camper has thrown much light upon
the proportion of intelligence enjoyed by the several classes of
animals. It appears that not only the functions of the brain, but
that all those of the animal life which are centred there, have
this angle for the measure of their perfection.
It would be a very pleasing thing could we indicate in the same
way a measure, which assumed from the organs of the internal life,
might fix the rank of each species with regard to the passions. The
dog is much more susceptible than other animals of the sentiments
of gratitude, of joy, of sorrow, of hatred, and of friendship;
has he any thing more perfect in his organic life? the monkey
astonishes us by his industry, his disposition to imitate, and
by his intelligence; his animal life is certainly superior to
that of every other species. Other animals, such as the elephant,
interest us by their attachment, their affection, their passions;
they delight us also with their address, and the extent of their
intelligence. With them the cerebral centre and the organic viscera
are perfect alike.
A rapid glance over the series of animals will show us also,
that in some of them the phenomena, which arise from sensation
predominate over those which have their origin in the passions;
in others we shall see the latter superior in power to the
former, and in others again, a balance established between the
two. These circumstances, which we remark in the long chain of
animated beings, we may remark in the human species when considered
individually. In one man the passions are the great principle of
motion; the influence of his animal life is continually surpassed
by that of his organic life, and incessantly induces him to act
in a way to which the will is almost a stranger, and which often
entails upon him the bitterest regret, when his animal life resumes
its empire. In another man, the animal life is the stronger of the
two. In such case, the understanding seems to be augmented at the
expense of the passions, the latter remaining in that silence, to
which the organization of the individual has condemned them.
That man enjoys the happiest constitution in whom the two lives
are balanced, in whom the cerebral and epigastric centres exercise
the one upon the other an equal action, whose intellect is warmed,
exalted, and animated by the passions, but whose judgment makes him
at all times master of their influence.
It is this influence of the passions over the actions of the animal
life, which composes what is named the character. Character as well
as Temperament depends upon the organic life; possesses all its
attributes, and is a stranger to the will in all its emanations;
for our exterior actions form a picture of which the ground and
design do indeed belong to the animal life, but upon which the
organic life extends the shading and colouring of the passions.
The character of the individual is constituted by such shades and
colours.
The alternate predominance of the two lives has been remarked
by almost all philosophers. Plato, Marcus Aurelius, Bacon, St.
Augustine, St. Paul, Leibnitz, Van Helmont, Buffon and many others,
have recognized in man two principles, by one of which we become
the masters of all our moral actions, by the other the contrary.
We have nothing to do with the nature of these principles. Our
business is with their phenomena; we shall analyze the relations by
which they are united.
FOOTNOTES:
[15] Bichat, in this paragraph, seems to say that the perceptions,
which produce in us the passions, go directly and without the
intervention of the brain, from the senses to the organs which he
supposes to be affected by them. We cannot believe that such was
his idea. The paragraph which follows must aid us in understanding
it, and we shall endeavour to elucidate it by means of an example.
A certain event happens; a man is informed of it by means of his
senses; he examines the event in itself, and its relations with
antecedent and future events; his judgment weighs the various
consequences of it, and shows them to be very disadvantageous to
him. Here, as Bichat calls it, is a cold series of intellectual
phenomena, which would take place in the individual, whoever the
man may be who is affected by the event to which he has given his
attention. It is found that the man who is injured is himself;
then, from a knowledge of this only, his heart is sympathetically
affected; its motions become more rapid and stronger, they send
to the brain a greater quantity of blood, and this increase of
habitual excitement in the organ of thought, produces a kind of
mental attention in relation to the event that has taken place.
Thus, without the part that the heart has taken in it, this man
would have seen with the most perfect indifference an event most
disastrous to himself; for without even supposing anger, the least
sentiment of sadness being a passion, we cannot believe that he
is affected with it, if his liver, stomach or spleen are not at
the moment in a particular state. But does not every thing on the
contrary lead us to believe that anger exists before the agitation
of the heart, and that this is the effect of it and not the cause?
This agitation of the heart without doubt, by sending to the brain
a greater quantity of blood than usual, contributes in its turn to
develop and support the kind of alienation which accompanies anger;
but it is necessary that the passion should already exist, since a
favourable event, by producing as rapid motions of the heart, will
produce nothing similar.
[16] There is no proof that the sense of stricture which is felt
in the epigastric region, is connected with the stomach; and if it
were proved that it was so, it would not follow from it that this
organ was primarily affected from fear. The same passion sometimes
acts differently in different individuals; there are some who do
not feel this stricture in the epigastric region, but who are
deprived of the use of their legs; must it be said that in these
individuals the seat of fear is in the extensor muscles of the
legs? If the introduction of a warm drink into the stomach produces
an increase of cutaneous exhalation, should we conclude from
analogy, that it is by acting primarily upon this organ that fear
causes that cold sweat which sometimes accompanies it?
[17] _Note by the Author._--This nervous network, going principally
from the semi-lunar ganglion, belongs to almost the whole
abdominal vascular system, whose various ramifications it follows.
It is, according to the usual manner of considering it, one of
the divisions of the great sympathetic; but it seems to me that
the ideas of anatomists respecting this important nerve are not
conformable to nature.
Every one considers it as a medullary cord, extending from the head
to the sacrum, sending in its course various ramifications to the
neck, the thorax and the abdomen, following in its distributions
a course analogous to those nerves of the spine, and deriving its
origin from those nerves, according to some, and from those of the
brain, according to others. Whatever be the name by which it is
designated, sympathetic, intercostal, &c.; the manner of describing
it is always the same.
I believe that this manner is altogether wrong, that there really
exists no nerve analogous to the one designated by these words, and
that what is taken for a nerve is only a series of communications
between different nervous centres, placed at different distances
from each other.
These nervous centres are the ganglions, scattered throughout the
different regions, they have all an independent and insulated
action. Each is a particular centre which sends in various
directions many ramifications, which carry to their respective
organs the irradiations of the centre from which they go off. Among
these ramifications, some go from one ganglion to another; and as
these branches which unite the ganglions form by their union a kind
of continuous cord, this has been considered as a distinct nerve;
but these branches are only communications, simple anastomoses, and
not a nerve analogous to the others.
This is so true, that these communications are often interrupted.
There are subjects, for example, in whom is found a very distinct
interval between the pectoral and lumbar portions of what is called
the great sympathetic, which seems to be cut off in this place.
I have seen this pretended nerve cease and afterwards reappear,
either in the lumbar or sacral region. Who does not know that
sometimes a single branch, sometimes many go from one ganglion to
another, especially between the last cervical and the first dorsal;
that the size of these branches varies remarkably; and that after
having furnished many divisions, the sympathetic is larger than
before it gave off any?
These considerations evidently prove that the communicating
branches of the ganglions no more suppose a continuous nerve than
the branches which go from each of the cervical, lumbar or sacral
pair to the two pair which are superior and inferior to them. In
fact, notwithstanding these communications, we consider each pair
in a separate manner, and do not regard their union as a nerve.
It is necessary to describe in the same way separately each
ganglion, and the branches which go off from it.
Hence I shall divide hereafter in my descriptions, in which I
have hitherto pursued the ordinary course, the nerves into two
great systems, one arising from the brain, and the other from the
ganglions; the first has a single centre, the second has a great
number of them.
I shall first examine the divisions of the cerebral system; I
shall afterwards treat of the system of the ganglions, which may
be subdivided into those of the head, the neck, the thorax, the
abdomen and the pelvis.
In the head is found the lenticular ganglion, that of Meckel, that
of the sublingual gland, &c. &c. Though no communication connects
these different centres, either together or with the pretended
great sympathetic, yet their description belongs to that of the
nerves of which this is the connecting link, as the communications
are arrangements merely accidental to this system of nerves.
In the neck there are the three cervical ganglions, sometimes
another upon the side of the trachea, in the thorax the twelve
thoracic, in the abdomen the semi-lunar, the lumbar, &c. and in
the pelvis the sacral; these are the different centres whose
ramifications it is necessary to examine separately, as we do those
of the cerebral centre.
For example, I shall first describe the semi-lunar ganglion, as we
do the brain; then I shall examine the branches, among which, is
that by which it communicates with the thoracic ganglions, that is
to say, the great splanchnic; for it is very incorrect to consider
this nerve as giving origin to the ganglion. In the same way, in
the neck and the head, each ganglion will be first described;
then I shall treat of its branches, among which are those of
communications. The arrangement being nearly the same for the
ganglions of the thorax, the pelvis and the loins, the description
of each region will be similar.
This manner of describing the nerves, by placing an evident line
of demarcation between the two systems, exhibits these two systems
such as they really are in nature.
What anatomist, in fact, has not been struck with the differences
that exist between the nerves of these two systems? Those of the
brain are larger, less numerous, whiter, more compact in their
texture and exhibit less variety. On the contrary, the extreme
tenuity, great number, especially towards the plexuses, greyish
colour, remarkable softness of texture and varieties extremely
common are characters of the nerves coming from the ganglions, if
we except those of communication with the cerebral nerves and some
of those which unite together these small nervous centres.
Besides, this division of the general system of the nerves into
two secondary ones, accords very well with that of life. We know
in fact that the external functions, the sensations, locomotion
and the voice are all dependent on the cerebral nervous system;
that on the contrary, most of the organs which perform the internal
functions derive from the ganglions their nerves, and with them
the principle of their action. We know that animal sensibility and
contractility arise from the first, and that where the second alone
are found, there is only organic sensibility and contractility.
I have said that the termination of this kind of sensibility and
the origin of the corresponding contractility are in the organ in
which they are noticed; but perhaps both the termination and origin
are more remote, and are in the ganglion from which the organ
receives its nerves, as the termination of animal sensibility and
the origin of the contractility of the same species are always in
the brain. If it be so, as the ganglions are very numerous, we can
understand why the forces of organic life do not refer, like those
of animal life, to a common centre.
It is evident from these considerations, that there is no great
sympathetic nerve, and that what has been designated by this word
is only an assemblage of small nervous systems, with distinct
functions, but with communicating branches.
We see then what should be thought of the disputes of anatomists
respecting the origin of this pretended nerve, placed in the fifth,
sixth pair, &c. in those of the neck, back, &c.
Many physiologists have entertained concerning the ganglions
opinions similar to those which I have now offered, by considering
these bodies as small brains; but it is essential that these
opinions should enter into the description, which, as it is now
made, gives a very inaccurate idea both of these nervous centres
and of the nerves which go off from them.
The expression of _nervous branches giving origin to such or such a
ganglion_, &c. resembles that in which we should consider the brain
as arising from the nerves of which it is itself the origin.
CHAPTER VII.
GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO VITAL POWER.
The greater number of Physicians, who have written upon the vital
properties, have begun by researches on their principle, have
endeavoured to descend from the knowledge of the nature of this
principle to that of its phenomena, instead of ascending from
observation to theory. The Archæus of Van Helmont, the soul of
Stahl, the vital principle of Barthez, the vital power of others,
have each in their turn been considered as the sole centre of every
action possessing the character of vitality, have each in their
turn been made the common base of every physiological explanation.
But these bases have every one of them been sapped, and in the
midst of their wrecks have remained the facts alone which rigorous
experiment has furnished upon the subject of sensibility and
motility.
So narrow indeed are the limits of the human understanding, that
the knowledge of first causes has almost always been interdicted.
The veil, which covers them envelops with its innumerable folds
whoever attempts to rend it.
In the study of nature, principles are certain general results of
first causes, from whence proceed innumerable secondary results.
The art of finding the connexion of the first with the second is
that of every judicious mind. To seek the connexion of first causes
with their general effects is to walk blindfold in a road from
whence a thousand paths diverge.
Of what importance besides to us are these causes? Is it necessary
to know the nature of light, of oxygen and caloric to study their
phenomena? Without the knowledge of the principle of life, cannot
we analyze its properties? In the study of animals let us proceed
as modern metaphysicians have done in that of the understanding.
Let us suppose causes, and attach ourselves to their general
results.
I. _Difference between vital power and physical law._
In considering the powers of life, we shall perceive in the first
place a remarkable difference between them and the laws of physics.
The first incessantly vary in their intensity, in their energy, in
their development, are continually passing from the last degree of
prostration, to the highest pitch of exaltation, and assume under
the influence of the most trifling causes a thousand modifications;
for the animal is influenced by every thing which surrounds him;
he wakes, he sleeps, reposes or exercises himself, digests, or
is hungry, is subject to his own passions, and to the action of
foreign bodies. On the contrary the physical laws are invariable,
the same at all times, and the source of a series of phenomena at
all times similar. Attraction is a physical power; it is always in
proportion to the mass of brute matter in which it is observed;
sensibility is a vital power, but in the same mass of matter, in
the same organic part its quantity is perpetually changing.
The invariability of the laws which preside over the phenomena of
physics, enables us to apply the formula of calculation to all the
sciences, which have them for their object. Applied to the actions
of the living body, the mathematics can never give us formula.
The return of a comet, the resistance of a fluid in traversing an
inert canal, the rapidity of a projectile may be calculated; but
to calculate with Borelli the force of a muscle, with Keil the
velocity of the blood, with Jurine and Lavoisier the quantity of
air, which enters into the lungs, is to build upon a quicksand, an
edifice solid of itself, but necessarily decreed to fall for want
of a foundation.
This instability of the vital powers, this disposition, which they
continually have to change, impress upon all the physiological
phenomena a character of irregularity which particularly
distinguishes them from those of physics. The latter forever the
same, are well known when once they have been analyzed; but who can
say that he knows the former, because he has analyzed them under
the same circumstances, a multitude of times. The urine indeed,
the saliva, or the bile indifferently taken from such or such a
subject, may be analyzed, and hence results our animal chemistry;
but such a chemistry is the dead anatomy of the fluids, not a
physiological chemistry. The physiology of the fluids should be
composed of the innumerable variations which they experience
according to the different states of their respective organs.
The urine after taking food is not the fluid, which it is after
sleeping; it contains in winter, principles which are foreign to
it, during summer, when the principal excretions are made by the
skin. The simple passage from heat to cold, in suppressing sweat,
and the pulmonary exhalation, will change its composition. The same
is true of the other fluids; the state of the vital powers in the
organs, which are the sources of them, changes at every moment; and
therefore, the secreted substances, which entirely depend upon the
mode of action in the organs, must be as various.
Who will venture to assert, that he knows the nature of a fluid
of the living economy if he has not analyzed it in the infant, in
the adult, and the aged, in the male and in the female, at every
season, during the calm of the mind, and the storm of the passions,
which so manifestly influence its nature? To know such fluid
perfectly, will it not be requisite also to examine the different
alterations of which it is susceptible in consequence of disease?
The instability of the vital powers, is the quicksand on which have
sunk the calculations of all the Physicians of the last hundred
years. The habitual variations of the living fluids, dependent on
this instability, one would think should be no less an obstacle to
the analyzes of the chemical physicians of the present age.
From this reasoning it is easy to perceive, that the science of
organized bodies should be treated in a very different manner
from that of inorganic bodies. To the former a different language
almost is requisite; for the greater number of the words, which we
transfer from the physical sciences, into those of the animal or
vegetable economy, incessantly recall ideas, which are by no means
consistent with their phenomena.
Had physiology been cultivated by men before physics, I am
persuaded that many applications of the former would have been made
to the latter; rivers would have been seen to flow from the tonic
action of their banks, crystals to unite from the excitement, which
they exercise upon their reciprocal sensibilities, and planets to
move because they mutually irritate each other at vast distances.
All this would appear unreasonable to us, who think of gravitation
only in the consideration of these phenomena; and why should we not
in fact be as ridiculous when we come with this same gravitation,
with our affinities and chemical compositions, and with a language
established upon their fundamental data to treat of a science, with
which they have nothing whatsoever to do. Physiology would have
made a much greater progress, if all those who studied it, had set
aside the notions which are borrowed from the accessary sciences,
as they are termed. But these sciences are not accessary; they are
wholly strangers to physiology, and should be banished from it
wholly.[18]
Physics and chemistry are related to each other in many points,
because the same laws in a variety of instances preside over the
phenomena of both of them; but an immense interval divides them
from the science of organic bodies; because a very great difference
exists between the laws which are proper to them, and those of
life. To say that physiology is made up of the physics of animals,
is to give a very inaccurate idea of it; as well might we say that
astronomy is the physiology of the stars.
But the present digression has already been much too long. We shall
now consider the vital powers with respect to the two lives of the
animal.
II. _Difference between the vital properties and those of texture._
In examining the properties of every living organ, we may
distinguish them into two kinds. Those of one kind are dependent
immediately upon life, begin and finish with it, or rather form its
principle and its essence. Those of the other are connected with it
only indirectly, and appear rather to depend upon the organization
and texture of the parts of the body.
The faculties of perceiving and spontaneously contracting are vital
properties: extensibility, and the faculty of contraction upon the
cessation of the extending power, are properties of texture; the
latter it is true, are possessed of a greater energy when existing
in the living fibre, but they remain with the organ when life has
ceased; the decomposition of the organs, is the term of their
existence. I shall first examine the vital properties.
III. _Of the two kinds of sensibility; of the animal and organic
sensibilities._
It is easy to perceive, that the vital properties can be only
those of perception and motion, but in the two lives they possess
a very different character. In the organic life, sensibility is
the faculty of receiving an impression; in the animal life, it is
the faculty of receiving an impression and moreover of referring
such impression to a common centre.[19] The stomach is sensible to
the presence of aliments, the heart to the stimulus of the blood,
the excreting tube to the contact of the fluid, which is peculiar
to it; but the term of this sensibility is in the organ itself. In
the same way do the eyes, the membranes of the nose and the mouth,
the skin, and all the mucous surfaces, at their origin, receive
an impression from the bodies which are in contact with them, but
they afterwards transmit such impression to the brain, which is the
general centre of the sensibility of these organs.
There is an animal sensibility then, and an organic sensibility.
Upon the one depend the phenomena of digestion, circulation,
secretion, exhalation, absorption, and nutrition. It is common
to the plant, and the animal; the Zoophyte enjoys it as perfectly
as the most perfectly organized quadruped. On the other depend
sensation and perception, as well as the pain and pleasure which
modify them. The perfection of animals, if I may so speak, is
in proportion to the quantity of this sensibility, which has
been bestowed upon them. This species of sensibility is not the
attribute of vegetable life.
The difference of these two kinds of sensitive power is
particularly well marked in the manner of their termination, in
the case of violent and sudden death. In such case, the animal
sensibility is at once extinguished; there can no longer be found
any trace of it at the moment which succeeds to strong concussion
of the brain, to great hæmorrhage or asphyxia; but the organic
sensibility survives such accidents more or less. The lymphatics
continue to absorb, the muscle is still sensible to stimuli, the
nails and the hair continue to be nourished, and in consequence
are sensible of the fluids which they imbibe.[20] It is often
a considerable time before all traces of this sensibility are
effaced; the annihilation of the other is instantaneous.
Though at the first glance, the two sensibilities present us so
remarkable a difference, their nature nevertheless appears to be
essentially the same. The one perhaps is only the maximum of the
other, is the same force, but according to its intensity is shown
under different characters. Of this the following observations are
proofs.
There are different parts in the economy, where these faculties
are concatenated, and succeed each other insensibly. The origin of
all the mucous membranes is an example of such parts. We have the
sensation of the passage of aliments in the mouth, and the back
part of it; this sensation becomes weaker at the beginning of the
œsophagus, decreases still towards its middle, and disappears at
its end, as well as in the stomach, where the organic sensibility
only remains. The same phenomena may be observed in the urethra,
&c. In the neighbourhood of the skin, the animal sensibility
exists; it gradually diminishes, however, and becomes organic in
the interior of the system.
Divers excitants applied to the same organ may alternately produce
the one, and the other mode of sensibility. When irritated by
acids, by very concentrated alkalies, or by a cutting instrument,
the ligaments do not transmit to the brain the very strong
impression which is made upon them, but if they be twisted,
distended or rent, a lively sensation of pain is the result.[21]
I have established this fact by a number of experiments in my
treatise on the membranes. The following is another of the same
kind, which I have since observed. The parietes of the arteries
as we know are sensible to the blood by which they are traversed,
but at the same time are the term of this sentiment. If a fluid,
however, which is foreign to this system, be injected into it, the
animal will immediately discover by his cries, that he is sensible
of the presence of such fluid.[22]
We have seen that it is a property of habit, to weaken the
sentiment, to transform into indifferent sensations all those of
pleasure, or of pain. Foreign bodies, for example, will make upon
the mucous membranes a painful impression during the first days
of their application to it; they develop in such parts the animal
sensibility, but by little and little this sensibility decreases,
and the organic alone subsists. In this way the urethra is sensible
of the bougie as long as it continues there, for during the whole
of such time, the action of the mucous glands of the passage
is augmented, from whence arises a species of catarrh, but the
individual for the first moments only had a painful consciousness
of the presence of the instrument.
We every day observe, that inflammation in exalting the organic
sensibility of a part, transforms the organic into the animal
sensibility: the cartilages thus, and the serous membranes which
in their ordinary state have only the obscure sentiment, which
is necessary to their nutrition, in an inflammatory state are
possessed of an animal sensibility, which is frequently stronger
than that of the organs to which it is natural. And why? Because
the essence of inflammation consists in accumulating the powers of
the part, and this accumulation suffices for changing the mode of
the organic sensibility, which differs from the animal sensibility
in quantity only.
From these considerations it is evident that the distinction above
established with respect to sensibility consists in the different
modifications of which this power is susceptible, and not in its
nature, which is every where the same. This faculty is common to
all the organs; they are all of them possessed of it; it forms
their true vital character; but more or less abundantly distributed
to each, it gives to each a different mode of existence. No two
parts enjoy it in the same proportion. In these varieties there is
a degree, above which the brain is the term of it, beneath which
the organ alone is sensible of the impression.
If to render my ideas on this head more clear I were to use
a vulgar expression, I should say that distributed in such a
dose to an organ, sensibility is animal: in such another dose,
organic.[23]--Now that, which varies the dose of sensibility, is
sometimes the order of nature, (in which way the skin and the
nerves are more sensible than the tendons, and cartilages;) at
other times, disease; thus in doubling the dose of sensibility to
the cartilages inflammation renders them equal in this respect, and
even superior to the former, and as a thousand causes may at every
moment exalt or diminish this power in any part of the body it may
be changed at every moment from the animal to the organic type.
Hence the reason, why authors, who have made it the object of their
experiments, have come to results so different; and why some of
them have observed the periosteum and dura mater to be insensible,
while others have put them down on the contrary as endowed with an
extreme sensibility.
IV. _Of the relation which exists between the sensibility of each
organ, and foreign bodies._
Although the sensibility of each organ be subject to continual
variations, it is nevertheless distributed to each by nature in a
determined quantity; in a quantity to which it ever returns after
its alternations of augmentation or decrease. In this respect it
resembles the pendulum, which in each of its different oscillations
resumes the place to which it is brought down by gravitation.
It is this determined sum of sensibility, which especially composes
the life of each organ, and fixes the nature of its relations with
foreign bodies; in this way the ordinary sum of sensibility in the
urethra fits it for the passage of the urine, but if this sum be
augmented, as in strong erection of the penis, the above relation
ceases: the canal refuses passage to the urine, and suffers itself
to be traversed by the semen only, which in its turn has no
relation with the sensibility of the urethra when the penis is not
erected.[24]
From hence proceeds the reason of the puckering up and spasm of
the parotid, the cystic, and pancreatic ducts, as well as of the
excreting tubes in general, when the molecules of any other fluid
than that, which they are destined to convey are presented to them.
The sum of their sensibility corresponds exactly with the nature
of their respective fluids, but is disproportioned to that of any
other.[25]--The spasmodic contraction of the larynx when irritated
by any foreign body is produced in the same manner; for the same
reason the ducts, which open upon the mucous surfaces, though
at all times in contact with a variety of different fluids, are
never penetrated by them.[26] The mouths of the lacteals, however
patulous within the alimentary canal, will take up the chyle only,
they reject the fluids, which are mixed with it; for with these
their sensibility has no relation.
Such relations do not exist only between the different sensibility
of the organs, and the different fluids of the body; but they may
be exercised also between exterior substances, and the various
parts of the living system. The sum of sensibility in the bladder,
the kidneys and the salivary glands has a peculiar analogy with
cantharides and mercury. It might be thought that the sensibility
of each organ is modified, that it assumes a peculiar nature,
and that it is this diversity of nature, which constitutes the
difference of the relations of the organs with regard to bodies in
contact with them; but a number of considerations tend to prove
that such difference is occasioned, not by any difference in the
nature, but in that of the sum, the dose, the quantity of the
sensibility, if such words may be applied to a living property. I
shall adduce the following instances:--
The absorbent orifices of the serous surfaces, are sometimes bathed
for months together in the fluid of dropsies, and take up nothing.
But if the sensibility of these orifices be exalted by tonics, or
an effort of nature, in such case it will place itself, if I may so
say, in equilibrium with the fluid, and absorption will be made.
The resolution of tumours presents us with the same phenomena; as
long as the powers of the parts are weakened, the lymphatics refuse
admittance to the extravasated substances; but if the sum of these
powers be augmented by the use of resolvents, in a short time, from
the action of the lymphatics, the tumour will disappear: from the
same cause the blood, and other fluids are taken up with a sort of
avidity at times, and at others, not at all.[27]
The art of the physician, then, in the use of resolvents, must
consist in ascertaining the degree of sensibility which he
requires in the vessels for the purpose which he has in view; and
in exalting or depressing this power accordingly. In this way, in
different circumstances, resolvents may be taken from the class of
the debilitating or stimulating remedies.
The whole of the theory of inflammation is connected with the
above ideas. It is well known that the system of the canals,
which circulate the blood gives birth to a number of other small
vessels, which admit only the serous part of this fluid. Why do
not the red globules pass into the serous vessels, though there
exist a continuity of canal? The cause by no means consists in
the disproportion of the vessels to the globules as Boerhaave
has taught. The breadth of the white vessels might be double or
triple that of the red vessels, and still the globules of the
latter colour would not pass into them, if there were not to exist
a relation between the sum of the sensibility of the vessels,
and the nature of the globules. Neither will the chyme pass into
the Choledochus, though the diameter of this canal be very much
larger, than that of the attenuated molecules of the aliments. Now
in the healthy state, the quantity of sensibility in the white
vessels being inferior to that in the red ones, it is evident that
the relation necessary to the admission of the coloured globules
cannot exist. But if any cause should exalt their powers, their
sensibility will be on a par with that of the latter set of
vessels, and the passage of the fluids till then refused, will take
place with facility.
Hence it happens, that those surfaces, which are the most exposed
to such agents as exalt the sensibility, are also the most subject
to local inflammation, as may be remarked in the conjunctiva
and the lungs; at which time such is usually the increase of
sensibility in the part, that of organic, which it was, it becomes
animal, and transmits to the brain the impressions, which are made
upon it.
Inflammation lasts as long as there subsists an excess of
sensibility; by degrees it diminishes, the red globules cease to
pass into the serous vessels and resolution takes place.
From this it may be seen that the theory of inflammation is only a
natural consequence of the laws, which preside over the passage of
the fluids into their respective tubes; hence also it may be easily
conceived how unfounded are all hypotheses, which are borrowed from
hydraulics, a science, which never can be really applied to the
animal œconomy, because there is no analogy between a set of inert
tubes, and a series of living ducts.[29]
I should never have finished were I to enumerate the consequences
of this principle in the phenomena of the living man. The reader
will easily enlarge the field of these consequences, the whole of
them will form almost all the great data of physiology, and the
essential points of the theory of diseases.
But no doubt it will be asked, why the organs of the internal life
have received from nature, an inferior degree of sensibility only,
and why they do not transmit to the brain the impressions, which
they receive, while all the acts of the animal life imply this
transmission? the reason is simply this, that all the phenomena,
which establish our connexions with surrounding objects ought to
be, and are in fact under the influence of the will; while all
those, which serve for the purpose of assimilation only, escape,
and ought indeed to escape such influence. Now for a phenomenon to
depend upon the will, it is evidently requisite that the individual
be possessed of a consciousness of such phenomenon, to be withdrawn
from the influence of the will, there should exist no such
consciousness.
V. _Of the two kinds of contractility, the animal, and the organic
contractility._
Contraction is the ordinary medium, by which the motion of the
animal organs is effected; some parts, however, move by dilating
themselves, as the iris, the corpora cavernosa, the teat and
others; so that the two general faculties, from whence spontaneous
motion is derived, are contractility and active extensibility; the
latter of these should be carefully distinguished from passive
extensibility, of which in a short time we shall speak. The first
is a property of life, the second a property of texture; but as yet
there exist too few data upon the nature and mode of the motion
resulting from the former; it is exemplified in too small a number
of organs, for us to be enabled to pay much attention to it in
these general considerations--Accordingly we shall occupy ourselves
only upon the subject of contractility; with respect to that of
active extensibility, I refer to the writings of the physicians of
Montpellier.
Spontaneous motility, a faculty inherent in living bodies, as
well as sensibility, possesses two great modifications, which
differ very much from each other, accordingly as it is examined
in the phenomena of one or the other life. There is an animal
contractility, and there is an organic contractility.
The one being essentially subject to the influence of the will,
has its principle in the brain, receives from the brain the
irradiations, which put it in action, and ceases to exist when
the organs, in which it is observed, communicate no longer with
the brain; it participates besides at all times with the state of
the brain, has exclusively its seat in the voluntary muscles, and
presides over locomotion, the voice, the general movements of the
head, the thorax and abdomen. The other, which is not dependent
on a common centre, has its principle in the moving organ itself,
is a stranger to the influence of volition, and gives rise to the
phenomena of digestion, circulation, secretion, absorption, and
nutrition.
The two are quite distinct in all cases of violent death; such
death annihilates at once the animal contractility, and allows,
for a longer or shorter time, the organic contractility to be
exercised; they are essentially distinct also in all cases of
asphyxia; in these, the first is entirely suspended, the second
remains in activity; lastly they are distinct both in artificial
palsy and in that which is brought on by disease. In these, the
voluntary motions cease; the organic motions are unaltered.
Both the one and the other kind of contractility are connected with
their corresponding kinds of sensibility. They are a consequence of
them. The sensation of external objects puts in action the animal
contractility; before the organic contractility of the heart can be
exercised, its organic sensibility must be excited by the influx of
blood.
Nevertheless, the concatenation of these two kinds of faculties
is not always the same. The animal sensibility may be exercised,
and not be necessarily followed by the exercise of its analogous
contractility. There is a general relation between sensation and
locomotion, but this relation is not direct and actual. On the
contrary, the organic contractility can never be separated from the
sensibility of the same species; the re-action of the excreting
tubes is immediately connected with the action, which the secreted
fluids exercise upon them: the contraction of the heart must
necessarily succeed the influx of the blood into it. But authors
have by no means separated these two things, either in their
considerations or their language. Irritability denotes at the same
time the sensation excited in the organ from the contact of bodies,
and the contraction of the organ in reacting upon its excitants.
The reason of this difference in the relation of the two
sensibilities and contractilities to each other is very simple. In
the organic life, there is nothing intermediate in the exercise
of these two faculties. The same organ is the term, in which the
sensation ends, and the principle from whence the contraction
begins. In the animal life, on the contrary, there exists between
these two acts two intermediate functions, those of the brain
namely, and the nerves, and these by not being brought into action
may interrupt the relation in question.
To the same cause must we refer the following observation. In the
organic life there always exists a rigorous proportion between the
sensation, and the contraction. In the animal life the one may be
exalted or lowered, and the other not affected by such change.
VI. _Subdivision of the Organic contractility into two
Varieties._[30]
The animal contractility is always the same in whatever part of the
body it is situated. But there exist in the organic contractility
two essential modifications, which would seem to indicate a
difference in their nature, though there be only diversity in
outward appearances. This difference is sometimes visible, at other
times though really existing, it cannot be seen by inspection.
The sensible organic contractility may be observed in the heart,
in the stomach, intestines, bladder,[31] and other organs. It is
exercised upon very considerable quantities of the animal fluids.
The insensible organic contractility is that, by virtue of which
the excreting tubes re-act upon their respective fluids, the
secreting organs upon the blood, which flows into them, the parts
where nutrition is performed upon the nutritive juices, and the
lymphatics upon the substances which excite their open extremities;
upon all these occasions, wherever the fluids are disseminated in
small quantities, or are very much divided, this second species
of contractility is brought into exercise. A tolerably precise
idea may be given of both, by comparing the one with attraction, a
power which is exercised upon the great aggregate of matter, and
the other with the chemical affinities, the phenomena of which take
place in the molecules of different substances. For the purpose of
explaining this difference, Barthez has compared the one to the
second hand of a watch, which traverses the circumference in a very
apparent manner, and the other to the hour hand, which moves also,
but whose motion is not distinguishable.
The sensible organic contractility nearly answers to the
irritability of authors; the insensible organic contractility to
what is called tonicity. But these words seem to suppose in the
properties, which they indicate a difference of nature, while this
difference exists only in appearance. I therefore prefer employing
for both a common term. It designs their general character, that
of appertaining to the interior life, and their independence with
regard to the will. To this term I join an adjective expressive of
the particular attribute of each.
In fact we should possess a very inaccurate idea of these two modes
of action, were we to consider them as proceeding from different
principles. The one is but the extreme of the other; they are
both connected by insensible gradations. Between the obscure but
real contractility, which is necessary to the nutrition of the
nails, and the hair, &c. and that which we see in the motions of
the stomach, and intestines, there exist innumerable shades of
this property, which serve as transitions betwixt its perceptible
degrees; such are the motions of the dartos,[32] of the arteries,
and of certain parts of the cutaneous organs.
The circulation will give us a very good idea of this graduated
enchainment of the two kinds of organic contractility. The sensible
organic contractility presides over this function in the heart
and large vessels,[33] by degrees it become less apparent, in
proportion as the diameter of the vascular system decreases; and
lastly, it is insensible in the capillary tubes, where tonicity
only is observed.
Should we consider irritability as a property inherent exclusively
in the muscles, as being one of the characters by which they are
distinguished from other organs, and should we call this property
by a name expressive of its peculiar seat in the muscle, we should
conceive it, if I mistake not, in a very different way from that in
which it naturally exists.
It is true, that in this respect the muscles occupy the first
rank in the scale of the animal solids; they possess the maximum
of the organic contractility; but every living organ acts, as
they do, though in a manner less apparent upon the excitant when
artificially applied, or on the fluid, which in the natural way is
carried to it for the purpose of supplying the matter of secretion,
nutrition, exhalation, or absorption.
Nothing in consequence is more uncertain than the rule, which
is commonly adopted for pronouncing upon the muscularity of any
doubtful part; for the rule consists in ascertaining whether such
part does or does not contract under the action of stimuli.
It is thus, that a muscular tunic is admitted in the arteries,
although their organization entirely differs from that of the
muscles; it is thus, that the womb is pronounced to be fleshy,
however foreign to such structure; it is thus, that a muscular
texture is admitted in the dartos, in the iris, and other parts,
although no such structure be observable there.
The faculty of contracting under the action of irritating
substances like that of the sensibility, is unequally distributed
among the organs; they enjoy it in different degrees. We do not
properly conceive it, if we suppose that it belongs exclusively
to some of them. It does not, as some have imagined, possess its
peculiar seat in the muscular fibre. Life is the sole condition
necessary to all the fibres for enjoying it; their peculiar texture
influences the sum only, which they receive of it; it appears that
to such an organic texture, is attributed, if I may so express
myself, such a dose of contractility; to such another texture, such
another dose, and so on; so that to employ the expressions, which
I have used in treating on the subject of sensibility (however
improper they may be, yet capable alone of rendering my ideas)
the differences in the organic contractility of our different
parts, consist in the quantity only, and not in the nature of this
property: indeed it is with respect to quantity only that this
property varies, accordingly as it is considered in the muscles,
the ligaments, the nerves, or the bones.
If a special mode of contraction ought to be designed for the
muscles by a particular expression, such expression could be only
derived from the property which they have of contracting from
the influence of the will; but this property is foreign to their
texture, and comes to them from the brain only; for as soon as
they cease to communicate with this organ directly by means of the
nerves, they cease also to be the agents of voluntary motion.
These considerations lead us to examine the limits which are placed
between the one and the other kind of contractility. We have seen
that those which distinguish the two modes of sensibility, appear
to be derived only from the greater or less proportion of this
power; that in a certain proportion sensibility is of the animal
kind, in a certain inferior proportion, of the organic kind, and
that frequently from an augmentation, or diminution of intensity
the two sensibilities reciprocally borrow their respective
characters. We have seen a phenomenon almost analogous to this in
the two subdivisions of the organic contractility.
But this is not the case with regard to the two great divisions
of contractility considered in general. The organic can never
be transformed into the animal contractility. Whatever be its
increase of energy, it constantly remains the same in its nature.
The stomach, the intestines frequently assume a susceptibility
of contraction, which makes them rise up and produces in
them[34] the most violent motions by the most simple stimuli,
but these movements preserve at all times their peculiar type,
their primitive character; and have never been regulated by the
brain. From whence proceeds this difference in the phenomena of
sensibility and contractility? I cannot in a precise and rigorous
manner resolve this question.
VII. _Of the extensibility and contractility of texture._
I shall now proceed to examine the properties, which depend on
texture only, on the organic arrangement of the fibres of the
different parts. These are extensibility and contractility.
They both succeed each other, and are connected in the same way, as
in the vital phenomena, the organic and animal sensibilities are
related to their respective contractilities.
Extensibility of texture, or the faculty of being distended
beyond the ordinary state by external impulse (and in this it
is distinguished from the extensibility of the iris,[35] the
corpora cavernosa, &c.) This extensibility, I say, belongs to
many organs. The extensor muscles are very much lengthened in
strong tension of the limbs; the skin accommodates itself to
tumours; the aponeuroses, as we see in ascites and pregnancy, are
distended by what is accumulated beneath them. The mucous membranes
of the intestines, of the bladder; the serous membranes of the
greater number of the cavities present us with similar phenomena,
when these cavities are full. The fibrous membranes, the bones
themselves are susceptible of distension. Thus in hydrocephalus the
pericranium, and the bones of the cranium, in spina ventosa and
other analogous diseases, the extremities or the middle of the long
bones experience a similar distension. The kidneys, the brain, and
the liver, when abscesses are formed in their interior, the spleen
and the lungs, when penetrated by a great quantity of blood, the
ligaments in articular dropsies, in short all the organs, under
a thousand different circumstances, exemplify this property; a
property inherent in their texture, and not precisely depending on
their life; for as long as their texture remains untouched, their
extensibility subsists also, though they themselves have ceased
to live.--The decomposition of the part, from whatever cause it
happens, is the sole term of this extensibility, in which the
organs are passive at all times, and subject to the mechanical
influence of those bodies which act upon them.
There exists for the different organs a scale of extensibility,
at the top of which are those which have the greatest laxity in
the arrangement of their fibres, as the muscles, the skin, and
cellular substance; at the bottom of the scale are those which are
characterized by their density, as the bones, the cartilages, the
tendons, and the nails.
We must not, however, be deceived by appearances, with regard to
the extensibility of parts of the body; for the serous membranes,
which at the first glance would seem to be capable of great
distension, do not yield so much of themselves, as from the
development of their folds. Thus the displacement of the skin,
which abandons certain parts, while it spreads over tumours in the
vicinity, might easily give rise to the supposition of its being
capable of a much greater distension than that of which it is
really susceptible.
With extensibility of texture, there corresponds a certain mode of
contractility, which may be designated by the name of contractility
of texture. This can only take place after a previous distension.
In general the greater number of our organs are maintained in a
certain degree of tension from different causes; the locomotive
muscles by their antagonists, the hollow muscles by the different
substances which they enclose; the vessels by the fluids,
which circulate within them, the skin of a part by that of the
neighbouring parts, the alveolar parietes by the teeth which they
contain. If these causes be removed, contraction supervenes; thus,
if a long muscle be cut, its antagonist will be shortened; if
a hollow muscle be emptied, it will contract; if an artery be
deprived of its blood, it will become a ligament; if the skin be
cut into, the borders of the incision will retire from each other;
if a tooth be drawn, its cavity will be obliterated.
In these cases it is the cessation of the natural extension, which
occasions the contraction; in other cases it is the cessation of
an unnatural extension which does so. Thus, the lower belly is
straitened after puncture or delivery; the maxillary sinus, after
the extirpation of a fungus; the cellular texture, after the
opening of an abscess, the tunica vaginalis, after the operation
of hydrocele, the skin of the scrotum, after the extirpation of
the voluminous testicle, by which it was distended; the sac of an
aneurism, after the evacuation of the fluid.
This mode of contractility is not by any means dependent on life;
it belongs only to the texture, to the organic arrangement of the
part,[36] yet still receives from the vital powers an increase
of energy. Thus the retraction of a muscle, which is cut in the
dead subject, is much smaller than that of a muscle divided in the
living animal; in the same way, the retraction of the skin varies;
but though less evident, this contractility subsists always, and
like its corresponding extensibility has no other limit than that
of the decomposition of the part.
The greater number of authors have confounded the phenomena of this
contractility with those of the insensible organic contractility,
or tonicity. Of these I might reckon Haller, Blumenbach, Barthez
and others, who have referred to the same principle the return
upon themselves of the abdominal parietes, after distension, the
retraction of the skin, or a divided muscle, and the contraction
of the dartos from cold. The first of these phenomena is owing to
the contractility depending on texture, which does not suppose the
application of an irritating substance; the second, to tonicity,
which is never exercised excepting when influenced by such
application.
Neither have I myself, in my treatise on the membranes,
sufficiently distinguished these two modifications of contraction,
but we evidently ought to establish between them the most decided
limits.
An example will render this more sensible. Let us take for
it an organ, in which there may be observed all the kinds of
contractility, of which I have hitherto spoken; a voluntary muscle
for instance: In distinguishing the species with precision we may
acquire a clear and precise idea of each of them.
Now such muscle may enter into action first by the influence of
the nerves, which it receives from the brain; here it shews its
animal contractility. Secondly, it may be brought into action by
the stimulus of a physical or chemical agent applied to it, a
stimulus, which artificially creates a motion, analogous to that,
which is natural to the heart, and other involuntary muscles;--here
we have the sensible organic contractility or irritability.
Thirdly, its action may be produced by the influx of fluids, which
penetrate all its parts for the purpose of carrying thither the
matter of nutrition, and which at the same time are the occasion
of a partial oscillatory movement in each fibre, in each molecule,
a movement as necessary to the function of nutrition, as in the
glands it is indispensable to the process of secretion, or in the
lymphatics to that of absorption.[37] Such action we refer to the
insensible organic contractility or tonicity: Fourthly, by the
transverse section of the substance or body of the muscle, may be
determined the retraction of its two ends towards their points of
insertion. Here the contractility of its texture is displayed.
Any one of these kinds of contractility may cease to exist in
a muscle and the others may not be affected. Cut its nerves,
and there will be no longer any animal contractility; but the
two modifications of its organic contractility will continue to
subsist. Impregnate the muscle with opium, suffer its vessels to be
well penetrated with this substance and it will cease to contract
under the impression of stimuli, it will lose its irritability,
but it will continue to possess the tonic movements, which are
occasioned by the influx of blood into it. Lastly, kill the animal,
or rather let it live, but tie the vessels which go to the limb,
and the muscle will in such case lose its tonic power and possess
its contractility of texture only. The latter will only cease on
the supervention of sphacelus.
By these examples the different kinds of contractility may be
appreciated with respect to the organs where they are assembled
in a smaller number than in the muscles of volition; in the heart
for instance and in the intestines, where there exists a sensible
and insensible contractility, the organic being retrenched; and
again in the tendons, aponeuroses, and bones, where the animal
and sensible organic contractilities are wanting, the insensible
organic and the contractility of texture only remaining.
In general these two last are inherent in every kind of organ,
the two first belonging to some in particular only; hence for the
general character of living parts we must choose the insensible
organic contractility or tonicity, and for the character of
all organized parts whatsoever, whether living or dead, the
contractility of texture.[38]
We shall farther remark, that this last in the same way as its
corresponding extensibility possesses them, has its different
degrees, its scale of intensity, the skin and the cellular
substance on the one hand, the tendons, the aponeuroses, and the
bones on the other, forming the extremes of this scale.
From all that has been said, it is easy to perceive, that in the
contractility of every organ there are two things to be considered,
namely the contractility, or the faculty, and the cause, which puts
it in action. The contractility is always the same, belongs to
the organ, is inherent in it, but the cause which determines its
exercise may be various.
VIII. _Recapitulation of the properties of living bodies._
A recapitulation of these properties may be seen in the following
table:
_Properties._
_Classes._ _Genera._ _Species._ _Varieties._
{ { 1st Animal
{ 1st Sensibility-- {
{ { 2d Organic
1st Vital-- {
{ { 1st Animal
{ 2d Contractility--{ { 1st Sensible
{ { 2d Organic--{
{ 2d Insensible
{ 1st Extensibility
2d of Texture-- {
{ 2d Contractility
I have not inserted in this table that modification of motion,
which takes place in the iris, the corpora cavernosa, &c. a
motion, which precedes the influx of the blood, and which is not
in such way occasioned, neither have I mentioned the dilatation
of the heart,[39] and in a word that species of active and vital
excitability, of which some parts appear to be susceptible, and my
reason for this neglect, although I recognise the reality of the
modification, is my want of clear and precise ideas on the subject.
From the properties, which I have now explained, are derived all
the functions, all the phenomena, which are exemplified in the
living œconomy. There is not one, which may not be traced to them
after a strict analysis, in the same manner as in the phenomena of
physics we recur to the properties of attraction, elasticity, &c.
Wherever the vital properties are in action, there is a
disengagement, and a loss of caloric peculiar to the animal, which
compose for him a temperature independent of the medium in which he
lives. The word caloricity will hardly serve for the expression of
this fact, which is a general effect of the two great vital powers
in a state of action, and not produced by any especial faculty
distinct from them. We do not make use of the words, digestibility,
or respirability, because digestion and respiration are the results
of functions derived from the common laws of the system.
For the same reason the digestive power of Grimaud suggests an
inaccurate idea. The assimilation of heterogeneous substances to
our organs, is not the effect of any peculiar power. The same
may be said of the different principles admitted by a number of
authors, who have attributed to results and functions denominations
expressive of laws, and vital properties.
The proper life of each organ is composed of the different
modifications, to which are submitted in each of them the vital
sensibilities and mobilities, modifications, which invariably are
productive of others in the circulation and temperature of the
organ. Let it be noticed however, that each organ independently of
the general sensibility, mobility, temperature, and circulation of
the body, has a particular mode of sensation and heat, together
with a capillary circulation, which being withdrawn from the
influence of the heart, receives the influence only of the tonic
action of the part.[40] But we may pass over a point so frequently
and sufficiently discussed by other authors.
Let it here be understood that I offer what I have said on the
subject of the vital powers, only as a simple view of the different
modifications, which they experience in the two lives. These
detached ideas will in a short time form the basis of a more
extensive work.
Neither have I recapitulated the different divisions of the vital
powers, which have been adopted by authors; the reader will find
them in their works, and will easily perceive the differences,
which distinguish them from those, which I have adopted. I shall
only observe that were these divisions clear and precise, did they
suggest to all the same meaning, we should not have to regret in
the writings of Haller, Lecat, Wyth, Haen, and all the physicians
of Montpellier, a number of disputes of no importance to the
interest of science, and surely fatiguing to the student.
FOOTNOTES:
[18] Bichat often complains in his works of the injury that has
been done to the physiological sciences, by the attempts that are
made to facilitate the study of them by means of physics. He was
not competent to decide the question, not having sufficient data
in the sciences, the use of which he reprobated; the most that
he should have said, was that a bad application had been made of
them. Even this reproach was too general to be just. No doubt,
mankind have been led into errors by attempting to support on
slight foundations a science which was still in its infancy; but
even in the time of Bichat it could not be denied that it was to
the progress of these same sciences, that was owing the explanation
of many very important phenomena; that by it was ascertained what
takes place in respiration, and by what means a living body always
supports itself between certain limits of temperature, &c.
[19] It must be remembered that the existence of such a sensibility
is purely conjectural. As it is not transmitted to a common centre,
we can recognize it only by its effects. In order to explain these
effects, there is no need of admitting a similar faculty. This
sensibility moreover, if its existence should be admitted, would
be found continually in fault. The stomach, for example, allows
a substance to go out of its cavity which could never serve for
aliment, provided this substance exhibits a degree of fluidity
approaching that of chyme. The absorbents take up the most noxious
fluids, those even the action of which is sufficiently powerful to
destroy the organization of their parietes; the heart contracts
without the entrance of the blood into it, &c.
[20] This is altogether inaccurate; a nail in growing is not
nourished, any more than the mucus is nourished in the nasal
fossæ, or the urine in the bladder. The nails, the hair on the
various parts of the body and the hair of the head, all in a word
epidermoid productions, are the result of real secretions which
do not differ from the secretions of which we have just spoken,
only in this, that the product instead of remaining fluid like the
urine, or viscid like the mucus, hardens as it comes out of the
secretory organ, like the thread of the silk worm, or that of the
spider. A certain number of these organs is commonly arranged in
such a manner, that the matter secreted by each of them is found
in a fluid state in contact with that of the neighbouring organs,
with which it is agglomerated in hardening. Arranged in concentric
circles around a small cone, they produce a hollow cylinder;
extended in parallel lines upon a broad surface, they produce a
flattened lamina. Such is the manner in which the nails and the
hair are formed. We see from this that the epidermoid productions
grow, but are not nourished. The hair exhibits, it is true, an
internal cavity, filled with a coloured fluid, which appears to be
necessary for its preservation; but we can easily conceive how an
oily fluid may help to preserve it, by giving it suppleness and
thus preventing it from breaking. This fluid is poured into the
canal in which it is found, and it is not the hair which draws it
in, any more at least, than a capillary tube draws in the fluid
into which its extremity is plunged.
[21] The idea of endowing each texture with a peculiar kind of
sensibility in relation with its uses is one which pleases the
imagination. The ligaments are designed to oppose the separation of
the bones; they should remain insensible to every kind of stimulus
that does not tend to disunite these parts, and pain consequently,
should not be produced but from distension or twisting.
Unfortunately this supposition is not well founded, the facts on
which it rests were not accurately observed. It is very true that
in twisting these ligaments, the animal almost always cries out,
but it is because we at the same time stretch some neighbouring
parts endowed with sensibility. When this is prevented and the
experiment is made with proper precaution, we can twist, distend or
tear the ligament, without appearing to give the animal any pain.
[22] So, as long as the fluid is retained in the artery, which is
easily done by means of ligatures, no pain is manifested; but when
the irritating substance is carried by the vessels to the heart or
to any other sensible part, we can easily conceive that the animal
must experience pain, for the irritant always produces its effect,
whether it be carried directly to the part or arrive there by means
of the circulation.
[23] These expressions _dose_, _sum_, _quantity_ of sensibility
are incorrect, inasmuch as they exhibit this vital faculty under
the same point of view as the physical forces, as attraction,
for example; and as they present it to us as susceptible of
calculation, &c.; but, from a want of words for one science, it is
necessary, in order to make it understood, to borrow them from the
other sciences. There are expressions, like the words to _solder_,
to _glue_, to _unglue_, &c. that are used for the want of others in
the osseous system, and which really give very inaccurate ideas,
unless the mind corrects the sense.
[24] If the urine, during a perfect erection, does not go out
of the bladder, it is because the contraction of the muscles of
the perineum, and especially of the levator ani, prevents it. If
these muscles are relaxed, though the turgescence of the corpus
cavernosum and of the urethra remains the same, the urine flows out
without any other obstacle than what arises from the contraction of
the canal produced by the swelling of its parietes.
[25] These different excretory ducts do not exhibit in the mammalia
any contractility. There is no stimulus which can produce it in
them; I have tried them all in vain. In birds, on the contrary,
the ureters and the pancreatic and biliary canals are contractile,
and their motions, which return at intervals, are too well marked
to be mistaken. It appears that the contractility of the excretory
canals in the abdomen, is connected in these animals with the
absence of the diaphragm. We know in fact that this muscle in the
mammalia, assists by the pressure which it exerts, the course
of the secreted fluids, and renders useless the existence of
a peculiar motion in the canals which contain them. If it be
however pretended that this motion exists in them, but that it is
insensible, it must be allowed then, that it cannot perform the
office which is attributed to it, viz. that of obliterating an
opening often large enough to admit a quill. It is true, that if
the orifice of one of these canals be irritated for a long time, a
swelling of the membrane which lines it is sometimes produced, and
the opening is then really lessened. But in these cases there is
no occasion to be deceived; we see that this swelling is produced
at that point by the afflux of the fluids, as it would be in any
other part subjected to a similar excitement. Besides, it should
be observed that the obliquity of insertion of the excretory ducts
is alone sufficient to explain how the substances which pass in
front of their orifices are not introduced into them. In fact
these substances, at the moment of their passage, by the pressure
which they exert, tend to obliterate the opening of the canal,
by flattening its parietes against each other; it is thus that
the pressure of the urine, upon the inferior extremity of the
ureters, prevents this fluid from ascending towards the kidney. The
obliteration of the opening is but an accidental thing, and most
often is not even complete.
[26] It is not surprising, that a canal usually filled with the
excreted fluids should refuse to admit another which runs in an
opposite direction.
[27] All that is here said of the sensibility of the lymphatic
vessels, which makes them sometimes admit and sometimes reject
the effused fluids, is the more hypothetical, as it is not as yet
proved that these vessels are the agents of absorption. It should
be remarked, that the fluids that are supposed to be absorbed by
them, differ essentially in their chemical composition, from the
fluid that is usually found in their cavity. This fluid besides
varies but very little in its composition, though its appearance
is not uniformly the same; now, if it were the result of the
absorption of fluids differing from each other, its composition
ought also to vary as that of the chyle does, according to the
nature of the aliments.
Before the lymphatic vessels were known, the principal phenomena
of absorption were observed, and it was natural to attribute them
to the action of the veins. This opinion was maintained for a long
time after the discovery of the lymphatics. Finally, towards the
middle of the last century, Hunter being engaged in examining these
vessels, which he has done more to make known than any other man,
thought that they should be considered as the agents of absorption,
and this opinion was soon generally admitted. If we look for the
means by which he overthrew the ancient theory, we are astonished
to find that it was by five experiments only. Harvey did not with
equal facility obtain the acknowledgment of the circulation, and
perhaps there does not exist a second example of an opinion, which
was for a long time established, being abandoned so readily. It
should be remarked, that physiologists had not yet recovered from
the surprise produced by the discovery of a system of vessels so
extensive, and yet for so long a time unknown; they were impatient
to know the use of them; the veins had already the function of
returning to the heart the blood brought by the arteries; they
thought it would not impoverish them too much to deprive them of
the faculty of absorbing, in order to enrich the lymphatics with
it. Of the five experiments of Hunter, two are designed to prove
that the veins do not absorb, the object of the other three is to
show that the lymphatics do.
In the first experiment he injected tepid water into a portion of
intestine, and the blood which returned by the vein appeared to be
neither more diluted nor lighter than before. We cannot conceive
how by mere inspection, it is possible to judge if the blood
contains a certain quantity of absorbed water, a quantity which
must be proportionably very small, if we consider the whole amount
of blood that passes through the mesentric veins during the period
necessary for the absorption of the fluid. Hunter in the same
experiment tied the artery which went to the portion of intestine,
and examined the state of the vein. It did not swell, and its blood
did not become aqueous. But after this ligature, did the absorption
continue to go on in this portion of intestine, which still had no
doubt lymphatic vessels? This the author does not say. How moreover
should he think that the vein could continue its action when the
artery was tied?
In the second experiment Hunter injected milk into a portion of
intestine, and was unable to discover this fluid in the blood of
the mesentric veins; but at the period in which this experiment
was made, mankind were very far from being able to detect in the
blood a very small quantity of milk, and at the present day, with
all the aid derived from chemistry, we can hardly discover in
it a small quantity which is mixed directly with it. These two
experiments prove then nothing against the absorption of the veins;
as to those which he brings forward in favour of absorption by the
lymphatics, they are not more conclusive. I shall content myself
with relating one of them. He injected, into a portion of intestine
that was empty, a certain quantity of warm milk, and confined it
there by two ligatures. The veins that came from this portion were
emptied of their blood by several punctures made in their trunk.
The corresponding arteries were tied. He then returned the parts
into the abdomen, and drew them out again in half an hour. Having
examined them with attention, he observed that the veins were
almost empty, and that they contained no white fluid, whilst the
lacteals were almost full of it. But was not this white fluid that
filled them chyle rather than milk? Was it not there before the
injection of this liquid? In order to ascertain what takes place in
the lymphatic vessels during absorption, we must begin by examining
the state of these vessels before the experiment. But this is what
Hunter did not do, and it is this that renders his experiment of
no value. It is not very astonishing that he mistook the chyle
for the milk, since milk has for a long time been mistaken for
chyle. Flandrin, Professor of the Veterinary School at Alfort, has
several times repeated this experiment of Hunter; but he took care
before the injection of the milk to ascertain that the lymphatics
contained no white fluid; and he never found any in their cavity
after the experiment. I have myself many times performed this
experiment, with the same precaution, and I have uniformly obtained
the same results as those of Flandrin.
It would occupy too much time to examine all the reasons that have
been advanced for and against the absorption of the lymphatics; I
shall only relate some experiments I have made myself; but I ought
first to observe, that absorption undoubtedly takes place in parts
such as the eye, the brain, and the placenta in which the most
minute dissection has been unable to discover any lymphatic vessel.
_First experiment._--Four ounces of the decoction of rhubarb was
given to a dog, in half an hour after he was killed, and it was
found that more than half of the liquid had disappeared; the urine
evidently contained rhubarb, but the lymph in the thoracic duct
exhibited no trace of it.
_Second experiment._--A dog swallowed several ounces of alcohol
diluted with water; at the end of a quarter of an hour, the blood
of the animal had a very distinct odour of alcohol, but there was
nothing of the kind in the lymph.
Flandrin made a similar experiment on a horse, to whom he gave half
a pound of assafetida mixed with an equal quantity of honey. Six
hours after, the horse was killed. The odour of the assafetida was
very perceptible in the blood of the veins of the stomach, of the
small intestines and the cœcum; but it could not be perceived in
the lymph.
_Third experiment._--A dog was made to swallow six ounces of a
solution of Prussiate of Potash in water. In a quarter of an hour,
the urine very evidently contained some of the Prussiate; but the
lymph taken from the thoracic duct showed no appearance of it.
_Fourth experiment._--I gave to a dog, in whom I had tied the
thoracic duct, two ounces of a decoction of nux vomica. The effects
of absorption were as rapid as if the duct had been open. After the
death of the animal I satisfied myself, that the duct had been well
tied, and that there was no other branch, as there sometimes is, by
which the lymph could get to the subclavian vein.
I have varied this experiment by putting the poisonous fluid, into
the rectum, the sacs of the pleura and peritoneum. The results have
been uniformly the same.
_Fifth experiment._--M. Delille and myself made an incision into
the abdominal parietes of a dog, who had been fed very heartily
some hours before, so that the lacteals might be easily seen, and
we then drew out a portion of the small intestine upon which we
applied two ligatures three inches from each other. The lymphatics
that went from this portion of intestine were full of chyle and
very distinct. They were all tied and cut. The blood vessels were
also tied and cut, with the exception of an artery and a vein;
the portion of intestine also was cut off beyond the ligatures,
and thus it had no communication with the rest of the animal
except by the vein and artery which were left. These two vessels
were dissected with the greatest care, and even stripped of their
cellular coat, lest there might be some lymphatics concealed in
it; we then injected into the cavity of this portion of intestine
a decoction of nux vomica, and we retained it there by means of a
new ligature. This portion of intestine, covered with fine linen,
was restored to the abdomen; six minutes after, the effects of the
poison were manifested with their usual intensity.
_Sixth experiment._--M. Delille and myself separated the thigh of a
dog from his body, leaving only the crural artery and vein, which
kept up the communication between the two parts. These two vessels
were dissected with care, insulated to an extent of from two to
three inches, and even stripped of their cellular coat, for fear
it might conceal some small lymphatic vessel. Two grains of a very
active poison (the upas) were then inserted into the paw, and the
effects were as sudden and as intense as if the thigh had not been
separated from the body.
As it might be objected, that notwithstanding all the precautions
taken, the parietes of the artery or vein might still contain
some lymphatic, we varied our experiment so as to leave no doubt
on this point. The artery was cut entirely off, the communication
was reestablished between the two ends, by means of a leaden tube
introduced into their cavity, and fixed by proper ligatures.
The same was done for the vein. Thus there was no longer any
communication between the thigh and the rest of the body, except by
the arterial blood which came to the thigh, and by the venous blood
which returned to the trunk: the poison afterwards introduced into
the paw produced its effects in the ordinary time, that is in about
four minutes.
From these different experiments, it is right to conclude that the
minute branches of the veins possess the power of absorbing; that
they exert it on the surface of the mucous and serous membranes,
and in the interior of the organs; that the experiments that have
been quoted in favour of the absorption of the lymphatics are
inaccurate or incorrectly understood, and finally that there is no
proof that these vessels absorb any thing but chyle.
Is it now necessary to refer to the venous branches this
sensibility that has been attributed to the ultimate ramifications
of the lymphatics? But this sensibility, as we have already said,
would be constantly in error; the absorbent vessel does not select
one fluid in preference to another; all are indiscriminately
absorbed, even the most irritating, those in fact whose action is
sufficiently powerful to destroy the vascular parietes. Besides,
the phenomenon then continues, when it is no longer possible to
suppose the existence of this sensibility. After death even, the
venous branches absorb still as they do during life, if they are
placed in analogous circumstances; and to do this it is evident,
that an internal current must be established, which resembles the
course of the blood. I shall now relate an experiment, which I made
on this subject, and which I selected from many others, because it
appeared to me to be very conclusive.
I took the heart of a dog that had died the day before; I injected
into one of the coronary arteries some water of the temperature
of 30 degrees of the centigrade thermometer. This water returned
easily by the coronary vein to the right auricle, whence it flowed
into a vessel or dish. I poured half an ounce of slightly acid
water into the pericardium. At first the injected water exhibited
no sign of acidity; but in five or six minutes it presented
unequivocal marks of it.
Absorption then can take place without the assistance of this
sensibility, as well as of this insensible organic mobility, which
is supposed to be in the ultimate vascular extremities, in the
absorbing mouths, as they are called. But do these mouths really
exist? Do the last capillary branches terminate abruptly with a
large opening on the surface of the membranes or in the texture of
the organs? Can the absorbed fluids pass through their parietes as
oxygen does in the lungs to arrive at the blood which it modifies?
We are unable to make experiments on these small vessels, that
are not cognizable by our senses; let us make them on the large
ones, and if they permit fluids, in which they are immersed, to
pass through them, for a stronger reason we may suppose that it
takes place in the capillaries, whose parietes are so much more
delicate and consequently more permeable. Now we have confirmed by
experiments what we had suspected; the first attempts were made on
dead vessels.
I took a portion of the external jugular vein of a dog; I stripped
it of the surrounding cellular texture; I attached to each of its
extremities a glass tube by means of which I established a current
of warm water through its interior; I then immersed the vein into a
liquor slightly acid.
It is seen by the arrangement of the apparatus that there could not
be any communication between the internal current of warm water and
the external acid liquor.
During the first minutes the liquid that I collected did not
change its nature; but after five or six minutes the water became
perceptibly acid; absorption had taken place.
The same experiment was repeated on veins taken from human
subjects; the effect was the same; it was the same also with the
arteries, but a little slower from the greater thickness of their
coats.
It remained to be seen if in a living animal absorption thus took
place through the parietes of a large vessel. I know that the
textures that were permeable after death, are almost all so during
life, though the contrary is generally believed. If we inject
into the pleura of a living animal a certain quantity of ink, at
the end of an hour, and often sooner, we shall find the pleura,
the pericardium, the intercostal muscles, and the surface of the
heart itself, evidently of a black colour. It is true that the
signs of this exudation are not always apparent. Thus after death,
the transudation of the gall bladder is rendered evident by the
colouring of the neighbouring parts. During life, on the contrary,
as fast as the colouring particles are deposited, they are absorbed
by the serous membrane which covers the surrounding parts, and
carried off by the sanguineous current which runs through this
membrane and the subjacent organs.
From these considerations we must believe that absorption may take
place through the parietes of the vessel during life as after
death. To be satisfied of this I made the following experiment:
I took a young dog of about six weeks old. At this age the vascular
parietes are delicate, and consequently more likely to render
the experiment successful. I laid bare one of the jugular veins;
I insulated it perfectly in its whole length; I stripped off
carefully every thing which covered it, and especially the cellular
texture and some small vessels that ramified on it; I placed it
on a card, that it might not be in contact with the surrounding
parts; I then let fall, on its surface and opposite the middle of
the card, a thick aqueous solution of an alcoholic extract of nux
vomica, a substance the action of which is very powerful on dogs;
I took care that none of the poison could touch any thing but the
vein and the card, and that the course of blood was free in the
interior of the vessel. Before the fourth minute, the effects that
I expected appeared, at first feeble, but afterwards with so much
power as to render inflation of the lungs necessary to prevent the
death of the animal. I repeated this experiment on an adult animal
of a much larger size than the preceding one; the same effects
appeared but slower, on account of the greater thickness of the
parietes; they began to appear in fact after the tenth minute.
After satisfying myself with this result respecting the veins,
I thought I would ascertain if the arteries exhibited analogous
properties. These vessels are in a less favourable condition;
their texture is less spongy than that of the veins and with an
equal caliber, their parietes are much thicker. It was easy then
to foresee, that if the phenomenon of absorption showed itself, it
would appear much slower than in the veins; this was confirmed in
an experiment on two large rabbits, in whom I dissected perfectly
clean one of the carotid arteries. It was more than a quarter
of an hour before the solution of nux vomica passed through the
parietes of the artery. As soon as I saw the symptoms of poisoning
distinctly, I stopped moistening the vessel; yet one of the rabbits
died. In order then to convince myself that the poison had really
passed through the arterial parietes, and that it had not been
absorbed by small veins which might have escaped my dissection, I
carefully detached the vessel that had been used in the experiment;
I cut it open in its whole extent, and I made those who assisted
me taste a little of the blood, that was still adhering to the
internal surface; they all perceived in it, and I did myself, the
extreme bitterness of the extract of the nux vomica.
To these experiments may be objected a fact that is observed,
which is, that absorption does not take place the same under all
circumstances; its activity is redoubled or diminished, according
to the state of some other functions. Thus during a paroxysm of
fever, a medicine, which would usually act with great effect, often
produces, when given in a double or treble dose, no perceptible
effect. Now if absorption, was a purely mechanical phenomenon,
would it undergo modifications in relation with those of the vital
functions? Without doubt it would; for these modifications of the
functions may introduce new physical circumstances favourable or
injurious to the production of a mechanical phenomenon. Thus in the
present case, the state of fever, by accelerating the circulation
distends with blood the arteries and the veins. The fluid that is
to be absorbed must pass from the exterior to the interior of these
vessels. Now it may be easily conceived, that the quantity of blood
which they contain must have a great influence upon the production
of the phenomenon by the greater or less degree of tension of their
parietes. This is moreover completely confirmed by experiment.
We can, without producing a very great disturbance in the
functions, increase at pleasure the quantity of fluid which passes
through the blood-vessels, by carefully injecting into the veins
water the temperature of which is near that of the blood. An
artificial plethora is thus produced, followed by very curious
phenomena, of which I shall have occasion hereafter to speak. One
day while making this experiment, the idea occurred to me of seeing
what influence the plethora thus produced would exert upon the
phenomenon of absorption.
In consequence, after having injected into the veins of a dog of
middle size about a quart of water, I placed in the pleura a small
dose of a substance, the effects of which were well known to me.
These effects did not show themselves till many minutes after
the period in which they usually appear. I soon made the same
experiment on another animal with the same result.
In many other trials the effects showed themselves at the period in
which they ought to have appeared; but they were evidently weaker
and prolonged much beyond the ordinary time.
Finally, in another experiment in which I had introduced as much
water as the animal could bear and live, the effects did not appear
at all. I waited nearly half an hour for effects which commonly
show themselves in two or three minutes. Presuming then that the
distension of the vessels prevented the absorption, I endeavoured
to satisfy myself of it, by seeing if after the distension had
ceased, absorption would be any longer prevented. In consequence,
I bled the animal copiously from the jugular, and I saw, with the
greatest satisfaction, the effects appearing as the blood flowed
out.
It was proper to make the opposite experiment, that is to say to
diminish the quantity of blood, in order to see if absorption would
take place sooner. This took place in fact, as I thought it would;
about half a pound of blood was taken from an animal; the effects,
which did not usually appear till after the second minute, showed
themselves in thirty seconds.
Yet it might still be suspected, that it was less the distension of
the blood-vessels than the change of the nature of the blood that
opposed absorption. To remove this difficulty I made the following
experiment; a dog was bled copiously; the place of the blood which
he had lost was supplied by water at the temperature of 40 degrees
of the centigrade thermometer, and a certain quantity of a solution
of nux vomica was introduced into the pleura. The consequences of
it were as prompt and as powerful, as if the nature of the blood
had not been changed; it was then to the distension of the vessels
that must be attributed the want or diminution of absorption.
The consequences that may be deduced from the experiments I have
just related will acquire new force, if we connect with these facts
a multitude of pathological ones, which are every day seen; such as
the cure of dropsies, engorgements and inflammations by bleeding;
the evident want of action of medicines at the moment of a violent
fever, when the vascular system is powerfully distended; the
practice of certain physicians who purge and bleed their patients
before administering active medicines to them; the employment of
cinchona at the period of remission for the cure of intermittent
fevers; general or partial oedema from organic disease of the heart
or lungs, and the application of a ligature upon the extremities
after a puncture or a bite of a venomous animal, to prevent the
deleterious effects which are the consequence of it.
On the whole, I think, it may be concluded from the preceding
experiments that the capillary attraction of the small vessels is
one of the principal causes of the absorption called venous. If the
lymphatics do not appear to enjoy in the same manner the faculty of
absorption, it probably arises not from the nature of the parietes,
the physical properties of which are nearly the same as those of
the veins, but from the want of a continuous current in their
interior.
In this note I have brought together the absorption of the gases
and that of fluids. This resemblance holds only as it relates to
the permeability of the textures by these two orders of bodies. As
to the cause of the absorption of the two, it cannot be the same,
since gases are not subjected to capillary attraction.[28]
[28] _Note by the Translator of Magendie’s Additions._--In the
preceding note M. Magendie has not done justice to Mr. Hunter.
Without entering at all into the examination of the question,
whether absorption is performed by the lymphatics or the veins,
it is due to Mr. Hunter to contradict the assertion, that “he
overthrew the ancient theory by _five experiments only_.” He was
not a man who adopted his opinions loosely or on slight grounds,
and in the present case he performed between twenty and thirty
judicious and satisfactory experiments, in the presence of several
physicians and surgeons. It is true that these were performed on
five different animals only, but if the result were uniform, this
number was as good as five thousand or any other one that could be
named.
G. H.
(See Hunter’s Commentaries and Cruikshank on the Absorbents.)
[29] Those theories no doubt are very incomplete that are borrowed
from hydraulics, and probably will be so for a long time; but
it arises from this, that the science on which it is founded,
hydrodynamics, is still but little advanced. A great advance will
unquestionably be made in physiology, when we shall arrive at a
knowledge of the course of a fluid in a system of canals, which
have the same physical conditions as the system of arterial and
venous vessels. But it will be a long time before science will
have arrived at that point. Is it necessary for this to make no
use, in the explanation of the circulation, of the few facts which
are known upon the course of the fluids? Is it necessary to enter
entirely into the field of hypothesis, to suppose in the small
vessels a sensibility and a contractility which evidently do not
exist in the large ones? I cannot believe it, and I think even
that if this hypothesis should be true, and if there should be
demonstrated for the capillary vessels, those properties which are
attributed to them, and which would have an influence on the course
of the blood, we should then know but one of the conditions of this
very complicated problem, and this would not in any degree do away
the necessity of knowing all the mechanical conditions.
[30] Even in reasoning according to the hypothesis of Bichat, and
admitting the existence of this organic sensibility, it would
always be inaccurate to say, that the contraction is uniformly
in proportion to the sensation. How is it to be known in fact?
Since this sensibility is not transmitted to a common centre, it
might very well be excited without our being informed of it by any
apparent effect. Sometimes also a very evident contraction would
correspond to the slightest excitement.
[31] The contractility in the different organs in which we can
observe it does not exhibit characters so striking as those which
Bichat here assigns to it, and the motions which he ranks in
the same class have the greatest differences among them. To be
convinced how little justice there is in this division, it will
be sufficient to trace the progress of the food, along its whole
course, to the interior of the digestive canal. The first act
which is presented to our observation is entirely voluntary; this
is mastication; the act which follows it is not so completely so.
Deglutition in fact can sometimes take place against the will, if a
body of a proper consistence is at the entrance of the pharynx. We
have but an imperfect control over the muscles of the uvula and the
velum palati, if we wish to move these parts separately; we have
perhaps less power still over the contraction of the muscles of the
pharynx, though they do not appear to differ from the locomotive
muscles, either in their symmetry, or in the arrangement and colour
of their fibres, or in the nerves which they receive; nor finally
do they differ in the sudden, instantaneous contraction, wholly
different from the slow contraction, the vermicular motion of the
stomach and intestines.
After having passed the pharynx, the alimentary mass enters the
œsophagus. The motions are there still under the influence of the
nerves; but they are not at all under the influence of the will.
The muscular layer which produces them has not the appearance,
the red colour of the voluntary muscles; but it still preserves
something of the sudden motion of their contraction. Hence we see,
that the motions of the œsophagus cannot be ranked either among the
motions of organic life, since they cease by the division of the
nerves, or among those of animal life, as they are not under the
influence of the will. It is remarkable also that Bichat, who, in
this and the following paragraph, announces the characters of the
different kinds of contractility, does not speak of the œsophagus,
whilst he offers as an example the motions of the bladder, the
heart, the stomach and the intestines.
When Bichat wrote this work, hardly any thing of the motions of
the œsophagus was known, except from the writings of Haller, who
made but four experiments on the subject. I wished to observe them
myself, and I have discovered many facts which I think interesting;
I shall relate them here as I described them in a memoir read to
the Institute in 1813. Before attempting to ascertain what part
the œsophagus took in the passage of the food, it was proper to
ascertain its state when it was supposed to be at rest. In the
first experiments, I noticed an important phenomenon, and which
hitherto had escaped the observation of physiologists, viz., that
the lower third of the œsophagus has constantly an alternate motion
of contraction and relaxation, which appears to be independent of
all foreign irritation. This motion appears to be confined to the
portion of the tube which is surrounded by the plexus of nerves of
the eighth pair, that is to say, to about its lower third; there is
no trace of it in the neck nor in the superior part of the thorax.
The contraction appears like a peristaltic motion, it begins at the
junction of the superior two thirds with the inferior third, and is
continued to the insertion of this tube in the stomach. When the
contraction is once produced, it continues for an uncertain time;
usually it is less than half an hour. The œsophagus contracted
in this way in its lower third is hard like a cord powerfully
stretched. Some persons whom I have made feel of it in this state
have compared it to a rod. When the contraction has lasted the time
I have just mentioned, the relaxation takes place suddenly and
simultaneously in each of the contracted fibres; in some cases,
however, the relaxation seems to take place from the superior
fibres towards the inferior ones. The œsophagus examined during
the state of relaxation exhibits a remarkable flaccidity, which
contrasts wonderfully with the state of contraction.
This alternate motion is dependent on the nerves of the eighth
pair. When these nerves are cut in an animal, this motion entirely
ceases; the œsophagus contracts no more, but it is not in a state
of relaxation; its fibres without the control of nervous influence
shorten; it is this which produces, so far as the touch is
concerned, an intermediate state between contraction and relaxation.
When the stomach is empty or half full of food, the contraction of
the œsophagus recurs at much longer intervals; but if the stomach
be powerfully distended by any cause, the contraction of the
œsophagus is usually very powerful, and continues for a much longer
time. I have seen it, in cases of this kind, continue more than ten
minutes; under the same circumstances, that is to say, when the
stomach is excessively full, the relaxation is always much shorter.
If during the time of contraction, we wished, by mechanical
pressure made on the stomach, to make a part of the aliments which
it contained pass into the œsophagus, it would be necessary, in
order to accomplish it, to employ a very considerable force; and
often even we should not succeed. It seems that pressure increases
the intensity of the contraction, and prolongs its duration. If, on
the contrary, the stomach is pressed during relaxation, it is very
easy to make the substances it contains pass into the cavity of the
œsophagus. If it be a liquid, the slightest pressure, sometimes
even its own weight, or the tendency which the stomach itself has
to contract, will bring about this result. When the stomach is laid
bare and distended above measure, fluid does not usually enter into
the œsophagus, because, as we have said, the distension of the
stomach is a cause which prolongs the contraction of the œsophagus.
The passage of a fluid in the œsophagus is usually followed by its
entrance into the stomach. Sometimes however the fluid is thrown
out. When it goes into the stomach, the œsophagus contracts nearly
the same as in deglutition, sometimes almost immediately after it
has entered it; at other times the œsophagus allows itself to be
considerably distended before it pushes it into the stomach.
It was at the moment of deglutition that Haller observed the
motions of the œsophagus, and the description which he has given
of them is very accurate for the two superior thirds of the canal;
but the action of the inferior third is essentially different;
and this distinction seems to have escaped him. Haller says that
the relaxation of each circular fibre immediately follows the
contraction; and this is true of the portion of the canal situated
in the neck and in the superior part of the thorax; but it is
not accurate for the inferior portion, in which we see that the
contraction of all the circular fibres is continued long after
the entrance of solids or fluids into the stomach. At this moment
the mucous membrane of the cardiac extremity of the œsophagus,
pushed by the contraction of the circular fibres, forms a very
considerable projection into the cavity of the stomach. The
contraction usually coincides with the period of inspiration, when
the stomach is more strongly compressed; the relaxation takes place
most often at the time of expiration. When the aliments have once
entered the stomach, it is this contraction of the inferior part
of the œsophagus which opposes their return. The resistance that
is offered at the other orifice is not of the same species. In
living animals, whether the stomach be empty or full, the pylorus
is uniformly shut by the contraction of its fibrous ring and the
contraction of its circular fibres. There is frequently seen in the
stomach another contraction, at one or two inches distance, which
appears to be designed to prevent the aliments from arriving at the
pylorus. We perceive also irregular contractions, beginning at the
duodenum, and extending to the pyloric portion of the stomach, the
effect of which is to push back the aliments towards the splenic
part.
The aliments remain in the stomach long enough to undergo no other
modifications than those which result from their mixture with the
perspiratory and mucous fluids, which are constantly found in it
and renewed there. During this time the stomach remains uniformly
distended; but afterwards the pyloric portion contracts in its
whole extent, especially in the part nearest the splenic portion,
towards which the aliments are carried. Then there is found, in the
pyloric portion, only the chyle mixed with some unchanged aliments.
When there is accumulated in this part a quantity of it, which is
never very considerable, there is seen, after a moment of rest, a
contraction at the extremity of the duodenum; the pylorus and the
pyloric portion soon take part in this motion, and the chyle is
forced towards the splenic portion; but afterwards the motion is in
an inverse direction. The pyloric portion, which allowed itself to
be distended, contracts from left to right, and directs the chyle
towards the duodenum, which soon passes the pylorus and enters the
intestine. The same phenomenon is repeated a certain number of
times, then it ceases, and commences again after some time. This
motion, when the stomach contains much food, is limited to that
part of the organ nearest the pylorus; but as it becomes empty, the
motion extends, and appears even in the splenic portion when the
stomach is almost entirely evacuated. In general, it becomes more
evident at the end of chylification.
The motion which produces the progression of the chyle in the
small intestines is very analogous to that of the pylorus; it is
irregular, made at variable intervals, it is sometimes in one
direction and sometimes in another, and sometimes appears in many
parts at once; it is always more or less slow, it produces changes
of relations in the intestinal circumvolutions, and it is entirely
beyond the influence of the will.
We should form a very false idea of the motions of the small
intestines during digestion, if we judged of them by those which
these intestines exhibit in an animal recently killed. In this
case, it is not the annular fibres only that enter into action,
so as to exhibit, by their successive contractions, a vermicular
motion. The longitudinal fibres act also in a very conspicuous
manner, and produce a rolling of the intestinal circumvolutions,
which change their relations at every instant. These motions are
never more evident than when the whole mass of intestines is
removed from a living animal.
The motions of the large intestines have nearly the same characters
as those of the small intestines, like these last, they are not
always in the same direction, but push the substances which
are contained in their cavity, sometimes towards the ileum and
sometimes towards the anus. But by means of this motion, these
substances which have already the character of _feces_, can never
re-enter the small intestines. The cause that prevents their
return is different from that which prevents the return into the
stomach of the substances contained in the duodenum. The obstacle
in this case, we have said, is produced by the contraction of
the contractile rings, which are found at the extremity of the
two cavities; in the other, it is produced by a cause purely
mechanical, by the arrangement of the ileo-cecal valve. Hence it
follows, that if the mode of contraction of the different parts
of the intestinal canal be perverted by any cause, it might
happen that their contraction towards the pylorus would not take
place when the duodenum was affected with its anti-peristaltic
motion, and then the substances contained in it, pushed by the
contraction of the annular fibres, would re-enter the stomach. At
the coecum, on the contrary, as the obstacle is purely mechanical,
so long as the ileo-cecal valve is not broken, it will present an
insurmountable obstacle to the return of the _feces_ into the small
intestines.
The motions of the large intestines, sufficient to carry the feces
into the rectum, would not, in a state of health, be powerful
enough to expel them entirely, by overcoming the resistance which
the sphincter constantly presents; in expelling the feces, the
contraction of the intestine is assisted by the pressure which
arises from the lowering of the diaphragm, and by the contraction
of the abdominal muscles.
We have just pointed out the motions which carry the alimentary
mass along the intestines. We may see that they have but little
resemblance among them. The only character that is common to them
is that of not being under the influence of the will. Yet there is
an exception to this in some individuals who possess the faculty
of ruminating. (The will is seen exerting itself on the production
of other _sensible organic motions_. Bayle could stop at will the
pulsation of his heart.) If we examine the motions of the digestive
tube when it is free of aliments, we see their difference in a
manner not less striking. The œsophagus exhibits those alternate
motions that we have described; a very powerful contraction of its
inferior third, and then suddenly the most complete relaxation.
In the stomach we see only some undulations, that go irregularly
from one orifice to another. In the intestines, these motions
exhibit nearly the same regularity, but the groove formed by the
contraction of the annular fibres is deeper, and the undulatory
motion is not so slow. If a stimulating medicine is introduced
into the stomach, these contractions become more evident, and the
motions more rapid; but they always preserve the same character.
The contraction takes place progressively, and never in the sudden
manner of a muscle of locomotion. Of all the substances which can
be used to ascertain these motions, there is no one whose action is
more efficacious than veratrine, a new vegetable alkali extracted
from the _veratrum sabadilla_. If the external parietes of the
digestive tube be excited by any stimulus, by touching it with the
finger, by a puncture, or by the galvanic fluid, there is in the
œsophagus a sudden contraction of the longitudinal and circular
fibres, which narrows the organ and shortens it at the same time;
the relaxation takes place instantaneously and in as striking a
manner. In the stomach, no motion is perceived in the direction of
its length; we see only an annular contraction, which is developed
slowly at the excited point, and which is usually not transmitted
to the neighbouring parts. In the intestines, the excitement
produces a very decided contraction, and very often in the
neighbouring parts a kind of peristaltic motion; but this motion is
always slow and does not at all resemble the sudden contraction of
the œsophagus.
The difference between the motions of the œsophagus and those of
the other parts of the intestinal canal is very remarkable in
birds. In them the œsophagus appears to be entirely membranous; and
yet it contracts like a muscle of locomotion; whilst the stomach,
which has red muscles very similar to the locomotive muscles, has
slow, gradual vermicular motions, like all the canal which is below
it.
There exists finally between the motions of the intestinal canal a
difference relative to the manner in which they terminate. Those
of the intestines, but little sensible during life, acquire at
the moment of death a very great intensity; whilst those of the
œsophagus, before so distinct, cease immediately, and in the most
complete manner.
[32] It is not the dartos that contracts in the motions of the
scrotum, it is the skin itself that produces that vermicular
motion that is observed in this part. This motion can be produced
by stimuli of very different kinds; by the impression of cold, by
pinching the skin or by fear. I have seen these motions so great
in a man on whom I was about to operate for hydrocele, that I was
obliged to wait for a long time for fear of wounding the testicle,
which, by those motions, ascended and descended precipitately.
[33] It might be thought from this expression, that Bichat supposed
that the great arteries influenced the course of the blood by an
active contraction analogous to the muscular contraction; but
this was not his opinion. He only wished to say, that the blood
continued to move in the great arteries solely by the influence of
the heart. This contraction of the great arterial trunks has been
heretofore maintained by many anatomists, and is even at present
by some. There are at the present day three principal theories
relative to the circulation.
In the first, it is contended that all the parts of the arterial
system are irritable, and that they contract like the muscular
texture; many even add that they can dilate spontaneously, as takes
place every instant in the heart. According to this supposition,
the arteries alone would be able to continue the course of the
blood.
In the second opinion, which is that of Harvey, and which is still
adopted, more particularly by the English physiologists, it is
affirmed on the contrary, that the arteries are not contractile
in any point; that if they do contract in certain cases, it is in
virtue of that property common to all the solids, by which they
return upon themselves, when the cause that has distended them
ceases to act. The partisans of this opinion conclude that the
arteries have not and cannot have any influence upon the motion
of the blood which runs through them, and that the heart is the
principal, and as it were, the sole agent of the circulation.
Finally the third opinion, that which now prevails most generally
in France, consists in a union of the two preceding ones; the
trunks and principal arterial branches are considered as incapable
of acting upon the blood; but this property is attributed to the
small arteries, and it is thought to be very great in the last
divisions of these vessels. Thus, in this mixed opinion, the blood
is carried by the sole influence of the heart in all the arteries
of a considerable size; it is moved in part by the influence of the
heart and in part by that of the parietes in the smaller arteries,
and finally it is moved by the sole action of the parietes in the
last arterial divisions. This action of the small vessels is also
described as the principal cause of the course of the blood in the
veins.
In a question of this nature our opinion should be determined by
experiments alone. This presents many points for elucidation.
The first and the easiest to be decided is to ascertain if the
arteries are or are not irritable. The problem was in some measure
resolved in relation to the great arteries by the experiments of
Haller and his disciples, by Bichat himself, and by those which M.
Nysten has made upon man. For the purpose of being more perfectly
convinced, I have sought, by all the known means, to develop
the irritability of the arterial parietes; I have successively
subjected them to the action of pricking instruments, of caustics
and of galvanism, and I have never perceived any thing which
resembled a phenomenon of irritability; and as those who maintain
the irritability of the arteries pretend that if we do not perceive
the contractions, it is because the experiments are made on too
small animals, in whom the effects are but slightly apparent in
consequence of the small diameter of these canals, I have repeated
the experiment on large animals, on horses and asses, and I have
never observed any other motions than the communicated motions.
As the great arteries show no contraction, we ought to believe
that the small ones would not; but as among the physiologists who
reject the irritability of the arterial trunks, some like Haller,
do not speak of the branches, others accord to them contractility,
it becomes necessary to test this question by experiment; now these
small vessels, like the larger ones, remain perfectly immoveable
under the action of the scalpel, caustics and a stream of galvanic
fluid.
Irritability does not exist then in the large or the small
arteries. Respecting the last arterial divisions, as the vessels
which form them are so small that they cannot come under the
cognizance of the senses, at least in a state of health, no one can
affirm or deny that they are irritable. Yet from analogy we ought
to conclude, that they have no sensible motion. In cold-blooded
animals, in fact, it is easy to see the blood circulating in
these vessels, and even passing into the veins; now the vessels
themselves appear to be completely immoveable.
As the arteries cannot act upon the blood by contracting in the
manner of muscles, must we conclude that they have no action
upon this fluid, and that they are in relation to it nearly like
inflexible canals? I am very far from thinking so. If in fact the
arteries had no influence upon the blood, this fluid, moved by
the sole impulse of the heart, would, from its incompressibility,
be alternately in motion and at rest. This is indeed what Bichat
thought, and what he has advanced in his other works; it is what
has been since maintained in a more formal manner by Dr. Johnson
of London. It is however very easy to prove that it is not in this
way that the blood is moved in these vessels. Open a large artery
in a living animal, and the blood will escape in a continuous jet,
but by jerks; open a small artery, and the blood will flow out in
a continuous and uniform jet. The same phenomena take place in
man if the arteries are opened, either by accident or in surgical
operations. The heart being unable to produce a continuous flow,
since its action is intermittent, it must be then that the arteries
act upon the blood; this action can only be the disposition
which they have to contract, and even to obliterate their cavity
entirely. Bichat thought that his tendency to narrowing was not
sufficient in the arteries to expel the blood contained in their
cavity. He maintains that the vessel does not contract upon itself
only when the blood has ceased to distend it. If it were so, the
arteries would be equivalent to inflexible canals, and the course
of the arterial blood would not be continuous; but we can easily
demonstrate that the force with which the arteries contract is more
than sufficient to drive out the blood that they contain.
When two ligatures are applied at the same time and at some
centimetres distant upon two points of an artery which furnishes
no branches, we have a portion of artery in which the blood is
subjected only to the influence of the parietes. If we make in
this portion of the vessel a small opening, almost all the blood
that it contains is immediately thrown out, and the artery is much
contracted. This experiment has been known for a long time, and
uniformly succeeds. The following is one of my own, and places,
it seems to me, the phenomenon in a very clear light. I laid bare
the crural artery and vein of a dog to a certain extent; I passed
under these vessels, near the trunk, a string, which I afterwards
drew tightly at the posterior part of the thigh, so that all the
arterial blood should come to the limb by the crural artery, and
all the venous blood return to the trunk by the crural vein; I then
applied a ligature upon the artery, and this vessel was very soon
completely empty in the part below the ligature.
It is then satisfactorily proved that the force with which the
arteries contract upon themselves is sufficient to expel the blood
they contain. But what is the nature of this contraction? We have
proved that it cannot be attributed to irritability. Every thing
leads to the belief that it should be referred to the very great
elasticity which the arterial parietes enjoy, an elasticity that
is brought into action, when the heart forces a certain quantity
of blood into the cavity of these vessels. This property of the
arteries being known, it is easy to conceive how the principal
agent of the arterial motion, being alternate, the course of fluid
is yet continuous. The elasticity of the arterial parietes is
similar to that of the reservoir of air in certain pumps with an
alternate action, and which notwithstanding throw out the fluid in
a continuous manner.
It is not enough to know the kind of influence which the
contraction of the arteries has on the motion of the arterial
blood; it is necessary to know if this contraction does not
influence in a sensible manner the course of the blood in the
veins. This is elucidated by the following experiment. Lay bare,
as in the preceding experiment, the crural artery and vein of
a dog; tie the limb strongly, taking care not to include these
vessels; afterwards tie the crural vein, and make a small opening
in it below the ligature, of one or two lines in length; the blood
flows out in a continuous jet. If the artery be compressed, so as
to intercept the course of blood in it, the jet still continues
a short time; but it is seen sensibly to diminish, as the artery
is becoming empty. It at length ceases entirely when the artery
is completely emptied; and though the vein remains distended
with blood along its whole extent, it does not flow out at the
small wound. If the compression be taken off of the artery, the
blood enters it with force, and almost at the same instant it
begins again to flow from the opening in the vein, and the jet is
reestablished as before. If we check the course of the blood in the
artery, there is but a feeble jet from the vein; it is the same if
the passage of this fluid is alternately intercepted and permitted.
I make the same phenomenon evident in another way; I introduce into
the crural artery the extremity of a syringe filled with water at
the temperature of 30 degrees of the centigrade thermometer; I push
the piston slowly, and soon the blood goes out by the opening in
the vein, at first alone and afterwards mixed with water, and it
forms a jet the more considerable in proportion to the force with
which the piston is pushed.
To prove, as we have done, that the heart maintains an evident
influence on the course of the blood in the capillary vessels, is
not to advance that these vessels have no action on the motion of
this fluid. Many physiological phenomena, on the contrary, prove
that the capillaries can aid with more or less facility the passage
of the blood, and consequently sensibly influence its course.
[34] Under no circumstance does the stomach rise up, as Bichat
calls it. We have, in a preceding note, explained the ordinary
motions of this viscus, in a state of vacuity, during digestion and
under the influence of an internal or external stimulus. None of
these motions are sufficient to produce that sudden and energetic
expulsion which characterizes vomiting. The opinion that the
stomach rises up in vomiting originated in a time of ignorance,
and we ought not to be astonished that it should find advocates
even in our day. This has not however been uniformly adopted; Bayle
and P. Chirac opposed it by experiments; Senac, Van Swieten and
Duverney declared themselves against it; but Haller, by adopting
it, suddenly changed the views and removed the uncertainty of a
great number of physiologists, who, not taking the labour of making
experiments for themselves, loved to repose on the faith of a
celebrated name. In physiology the opinions of Haller are certainly
entitled to very great weight; this is because this wise observer,
before announcing them as a general proposition, was accustomed to
repeat many times the experiments on which he founded them; but in
this case he did not sufficiently question the use of the stomach
in vomiting.
He has made four experiments only, less for the purpose of
satisfying himself that the phenomenon existed, than to see it such
as he supposed it. It is very difficult, even for the best mind,
to divest itself in observing, of the ideas previously received
without examination. It may then be believed, that Haller in this
way saw but superficially. These considerations determined me some
years since, to satisfy myself of what takes place in vomiting,
and of the part which the stomach performs in it. I shall relate
briefly the experiments which I tried on the subject. The first
was made on a dog of middling size, whom I had made to swallow six
grains of emetic. When this medicine had excited nausea, I cut
through the linea alba opposite the stomach, and introduced my
finger into the abdomen. At each nausea, I felt it very powerfully
compressed above by the liver, which the diaphragm pushed down, and
below by the intestines, which were compressed by the abdominal
muscles. The stomach also appeared to me to be compressed; but
instead of feeling it contract, it appeared to me, on the contrary,
to increase in size. The nauseas became more frequent, and the more
marked efforts, which precede vomiting, appeared. Vomiting finally
took place, and then I felt my finger pressed with a force truly
extraordinary. The stomach rid itself of a part of the aliments it
contained; but I distinguished no sensible contraction in it. The
nausea having ceased for a short time, I enlarged the opening in
the linea alba, for the purpose of observing the stomach. As soon
as the incision was enlarged, the stomach presented itself at it,
and made an effort to come out of the abdomen; but I prevented it
with my hand. The nauseas returned in a few minutes, and I was
not a little surprized to see the stomach filled with air, as
they came on. In a very little time the organ had become three
times its former size; vomiting soon followed this dilatation,
and it was evident to all who were present, that the stomach had
been compressed without having experienced the least contraction
in its fibres. This organ rid itself of air and of a portion of
aliments; but, immediately after the exit of these substances, it
was flaccid, and it was not till after some minutes, that gradually
contracting, it became nearly of the same dimensions as it was
before the vomiting. A third vomiting took place, and we saw again
the same series of phenomena.
For the purpose of ascertaining whence the air came, which, during
the nauseas, distended the stomach, I applied a ligature on the
stomach near the pylorus, so as to close the communication which
exists between this organ and the small intestines, and I made the
dog swallow six grains more of emetic in powder. At the end of half
an hour the vomiting returned, accompanied by the same phenomena.
The distension of the stomach by air was at least as marked as
in the preceding experiment; besides there was no appearance
of contraction of the stomach, and we could not even clearly
distinguish its peristaltic motion. The animal having been killed
some moments after, in an experiment which had no relation to
vomiting, we examined the abdomen. We saw that the stomach was of
considerable size; its texture was flaccid and not all contracted;
the ligature, at the pylorus, was not displaced, and the air had
not been able to pass this way.
Having repeated this experiment and uniformly obtained the same
results, I thought it right to conclude with Chirac and Duverney,
that the mechanical pressure, exerted on the stomach by the
diaphragm and the abdominal muscles, is much concerned in the
production of vomiting; now, if it were so, by removing this
pressure from the stomach, vomiting would be prevented; experiment
confirmed this conjecture.
I injected into the vein of a dog four grains of an emetic
dissolved in two ounces of common water, (in this way vomiting is
produced quicker and more certainly;) I afterwards made an opening
in the abdomen, and when the first efforts of vomiting began, I
quickly drew out the whole of the stomach, which did not prevent
the efforts of vomiting from continuing. The animal made precisely
the same efforts as if he had vomited; but nothing came from the
stomach; this organ remained completely immoveable. I wished then
to see what would be the effect of pressure made on the stomach;
for this purpose, I placed my right hand on the anterior face of
this organ, and my left hand on the posterior face. The pressure
was hardly commenced when the efforts of vomiting, that is to
say, the contraction of the diaphragm and the abdominal muscles
powerfully recommenced. I suspended the pressure; the abdominal
muscles and diaphragm soon suspended their contractions. I renewed
the pressure; the contractions of the muscles began again; then I
suspended it; they ceased; and seven or eight times in succession.
The last time, I made a strong and continued pressure; this
produced a real vomiting. A part of the substances contained in
the stomach was thrown off. I repeated this experiment on another
dog; I observed the same facts; only I remarked moreover that the
contractions of the diaphragm and the abdominal muscles can be
produced by merely drawing by the œsophagus.
In the experiment just related, the emetic substance was introduced
into the veins, and we have already remarked, that the effects
were quicker and more certain than if the same substance had been
introduced into the stomach. This alone should make us suspect that
vomiting is not owing, as is generally believed, to the impression
of the emetic on the mucous membrane of the stomach; for, in this
case, its action ought to have been more prompt when it was placed
directly in contact with this membrane, than when it arrived at it
with the blood after having passed through the lungs and the four
cavities of the heart. For the purpose of elucidating this question
and of seeing if the contractions of the muscles were the result
of the impression produced on the stomach, or if they were excited
more directly by the emetic substance mixed with the blood, I made
the following experiment:
I opened the abdomen of a dog, and having brought the stomach out
at the opening, I tied with care the vessels that went to this
viscus, and I removed the whole of it (I ascertained in some of
the preceding experiments that a dog can live eight and forty
hours after his stomach has been removed.) I made a suture in
the abdominal parietes; then, having laid bare the crural vein,
I injected into its cavity a solution of two grains of emetic in
an ounce and a half of water. I had hardly finished the injection
when the dog began to have nausea, and he soon made all the efforts
that an animal does when he vomits. These efforts appeared to me
to be even more violent and longer continued than in ordinary
vomiting. The dog remained quiet about a quarter of an hour; I
then renewed the injection, and I forced two grains more of emetic
into the crural vein; this was followed with the same efforts of
vomiting. I repeated the experiment many times and always with
the same success; but this experiment suggested to me another,
which I performed in the following way: I took a dog of good size,
from whom I removed the stomach, as I had done in the preceding
experiment; I introduced into the abdomen a hog’s bladder, to the
neck of which I had fixed, by threads, a canula of gum elastic; I
put the end of this canula into the extremity of the œsophagus, and
I fixed it there also by threads, so that the bladder resembled
somewhat the stomach, and was, like it, in communication with the
œsophagus. I introduced into the bladder about a pint of common
water; this distended it, but did not fill it completely. A suture
was made in the wound of the abdomen, and four grains of emetic
were injected into the jugular vein. Nausea soon appeared, and
was followed with real efforts of vomiting; finally, after some
minutes, the animal vomited up abundantly the water from the
bladder.
It followed evidently from the preceding experiments, that the
abdominal muscles and the diaphragm concurred to produce vomiting;
but it remained to be ascertained, what was the part of the
diaphragm in the production of this phenomenon, and what was that
of the abdominal muscles.
If the diaphragm received only diaphragmatic nerves, it would be
easy to resist the contraction of this muscle by dividing these
nerves; but it also receives filaments from dorsal pairs, and
these filaments are sufficient to support its contractions. Yet
experiment shows us, that the diaphragmatic nerves being cut, the
contraction of the diaphragm is very evidently diminished in power,
and it may be said, without much hazard of mistake, that this
muscle loses, by this division, three quarters of its contractile
force. It was then useful to see what influence the division of
these nerves would have on the production of this phenomenon. I
made this division in the neck of a dog of three years old, and I
afterwards injected into the jugular vein three grains of emetic;
there was only a very feeble vomiting; another injection of emetic,
a quarter of an hour after, excited no vomiting. I opened the
abdomen and endeavoured to produce vomiting by compressing the
stomach. The compression, though very powerful and long continued,
excited no effort of vomiting; it did not even appear to produce
nausea. I thought that this circumstance might be owing to the
idiosyncrasy of the animal; but having many times since repeated
this experiment, I have never obtained any other result.
In order to understand what part the abdominal muscles by their
contractions take in vomiting, we ought to observe what takes
place when these muscles are unable to act. There is but one way
of coming at this, which is, to separate these muscles from their
attachments at the sides of the linea alba; this we have done on
many animals; we have detached successively the external oblique,
the internal oblique and the transversalis, leaving on the anterior
face of the abdomen only the peritoneum. When these muscles are
thus removed, we can see very distinctly through the peritoneum,
all that takes place in this cavity; we distinguish, for example,
perfectly the peristaltic motion of the stomach and the intestines;
and if the stomach contracts it will be easy to see it. The
abdominal muscles being thus detached, I injected three grains
of emetic into the jugular vein, and also immediately nausea and
vomiting took place by the contraction of the diaphragm alone. It
was curious to see, in the convulsive contraction of this muscle,
the whole intestinal mass pushed downwards, and pressing strongly
against the peritoneum, which was ruptured in some places. In this
case, the linea alba, formed by a very strong fibrous texture,
is the only part which resists the pressure of the viscera; its
existence then is indispensable to the action of vomiting; perhaps
it performs an analogous office in the ordinary state. This
experiment proves that vomiting can be produced by the efforts
of the diaphragm alone; this is also confirmed by the following
experiment:
I detached, as above, the abdominal muscles and laid bare the
peritoneum; I afterwards divided the diaphragmatic nerves, and
injected an emetic into the veins. The animal had some nausea, but
nothing more. Though I repeated many times the injection of the
emetic, I never was able to produce any sensible effort of vomiting.
From the different experiments that we have just related, and from
the facts that we made known in a preceding note relative to the
motions of the œsophagus, we may conclude, without any hazard,
1st. That vomiting can take place without any contraction of the
stomach.
2d. That the pressure exerted immediately on the stomach by the
diaphragm and abdominal muscles, appears to be sufficient to
produce vomiting, when the occlusion of the inferior part of the
œsophagus offers no obstacle to it.
3d. That the convulsive contraction of the diaphragm and abdominal
muscles, in vomiting from tartarized antimony and emetic substances
properly so called, is the result of a direct action of these
substances on the nervous system and independent of the impression
felt by the stomach.
[35] The motions of the iris cannot be attributed to an active
expansion of an erectile texture; they are owing to the
contractions of two muscular layers, one of which is radiated and
enlarges the opening of the pupil, the other is orbicular and
contracts it.
The motions of the iris, like all those which have muscular
contraction for their cause, can be excited for a considerable time
after death by the galvanic fluid. During life, the motions of the
pupil are produced in man, by the more or less vivid impression of
light on the retina. But they are beyond the influence of the will;
in birds on the contrary, they appear to be entirely subjected
to it. In these animals, we can even after death, and on an eye
entirely detached from the body, produce the motions of the iris by
pricking the optic nerve.
[36] When a patient dies after having for a long time been
deprived of solid and liquid nourishment, it is not rare to find
in him the stomach and intestines considerably lessened in their
two dimensions, the internal cavity almost entirely effaced, the
length being hardly a third of what it was before the disease.
We truly say then with Bichat that is a contraction from a want
of extension. But that this mode of contractility is as he says
perfectly independent of life and owing only to the arrangement
of parts, is what cannot be admitted. If it were so in fact, by
emptying the stomach after death, we might produce a contraction
similar to that which is produced during life. Now experiment shows
us, that this does not take place. The stomach when emptied remains
flaccid, and does not contract in any perceptible degree.
[37] We know that the organs are nourished, that the glands
secrete, we know that certain vessels absorb (whether they be
the lymphatics or not,) but we do not know, that all this is
produced by a _partial oscillatory movement in each fibre, in each
molecule_. No one can be certain that this movement takes place,
because no one has seen it.
[38] Why invent a new word, when we have that of elasticity,
which expresses for all bodies whether organic or inorganic, that
tendency to resume their usual form and size, when the cause that
made them change them is no longer in exercise?
[39] Bichat here unites three sorts of motion which have no
relation between them; the systole of the cavities of the heart
should be considered as a really active dilatation. The increase of
size of the corpora cavernosa, which is an effect purely passive of
the accumulation of blood in those parts, and which can be produced
after death by artificially accelerating the circulation in them;
and finally, the motion of the iris, a motion evidently produced
by a muscular contraction, excitable by galvanism or pricking the
nerve.
[40] Without denying the influence which the capillary systems of
the different organs have on the circulation, we have shown that
even in the veins the action of the heart is felt and modifies the
course of the blood.
CHAPTER VIII.
OF THE ORIGIN AND DEVELOPMENT OF THE ANIMAL LIFE.
If there be any circumstance, which establishes a real line of
demarcation between the two lives, this circumstance undoubtedly
is the mode and epoch of their origin. The organic life is active
from the very first moment of our existence; the animal life begins
after birth only; for without external excitants the latter is as
necessarily condemned to inaction, as without the fluids of the
œconomy, which are its internal excitants, the former would become
extinct. But the subject, on which we are now engaged deserves a
more particular discussion, and in the first place let us examine,
in what manner the animal life, which for some time is absolutely
null, is born as it were and developed.
I. _In the fœtus the first order of the functions of the animal
life is not as yet in action._
The instant, at which the fœtus begins to exist, is nearly that of
its conception; but this existence, the sphere of which is every
day enlarged, is not the same as that, which the child is destined
to enjoy after birth.
The state, in which the fœtus exists while in the womb, has been
compared to that of a profound sleep. Such comparison is inexact.
In a state of sleep the animal life is only in part suspended. In
the fœtus it has not commenced. We have seen in fact, that this
life is made up of the simultaneous or distinct exercise of the
senses, of the nerves, of the brain, of the organs of locomotion,
and the voice. Now in these different functions every thing in such
state is inactive.
Every sensation supposes the action of external bodies upon our
own, together with the perception of such action; a perception
which takes place by virtue of the sensibility of the system, which
is either general or particular, for the tact is the faculty of
perceiving general impressions, and has for its object to warn us
of the presence of bodies, together with their common attributes,
such as heat, cold, dryness, or humidity, hardness or softness. To
perceive the particular modifications of bodies is the business of
the senses.
Has the fœtus in utero any general sensations? To decide this
question, let us enquire whether any impressions are capable there
of exercising its tact. The fœtus lives in a temperature at all
times the same, swims in a fluid, and is thrown from time to time
against the parietes of the womb: such are the three sources of its
general sensations.
We shall now remark, that the two former are next to nothing,
and that the fœtus cannot have a consciousness of the medium, in
which it is nourished, nor of the heat, by which it is penetrated,
for every sensation supposes a comparison between an actual and
a past state of being. We are sensible of cold, only because we
have experienced an antecedent heat; were the temperature of
the atmosphere invariable, we should have no idea whatever of
temperature. The Laplander enjoys himself in a climate, which
would be pain, and death to the Negro, if suddenly transported
thither. It is not at the time of the solstices, but at that of
the equinoxes, that our sensations of heat, and cold are the most
lively. The reason of which must be, that at the latter seasons,
their varieties are more numerous, and occasion more frequent
comparisons between that, which we feel and that which we have felt.
What we have now said of temperature, we may repeat with respect
to the waters of the amnios: the fœtus cannot be sensible of their
influence, because the contact of any other medium is unknown to
it. Before bathing, we are not sensible of the air, after bathing,
the impression made by it upon us is unpleasant. It then affects
us because there has been an interruption of its action upon the
cutaneous organ.
Is the shock of the parietes of the matrix a more real cause of
excitement, than the waters of the amnios, or temperature? At first
we might be inclined to answer this question in the affirmative,
because the fœtus being only at intervals subject to such stimulus,
there should appear to result from thence a sensation. But let us
remark that the density[41] of the uterus in a state of pregnancy
being little greater than that of its waters, the impression must
be trifling. In fact the more the consistence of bodies resembles
that of the medium in which we live, the less powerful will be
their action upon us. Water for instance, when reduced into vapour
in our common fogs, and mists, affects the tact but slightly;
in proportion as it is condensed it is the cause of a livelier
affection.
The air then, to the animal which breathes, is truly the general
comparative term, to which he refers all the sensations of tact. If
the hand be plunged into carbonic acid gas, such substance will not
affect the tact because its density is little different from that
of the air.
The variety then of these sensations is in proportion to the
difference existing between the density of the air, and that of
the bodies, which are the occasion of such sensations. In the same
way, the measure of the sensation of the fœtus must be the excess
of density in the matrix above that of its waters. Now such excess
being very inconsiderable, the sensation of it must be very obtuse.
This assertion with respect to the fœtus will become more general
if we add to it the following: namely, that the mucous membranes,
which are the seat of an inward tact have not as yet begun to
exercise their functions. These membranes, after birth, being
continually in contact with extraneous substances, possess in these
bodies so many causes of irritation, which being continually
repeated, become excitants to the organs: but in the fœtus there is
no succession in these causes. The same urine, the same meconium,
the same mucus at all times exercise their action upon the bladder,
the intestines, and pituitary membrane.
From all this we may conclude, that the general sensations of the
fœtus are very inconsiderable, though it should appear that the
child in this state is surrounded by many of the causes, which
are hereafter to beget sensations. Neither are the particular
sensations of the fœtus more active; indeed they cannot be so for
their causes are absent.
The eye which is closed by the pupillary membrane, and the
nostrils, which are scarcely indicated, would not be capable of
receiving impressions, even in the supposition that light and
odour could act upon them. Applied against the palate, the tongue
is in contact with nothing capable of producing savour. Were it
in contact with the waters of the amnios, the effect would be the
same, because as we have said, there is no sensation, where there
is no variety of impression. The saliva of one person to another
person possesses savour, to the individual himself it is insipid.
The ear in like manner is awakened by no sound. All is calm, every
thing reposes with the little individual.
Here then we have proved, that four of the gates of sensation are
shut in the fœtus; and let us now observe that the nullity of
action in the senses which we have mentioned, must occasion very
nearly the same nullity with respect to that of the touch.[42]
In fact, this sense is especially destined to confirm the notions
which are acquired by the others, and to rectify them, for the
latter are frequently illusory--the touch is always the agent
of truth.[43] In attributing to the touch such use, nature has
submitted it directly to the will; light, odours, and sounds affect
their respective organs independently of the will.
The exercise of the other senses precedes that of the touch, they
are the occasion of it. If a man were born without sight, hearing,
smell, or taste, can we conceive in what way, he would be possessed
of the sense of touch?
The fœtus resembles such a man; it possesses wherewithal to
exercise the touch in its hands, which are already developed, and
in the parietes of the matrix. Nevertheless the fœtus is never in
action, because in seeing, in hearing, in smelling, and in tasting
nothing, it is not disposed to exercise the touch in any way. Its
members are little better than what to the tree are its branches,
which do not transmit the impression of the bodies, with which they
are entangled.
I shall here notice a great difference between the tact and
the touch; they were formerly confounded by physiologists; the
impressions of the latter are always directed by the will, those of
the former do not depend on it. We shall conclude that the portion
of the animal life which constitutes sensation, does not exist in
the fœtus.
This nullity of action in the senses supposes the same deficiency
of action in the nerves, which belong to them, and in that of the
brain from whence they issue; for the business of the former is
to transmit, of the latter to receive. Now without objects for
transmission and reception, the two functions cannot have place.
From perception are immediately derived the memory and imagination;
from these the powers of the judgment and the will. All this series
of faculties then has not had a beginning in the fœtus, because
the fœtus has not perceived, or had sensation. The brain exists
in a state of expectation, it possesses all that is requisite for
action. It does not want excitability, but stimulus. The first
division of the animal life in consequence, or that, which relates
to the action of exterior bodies, on the animal, has scarcely an
outline in the fœtus. Let us examine whether the same be true of
the second division of the animal life, or that which relates to
the reaction of the living body.
II. _Locomotion exists, but belongs in the fœtus to the organic
life._
When we see the strict connexion which exists in animals, between
sensation and their voluntary efforts, we might be induced to
believe, that voluntary motion increases or diminishes with the
increase or diminution of sentiment; for as sentiment furnishes out
the materials of the will, when it does not exist, volition cannot
exist: from induction to induction, it might thus be proved that in
the fœtus the muscles must be totally inactive.
Nevertheless the fœtus moves, and sometimes even very strong
shocks are the result of its motions. The reason why it does not
produce sound, is because the medium for the production of sound is
wanting. But how can we ally the inertia of the first part of the
animal life with the activity of the second. It is thus.
We have seen in speaking of the passions, that the muscles of
locomotion are brought into action in two manners. 1st, by the
will; 2dly, by sympathy. This last mode of action occurs, when from
the affection of an inward organ the brain is affected also, and
occasions a motion which, in such case, is involuntary. A passion,
for instance, affects the liver, the liver the brain, the brain the
voluntary muscles. Here it is the liver, not the brain, which is
the principle of motion: so that the muscles, though always thrown
into action, immediately from the irradiations of the brain, belong
nevertheless, as to their functions, sometimes to the one life,
sometimes to the other.
Hence it is easy to conceive in what way the fœtus moves: with the
fœtus, locomotion is not a portion of the animal life; its exercise
does not suppose a pre-existent will; it is purely a sympathetic
effect.
In utero the phenomena of the organic life succeed each other with
an extreme rapidity; a thousand different motions are incessantly
connected in the organs of circulation and nutrition. In these,
every thing is energetically in action. But this activity of the
organic life supposes a frequent influence exerted upon the brain
by the inward organs, and consequently as many reactions on the
part of the brain by sympathy upon the muscles. Besides, the brain
is at such time more susceptible of such sort of influence, being
much more developed than the other organs, and entirely passive on
the side of the sensations.
We may now conceive what the motions or the fœtus are. They belong
to the same class as many of those of the adult, which have not
been as yet sufficiently distinguished. They are the same as those
which are produced in the voluntary muscles by the passions;
they resemble those of the man who sleeps, and who moves without
dreaming, for nothing is more common than violent agitation in
sleep succeeding difficult digestion. The stomach is in strong
action; it acts upon the brain; the brain upon the muscles.
I might find a number of other involuntary organic motions taking
place in the voluntary muscles of the adult, and consequently
adducible to my present purpose; but what I have said on this
subject will suffice. Let us remark only, that the organic motions,
as well as the sympathetic affection of the brain, which is the
seat of them, must gradually dispose this organ, and the muscles of
the fœtus, the one to the perception of sensations, and the other
to the motions of the animal life, which are to commence after
birth. But on this head I shall refer to the memoirs of Monsieur
Cabanis.
From what has been said, then, I believe we may confidently assert,
that in the fœtus the animal life does not exist, and that all
the actions which take place at this age, depend upon the organic
life. The fœtus, indeed, has nothing of the especial character of
the animal. Its very existence is that of the vegetable; and its
destruction can only be said to be that of a living body, not of
an animated being. Thus, in the cruel alternative of sacrificing
the life of the mother, or that of the child, the choice cannot be
doubtful.
The crime of destroying a fellow-creature is much more relative
to his animal, than to his organic life.--We regret the being who
feels, who reflects, who wills, who acts accordingly, and not the
being which breathes, which is nourished, which is the seat of the
circulation and the secretions. It is the former, whose violent
death is accompanied with those images of horror, under which we
look on homicide. In proportion then as in the series of animals,
their intellectual functions diminish, is diminished also the
painful sentiment which we feel at sight of their destruction.
If the blow, which terminates by an assassination the life of a
man, were to destroy his organic life only, and suffer the other
to subsist without alteration, such blow would be regarded with
indifference, would excite neither pity for the victim, nor horror
against the aggressor.
III. _Development of the animal life, education of its organs._
A new mode of existence commences for the infant after birth; a
variety of functions are added to its organic life; their aggregate
become more complicated; their results are multiplied. As for
the animal life, it only begins; and at this period a number of
relations are established between the little individual and what
surrounds him. It is then that every thing assumes with him a
different mode of being, but at this remarkable epoch of the two
lives, where the one is augmented by almost the half, and where
the other commences only, they take upon them both a distinct
character, and the aggrandisement of the first by no means follows
the same laws as the development of the second.
We shall soon remark, that the organs of the internal life attain
at once their perfection, and that from the instant at which they
begin to act, they act with as much precision as they ever will
do. On the contrary, the organs of the external life require a
species of education; they arrive only by degrees at the perfection
which we afterwards see in them. This important difference should
be thoroughly examined. Let us begin by appreciating of what the
animal life at first consists.
In examining the different functions of this life, which start at
once into existence, we shall observe in their development a slow
and graduated progress.--We shall see, that it is insensibly and
by means of a real education that the organs attain a precision of
action.
The sensations are at first confused; they transmit only general
images; the eye has only the sensation of light; the ear that of
sound only; the nose only that of smell. As yet there is nothing
distinct in these general affections of the senses; but from habit
the strength of the first impression is lessened and the particular
sensations take place. The great differences of colours, sounds,
smells, and savours, become perceptible; by little and little their
secondary differences also are perceived, and after a certain lapse
of time the child has learnt to see, to hear, to smell, to taste,
and to touch.
After successfully undergoing the operation for the cataract, the
patient, who has previously been totally blind, is sensible of
light only, and learns by gradation to distinguish the objects
which reflect it. Another person, before whom, as I have said, for
the first time is exhibited the magnificent spectacle of an opera,
at the first glance, perceives only a whole, which delights him,
and only by degrees is able to isolate the enjoyments of which the
dance, the music, and the decorations are productive.
The education of the brain is similar to that of the senses.
Whatever depends upon its action, acquires the perfection, to which
it is destined, by degrees only. The powers of perception, memory
and imagination, which are all of them preceded and occasioned by
the sensations, increase and extend in proportion as by repeated
excitement they are brought into exercise.--The judgment, of which
they form the triple base, associates but irregularly at first its
motions, which themselves are but irregular. In a short time a
greater degree of perspicuity is observed in its operations, and
lastly they become precise and rigorous.
The voice and the agents of locomotion exemplify the same
phenomenon: the cries of young animals at first are only an
unformed sound, which possesses no sort of character: by age they
are gradually modified, and after long repeated exercise affect the
peculiar consonances of the species, by which, and particularly
during the season of their loves, the individual of the same
species is never deceived.[44] I do not instance the speech of man,
for this is evidently the fruit of education.
In examining the newly born animal, its muscles will be seen
continually in action. As every thing is new to it, every thing
is an excitant to it, and makes it move; it endeavours to touch
every thing, but neither progression, nor the power of standing
can have place when the contractions of the voluntary muscles
are so numerous. It is necessary for such, that habit shall have
taught it to combine particular contractions with other particular
contractions; until then it stumbles and falls at every moment.
Undoubtedly the inclination of the pelvis in the fœtus, the
disposition of the femora, and the want of curvature in the spine,
adapt it but little for standing immediately after birth; but with
these causes is certainly also combined the want of exercise.[45]
Who does not know, that if a limb be suffered to remain immoveable
for a length of time, it loses the habit of moving, and that when
afterwards its service is required, it requires a new kind of
education before it can exercise its movements with any regularity
or precision. The man, who for a long time should condemn himself
to silence, would experience in like manner the same embarrassment
in his first attempt at utterance.
From these considerations we may conclude that our exterior life,
to allow myself the expression, is learnt, and requires before it
can be perfected, a sort of apprenticeship.
IV. _Of the influence of society over the education of the organs
of the animal life._
Over this sort of education, which the organs of the animal life
receive, society exercises a very great influence; it enlarges
the sphere of action of some of them, lessens it for others, and
modifies it in them all.
I shall first remark, that it constantly gives to some of the
organs a perfection greater than naturally should be their
portion. Such in fact is the nature of our occupations as always
to require the especial action of some one, or other of these
organs. The ear of the musician, the palate of the cook, the brain
of the philosopher, the muscles of the dancer, and the larynx of
the singer, receive in addition to the general education of the
exterior life, a particular education.
Under these considerations, the occupations of mankind might be
divided into three classes. The first would comprehend all those,
which especially regard the senses, such as painting, music, and
sculpture, the acts of the perfumer and the cook, and in a word
all those the results of which are productive of pleasure to the
senses. In the second would be ranged the occupations, wherein the
brain is chiefly called into action; such as poetry, the sciences
of nomenclature, the mathematics and metaphysics. The occupations
of dancing, equitation, and the mechanic acts would form the third
class.[46]
Each several occupation then of the individual, brings into
permanent activity, some one organ in particular, and gives it a
peculiar perfection. The ear of the musician in a piece of harmony,
and the eye of the painter in a picture, distinguish many things
which entirely escape the vulgar. It frequently happens that this
perfection of action, is accompanied in the more exercised organ
with an excess of nutrition: this we may frequently observe in the
muscles of the arm of the baker, in those of the inferior limbs of
the dancer, and in those of the countenance of the player.
In the second place I have asserted that society contracts the
sphere of action, which should naturally belong to many of the
external organs. Indeed, for the sole reason that any one of
them is the more occupied, the others must be less so, and lose
in aptitude what is gained by the single organ. The most common
observation will prove this truth at every moment.
Examine the philosopher, who in his abstract meditations, and in
the silence of the closet condemns to inaction his external and
locomotive powers. Examine him by chance attempting any exercise
of the body, and you will laugh at his awkwardness and air of
constraint; his sublime conceptions astonish, the heaviness of his
movements is amusing.
Examine on the contrary the dancer, who by the lightness of his
steps exhibits apparently to the eye whatever the graces of fable
have set before the imagination. It might be imagined perhaps
that the profoundest meditations, have been productive of such
felicity of motion; but let him be conversed with, and nothing very
surprising will be found in the man.
The observing mind, which analyses the different individuals of
society at every moment, will be led to similar remarks. Perfection
of action in the locomotive organs, concurring with a like
perfection of intellect, will seldom be found.
V. _Of the laws, which regulate the education of the organs of the
animal life._
It is manifest then that society inverts the natural order of
education in the animal life, and that it irregularly distributes
to the different organs of this life, a perfection which they would
otherwise enjoy in a more uniform proportion.
A determined sum of power, has been attributed to every individual,
which sum must always remain the same, whether it be equally or
unequally distributed, accordingly the activity of one organ must
imply more or less inactivity in the others.
This truth will conduct us to the fundamental principles of all
social education whatever; namely, that no individual at the same
time, should be applied to many studies, even if it be wished
that he should succeed in all of them. Philosophers have long
insisted upon this maxim, but I doubt whether the moral reasons
on which they have founded it, are all of them together worth
this single and beautiful physiological observation by which it
is demonstrated, that for the purpose of augmenting the powers
of one organ, there are no other means than those of diminishing
the powers of the others. On this account I shall dwell upon this
observation, and prove its truth by a variety of facts.
The ear, and especially the touch, acquire in the blind man, a
perfection which would hardly be credited, were not its reality
proved by daily observation. The deaf and dumb possess in the eye
an accuracy of sight, which is unknown to those, with whom the
powers of the ear and utterance are unfolded. Little connexion with
external objects, enfeebles the senses of persons who are subject
to ecstasy, but gives the brain a power of contemplation, such as
to make it appear, that every part of the animal life, excepting
that organ, during such affection is in a state of sleep.
But what occasion is there for seeking in extraordinary facts, the
proof of a law which the animal in its healthy state exemplifies at
every moment. Let us consider in the series of animals the relative
perfection of each organ, and it will be seen at once, that where
any one of them is excellent, the others are less perfect. The
eagle, which has a very piercing sight, has but a very obtuse
sense of smell; in the dog, the latter sense is extremely fine,
the former dull. The sense of hearing is particularly acute in the
hare, that of touch in the bat; the cerebral action predominates in
the monkey, and vigour of motion in the feræ.
Every species then possesses some particular division of its animal
life, in a degree of excellence superior to that of the others. Not
a single instance will be found, where the perfection of one organ
does not appear to be acquired at the expense of the others. Man
in general, abstraction being made of every other consideration,
has the ear particularly good, and in the natural order of things,
this must be so; because his speech, which exercises the ear
incessantly, is for this organ a permanent cause of activity, and
therefore of perfection. And not only in the animal life is this
law remarkable; but it appears to have place also, in all the
phenomena of the organic life. The morbid affection of one of the
kidneys, of one of the parotid glands, will double the secretion of
the other.
Let us now examine what happens in the process of digestion.
Each system at such time is the seat of an exaltation of the
vital powers. Immediately after the entry of the aliments into
the stomach, the action of all the gastric viscera is augmented,
the powers of life are concentrated about the epigastrium, and
abandon the organs of the external life; from thence arise, as
authors have observed, the lassitude, the inaptitude of the senses
to the reception of external impressions, the tendency of the
individual to sleep, and the cold which is so frequently felt in
the integuments.
The gastric digestion being completed, the vascular succeeds, and
the chyle is introduced into the circulatory torrent, for the
purpose of undergoing the influence of this system, and that of
respiration; accordingly the blood-vessels and lungs become in
their turn, the focus of an increased action, the pulse rises, and
the movements of the thorax are precipitated.[47]
It is then the glandular, then the nutritive system which enjoy a
marked superiority in the state of their vital powers. Lastly, when
these powers have been successively developed, over all the system,
they return to the organs of the animal life, the senses resume
their activity, the functions of the brain their energy, the
muscles their vigour. Whoever reflects upon what he has experienced
after a somewhat copious repast, will be easily convinced of the
truth of these remarks.
In this way, the whole of the functions represent a species of
circle, of which the one half belongs to the organic, the other to
the animal life, the vital powers seem successively to traverse
these two halves. When they are found in one half, the other is
proportionably deprived of them, nearly in the same manner as every
thing appears to languish and be reanimated in the two portions
of the globe, accordingly as the sun refuses, or sheds down his
beneficent influence.
Should any farther proof be required of this inequality of
distribution with regard to the vital powers, we may find it in the
process of nutrition. This process has always an excess of action
in some one of the organs, which at such time may be said to live
more than the others do. In the fœtus, the brain and the nerves,
the inferior members after birth, and at the age of puberty, the
genital parts and breast appear to grow at the expense of the
others.
From such a variety of considerations, we may establish the
following to be a fundamental law of the distribution of the vital
powers, namely, that when they increase in one part, they decrease
in the rest of the living œconomy, that the sum of them can never
be augmented, and that they only transfer themselves successively
from one organ to another. By the help of these general data,
it is easy to perceive why we cannot at the same time attain to
perfection in the various parts of our animal life, why we cannot
at the same time excel in all the sciences.
Universality of knowledge in the same individual is a chimera;
it is repugnant to the laws of our organization, and if history
afford us some few instances of extraordinary men, who have thrown
an equal light upon many of the sciences, such instances are but so
many exceptions to the common laws of nature; for who are we, that
we should venture on the pursuit of many things at once, and hope
to attain in all of them a perfection, which for the most part,
even when we have but a single object in view, escapes us?
Were we capable of following at once a number of occupations,
such occupations would be those which have the greatest analogy
among themselves with respect to the organs which they bring into
exercise: and by restraining ourselves in this way within a narrow
circle, we may, indeed, with a greater degree of facility excel in
many parts; but even here the great secret of being superior in any
one of them, is that of possessing but a mediocrity in the others.
Let us take, for example, the sciences, which bring into action
the functions of the brain. We have seen that these functions
relate especially to the memory, which presides over nomenclature;
to the imagination, under the empire of which, is poetry; to the
attention, which is chiefly excited by the details of calculation;
and to the judgment, whose dominion embraces the whole of the
sciences of reasoning. Now it is manifest from daily observation,
that not one of these different operations of the mind is to be
developed but at the expense of the others.
The habits of reciting the beauties of Corneille or Racine, we
might naturally suppose would enlarge the mind of the actor; what
can be the reason that from such habit he does not acquire an
energy of conception beyond that of the vulgar? The reason depends
in part, no doubt, upon the natural disposition of the man, but at
the same time may be deduced from the greater efforts of memory,
and the faculty of imitation, which such a person is obliged to
exert: for the purpose of enriching these, the other parts of the
brain are in a manner plundered.
Accordingly, when I perceive an individual, desirous at the same
time of excelling by address of hand, in the operations of surgery,
by depth of judgment in the practice of medicine, by extent of
memory in botany, and by force of attention in metaphysical
contemplation, methinks I see a physician, who, for healing a
disease, for the purpose of expelling, according to the old
expression, the morbific humour, at the same time undertakes to
augment the whole of the secretions by the simultaneous use of
sialagogues, diuretics, sudorifics, emmenagogues, &c. &c.
But would not the slightest acquaintance with the laws of the
economy, suffice for hinting to such physician, that one gland
pours forth a greater quantity of fluid, only because the others
secrete a less? Should he not know that such a variety of medicines
can operate in no decided way, and that to exact too much of
nature, is frequently the means of obtaining nothing? The same
may be asked of the individual who is desirous of simultaneous
perfection, both in the bodily and mental exercises, who should
pretend to double or triple his relative life, when nature has
willed that he should only have the power of detaching from some
few of his organs, some few degrees of force, which may be added to
one or more of his other organs, and by no means that of increasing
the sum of these powers.
Do we wish that any one organ in particular shall attain to
perfection, we must condemn the others to inaction. We castrate
men to change their voices; it is astonishing that the barbarous
idea of depriving them of sight has not been found out also for
the purpose of rendering them musicians, since it is well known how
acute the sense of hearing is in the blind. The child, who should
be destined to music, ceteris paribus, would make a much more rapid
progress, were his ears to be assailed by harmonious sounds only,
and every thing removed which might be capable of exercising his
other senses.
It is a truth, then, that our superiority in such or such an art
and science, may almost always be measured by our inferiority in
other respects; and that this general maxim which the greater
number of the ancient philosophers have insisted on, but which many
of our modern ones would willingly overturn, has for its foundation
one of the great laws of the animal economy, and will ever be as
immutable as the base on which it rests.
VI. _Of the education of the animal life as to duration._
The education of the organs of the animal life, is prolonged for
a time which we cannot determine, as it is influenced by such a
variety of circumstances; but the peculiarity of this education
consists in its being the business of each age, to bring to
perfection certain organs in particular.
In childhood, the senses more especially are educated; every thing
seems to relate to the development of their functions. Environed
with bodies which are new to him, the little individual seeks to
know them all; he maintains in a sort of perpetual expectation
those organs by which his connexions with what is near him are
established, and undoubtedly his sensibility is excessively
developed. His nervous compared with his muscular system, is
proportionally very great; accordingly for the dissection of the
nerves, we always prefer the bodies of children.
With the education of the senses, the improvement of the functions
of the brain which relate to sensation is necessarily connected. In
proportion, then, as the sum of the sensations becomes enlarged,
the memory and imagination begin to come into play. The age which
follows infancy, is that of the education of those parts of the
brain in which these faculties are seated.--It is then, that there
have existed a sufficient number of antecedent sensations for the
exercise of the memory, and for the discovery of the type of those
illusory sensations which it is the business of the imagination to
assemble. On the other hand, the little activity of the judgment at
this epoch is much in favour of the energy of these two faculties;
and then the revolution which puberty brings on, the taste which it
develops, and the desires which it creates, contribute very much to
extend the sphere of the latter of them.
When perception, memory, and the imagination have been perfected,
when their education is finished, that of the judgment commences,
or rather becomes more active, for the judgment begins to be
exercised upon the very first materials, with which it is
presented. At this epoch the functions of the senses, and partly
those of the brain have nothing more to acquire, and all the powers
of the individual, are concentrated upon the education of the
judgment.
Hence it is manifest, that the first portion of the animal life, or
that by means of which we are acted on from without, and reflect
such action, has at each age a division, which is then particularly
unfolded. The first age is that of the education of the senses, the
second that of the enlargement of the imagination, the third that
of the development of the judgment.
We should never then prescribe the study of the sciences, which
exact the exercise of the judgment, at an age when the senses are
especially in action; but follow in our artificial methods of
education, the same laws which preside over the natural education
of the organs. The child should be applied to music and design;
the adolescent, to the sciences of nomenclature, and the belles
lettres; the adult, to the exacter sciences, where facts are
connected by a process of reasoning. The study of logic and the
mathematics, terminated our ancient plan of education; it was one
advantage at least among its numerous imperfections.
As to the second portion of the animal life, or that by means of
which the animal reacts upon external bodies, the state of infancy
is characterized by the number, the frequency, and feebleness
of its motions; adult age by their vigour; and adolescence by a
mixture of the two. The voice, however, does not appear to follow
these proportions, but is subject to an influence which proceeds
especially from the organs of generation.
I shall not dwell upon the different modifications, which with
respect to the animal life are derived from sex, climate, and
season. So many have treated of these questions, that it would be
difficult to add to what has been said upon them.
In speaking of the laws of education, as they affect the organs of
the external life, I have supposed these organs to be in a state
of complete integrity, and possessed of whatever is necessary to
their perfection.--If they be feeble or delicate, if any defect
of conformation exist in them, these laws will only be applicable
more or less; for it is manifest that the habit of judging will
not rectify the judgment, if the brain be badly constituted; and
that the frequent exercise of the larynx and voluntary muscles,
will never make up for the irregularity of action occasioned by
irregularity of conformation.
FOOTNOTES:
[41] It is unfortunate that Bichat makes use of the word density,
as he seems to be ignorant of its true signification.
The resistance, which the womb offers to the fœtus that strikes
against it, is wholly independent of density, and results only from
the greater or less flexibility of its parietes. Cork is much less
dense than mercury, and yet it offers to the finger, when pressed
against it, a much greater resistance.
[42] Of these four sources of sensation, the first, whatever Bichat
may say, exists in the fœtus before birth, and the other three, do
not exist some hours after; the eye is insensible to light, the ear
to sound, and the taste is not really in exercise when the first
food creates in the organ an unaccustomed sensation.
[43] Philosophers and physiologists accord to the touch a great
preeminence over the other senses. The senses of seeing, smelling
and hearing are, say they, the sources of a thousand illusions.
The touch alone is exempt from them, and even rectifies the errors
which come from elsewhere; _the touch is the sense of reason_.
It is undoubtedly a delightful prerogative; but let us see if
it is incontestable. And first does the touch never deceive us?
All children know an experiment which proves the contrary. If
we cross two fingers of the same hand, and place in the angular
space between their extremities a small body which touches both of
them, the touch will give the sensation of two distinct bodies.
It is then true that the touch may become a cause of errors; it
no doubt serves to rectify those of the other senses, but do not
these in their turn often defend us from the errors of the touch?
If the sight were not almost constantly in exercise, the errors of
touch would be much more numerous; we can judge of them by what we
experience when we are in the dark. If we were to take from one man
the use of his eyes, and from another that of his hands and the
exercise of touch as much as possible, we should see which would be
the most embarrassed, which would make the most false judgments.
[44] This assertion is not correct, and the voice, at the earliest
age, has consonances peculiar, not only to the species, but even to
the individual. The man accustomed to the very striking differences
of the articulate sounds of speech or the distinct sounds of music,
distinguishes with difficulty the differences in cries; but the
animals to whom the cry is the habitual medium of expression are
not deceived in the same way; the ewe, in the midst of a whole
flock, distinguishes the voice of her lamb, and this soon learns to
recognize the voice of its mother.
[45] The locomotive organs do not require a long education; as we
see in animals whose organization, at the moment of birth, is no
obstacle to motion. A young kid in an hour after, will stand on its
legs, and before the end of the day we often see it skipping. The
partridge runs as it comes out of the shell.
[46] The idea of classifying human occupations, according as
they bring in play the organs of the senses, the intellect or
locomotion, is a wild and useless one. This division besides is
made in a way altogether defective, since in the first class it
is the result of the occupations which put in play the organs,
whatever may be the means of execution; in the second it is the
occupation itself, whatever may be the results, and in the third,
it is at the same time the execution and the result.
[47] We know that at a certain period of digestion the pulse rises
and respiration is accelerated; we know it, I say, but we do not
know the immediate causes of the phenomenon. Is it a reason, in
fact, because a little chyle enters the lacteal vessels that the
heart should accelerate the course of the blood in a system of
vessels entirely distinct from these? Because afterwards this
chyle, mixed in a small proportion with the venous blood, goes with
it through the lungs, is it a reason that the motions of the lungs
should be accelerated? Undoubtedly not; besides, the acceleration
is not successive in these two functions, as Bichat seems to imply.
The one is the necessary and immediate consequence of the other.
But why does the action of the heart increase in this second period
of digestion? We cannot tell; nor do we know why it diminishes in
the first; for to think of explaining it by saying that the vital
forces are then concentrated at the epigastric region, is a mere
illusion; it is only changing the expression of the phenomenon, and
clothing it in a hypothetical form.
CHAPTER IX.
OF THE ORIGIN AND DEVELOPMENT OF THE ORGANIC LIFE.
We have just now seen that the animal life, which is inactive in
the fœtus, is developed after birth: we have also followed up the
particular laws of its development. On the contrary, the organic
life comes into action almost as soon as the fœtus is conceived;
for as soon as the least organization is apparent, the little heart
will be seen protruding its blood on all sides. The heart is the
first formed part, the first in action: now, as all the organic
phenomena depend upon it, we may readily conceive in what way the
functions of the inward life are thrown into exercise.
I. _Of the mode of the organic life in the fœtus._
Nevertheless, the organic life of the fœtus, is not the same as
that which the adult is destined to enjoy. Let us enquire into the
reason of this difference.
We have said that the organic life is the result of two great
orders of functions, of those namely of assimilation and
decomposition, so as to form an habitual circle of creation and
destruction. Now in the fœtus this circle is singularly contracted.
For in the first place, the functions of assimilation are much
fewer in number; the molecules before they arrive within the
organs which they are destined to create, are not submitted to so
many actions; they penetrate the fœtus already elaborated by the
digestion, circulation, and respiration of the mother. Instead of
traversing the apparatus of the digestive organs, which at this age
appear to be almost inactive, they enter at once into the system
of the circulation; the road which they have travelled is less, it
is not requisite that they should be presented to the influence
of respiration; and accordingly the fœtus of the mammalia has in
its preliminary organization a near analogy with that of the adult
reptile, in which but a small part of the blood at its issuing from
the heart, is sent into the vessels of the lungs.[48]
The molecules of nourishment in this way pass almost directly from
the circulating torrent into the nutritive system. The general
process of assimilation, then, is much less complicated than that
of the following age.
On the other hand, those functions which habitually decompose
the organs, which clear the system of substances already become
injurious and foreign to its nature, are at this age but very
inactive. Neither the pulmonary exhalation, nor sweating, nor
transpiration have as yet commenced: the bile, urine, and saliva
are but small in quantity, if compared with what they are destined
at a future time to be, so that the portion of blood from which
they are to be made in the adult, in the fœtus is almost entirely
expended on the system of the nutritive organs.
The organic system of the fœtus, then, is remarkable--on the
one hand, for the extreme promptitude of its assimilation, a
promptitude depending on the very small number of the functions
concurring to that end; and on the other, for the extreme inertia
of its decomposition, an inertia depending on the little activity
of the different functions, which are the agents of this great
process.
It is easy from the foregoing considerations to account for the
rapidity which characterizes the growth of the fœtus; a rapidity
which is manifestly out of all proportion with that which takes
place at any other age. Indeed, while every thing is in favour of
the progression of the nutritive matter towards the parts where
it is destined to be put down, every thing at the same time seems
to oblige such matter to remain in the place where it has been
deposited, the emunctories of the system being wanting.
To the great simplicity of assimilation in the fœtus, we may
add the great activity of the organs which contribute to it
an activity, which depends upon the more considerable sum of
vital power which they then partake. All the powers of the
economy, indeed, appear to be concentrated upon the system of the
circulation and nutrition; the functions of digestion, respiration,
secretion and exhalation, are exercised but obscurely.[49]
If we now observe that the organs of the animal life, which are
condemned to a necessary inaction, are the seat at the same time of
a very small portion only of vital power (the surplus of this being
thrown upon the organic life) it will be easy to perceive, that
almost the whole of the powers which are afterwards to be developed
upon the two systems in general, will be then concentrated upon
those which serve to nourish and compose the different parts of the
fœtus, and that in consequence the functions which concur to the
process of nutrition and growth, must at that age be the seat of an
extreme energy.
II. _Development of the organic life after birth._
Immediately after birth, the organic life of the child has a great
addition made to it; its extent is almost doubled, for not only
are many of the functions which did not before exist at such time
added, but those which existed previously are much enlarged. Now in
this remarkable revolution of things, a law directly the contrary
of that which presides over the animal life is observed; for the
organs of this life, whether they be newly brought into exercise,
or simply receive an increase of action, need no education; they
suddenly attain to a perfection, which those of the animal life do
not acquire, otherwise than by long habitude. A rapid glance upon
the development of this life, will be sufficient to convince us of
the truth of the above observation.
At the instant of birth, digestion and respiration, with a great
part of the exhalations and absorptions commence. Now after the
first inspirations and expirations; after the elaboration in the
stomach of the first milk, which is taken in by the infant, as soon
as the exhalants of the lungs and the skin have once rejected some
small portions of their respective fluids, the respiratory, the
digestive and exhalant organs, have as perfect an action as they
ever will have.
At the same time all the glands, which slept as it were, which
poured forth but a very small quantity of fluid, are awakened from
their torpor by the stimuli of the various substances which are
applied to the mouths of their excretory ducts. The passage of
the milk at the extremities of the stenonian and wartonian ducts,
of the chyme at the end of the choledochus and the pancreatic
duct, the contact of air with the orifice of the urethra, awaken
into action the salivary glands, the pancreas, the liver, and
the kidneys. The air in like manner upon the inner surface of
the trachea and the nostrils, and the aliments upon that of the
digestive passages, are the excitants which rouse these parts into
action.[50]
It is then also that begin the various excretions of the system:
now if we examine well the different organs which concur to the
above mentioned phenomena, we shall find that they require no sort
of education.
I shall not inquire into the reason of this difference in the
development of the two lives. I shall only observe that it is out
of the power of any one of the inward organs, to acquire a marked
degree of superiority over any other, for the same reason that they
all of them attain, immediately upon entering into action, as great
a perfection as at any time they are destined to possess.
Nevertheless there is nothing more common than the predominance
of one system of the organic life over the other systems; this
is sometimes the vascular, sometimes the pulmonary apparatus, at
other times the organs of digestion, and the liver especially, have
the greater degree of development, and decide on the particular
temperament of the individual; but the cause of this sort of
constitution depends on primitive organization, on the structure
of the parts, on their conformation. Such superiority is by no
means the effect of exercise or habit, for the fœtus and the
child display the same phenomena, in as much reality though less
apparently indeed, than adolescence, or manhood.
In the same way, the debility of any particular system of the
internal functions, may depend either on original constitution, or
on some accidental vice or disease, by which, while the others
have remained untouched, its constitution may have been impaired.
Such then is the great difference of the two lives of the animal,
with respect to inequality of perfection in the organs. In the
animal life, the predominance or inferiority of one system, with
relation to the others, depends almost entirely upon its activity
or inertia, on its habitude of acting or not acting. In the organic
life on the contrary, such states are immediately connected with
the texture of the organs, and never with their education.
From hence also we have the reason why physical temperament, and
moral character, are not susceptible of change from education,
which so prodigiously modifies the actions of the animal life, for
as we have seen, they both of them belong to the organic life.
The character is, if I may so express myself, the physiognomy of
passions; temperament, that of the internal functions: now the
one and the other being at all ages the same, having a direction
which habitude and exercise can never alter, it is manifest that
they must ever be withdrawn from the influence of education. The
violence of the temperament may indeed be moderated, for the powers
of the judgment, and reflection may be augmented, and the animal
life strengthened in such way as to give it a capacity of resisting
the impulses of the organic life; but to attempt an immediate
alteration of the character, or of the passions, which are its
habitual expressions, is an enterprise analogous to that of the
physician, who should attempt to elevate or depress, (and that, for
the entire life of the patient,) the ordinary contracting powers of
the heart and arteries.
We should observe to such physician, that the circulation and
respiration, are not under the dominion of the will; and that they
cannot be modified excepting in passing into a state of disease.
The same observation might be made to those, who imagine that the
character, and consequently the passions may be modified.
FOOTNOTES:
[48] I am persuaded that the still very obscure theory of the
fœtus might be elucidated by that of animals who have a similar
organization. For example, in the frog, in whom but little blood
goes through the lungs, the heart is a simple organ, with a
single auricle and ventricle; there is a communication or rather
continuity between the two systems, venous and arterial, whilst in
the mammalia, the vessels in which the red blood circulates do not
communicate with those which carry the black blood, except it be by
the capillaries.
In the fœtus, the foramen ovale and the ductus arteriosus also
render very evidently the arteries and veins continuous; in
the fœtus the heart is likewise a simple organ, not forming,
notwithstanding its partitions, but one cavity whilst it is double
after birth. The two kinds of blood mix at this period, as in
reptiles. Now, I shall prove hereafter, that in the child who has
breathed, this mixture would soon be fatal; that the black blood,
circulating in the arteries, would very quickly produce asphyxia
in the animal. Whence arises then this difference? It cannot be
studied in the fœtus; it is necessary perhaps to search for it
in frogs, salamanders and other reptiles, which can, by their
organization, be a long time deprived of air without dying, a
phenomenon which approximates them to the mammalia while living in
the womb of the mother. Till these very important researches are
made, the history of respiration will be incomplete.
[49] This explanation is no doubt ingenious, but it is
insufficient, since the causes which Bichat assigns for the
rapidity of the growth of the fœtus cease entirely at the moment of
birth, and yet the growth continues for a long time after to be as
rapid.
[50] When two phenomena are seen to follow each other immediately,
we are naturally led to consider one as the cause of the other.
_Post hoc ergo propter hoc._ It is a form of reasoning which is
very often abused. Food taken into the mouth touches the orifice of
the salivary ducts, the fluid flows out, and it is then concluded
that the salivary gland has been excited by the impression made on
the extremity of its canal. At the moment of birth, the orifice
of the urethra is exposed to the contact of the air, and soon the
kidneys begin to secrete; then it is the impression of the air
on the urethra that has produced their action. But is not this
contact of the food in the one case, and of the air in the other
an accidental and purely accessory circumstance? Do we believe,
that if by any cause the opening of the prepuce was entirely
obliterated, the secretion of urine would be prevented? Do we not
know that if instead of taking into the mouth savoury food, it
is brought near to it, the saliva flows not less, or in vulgar
language the mouth waters? There is however no contact, there is
not any mechanical or chemical impression in the orifice of the
salivary ducts.
CHAPTER X.
OF THE NATURAL TERMINATION OF THE TWO LIVES.
We have just now seen, that the two lives commence at distant
epochs; we have seen them developing themselves according to laws,
which are exactly the reverse of each other. I shall now attempt
to describe them, as they terminate; and this they do in a very
different manner also, assuming characters at such time as distinct
and separate, as those which they possess during the periods of
their activity. In this place, I shall speak of natural death only;
those deaths, which originate in accidental causes, will be the
object of the second part of this work.
I. _In Natural Death the animal life is the first to cease._
Natural death is remarkable for the following reason chiefly:--it
terminates the animal life, a long time before it puts an end to
the organic life.
He who dies in consequence of a very prolonged old age, dies in
detail; his exterior functions are finished, one after the other;
the senses are shut up successively; the ordinary causes of
sensation pass over them, and do not affect them.
The sight grows dull and confused; it ceases at length to transmit
the images of objects: this is the blindness of old age; sounds
also, after a certain time, affect the ear confusedly; the organ
at last becomes entirely insensible. The cutaneous covering of the
body grows hard and dry; it is the seat of an obscure and imperfect
touch. Besides which, the habitude of feeling has blunted the
power of feeling; at the same time all the other organs which are
dependent on the skin, grow weak and perish; the hair falls, it is
deprived of the juices by which it was nourished: to continue our
description, odours make but a feeble impression upon the nostrils.
The taste indeed is a little more kept up; but let it be remarked
that this sense is connected with the organic as much as with the
animal life, and is therefore necessary to the internal functions:
In this way, when all agreeable sensations have fled the old man,
when their absence has already broken in part the connexions, which
attach him to the world, his taste remains with him still; it is
the last thread to which is suspended the pleasure of existence.
In this way, isolated in the midst of nature, already deprived of
the greater number of the functions of the sensitive organs, the
old man is soon to suffer the loss of the common action of the
brain, for it is manifest, that there can scarcely be any farther
perception, for the very reason that there is nothing farther
coming from the senses. Meanwhile, the imagination lessens and is
soon annihilated.
The memory of present things is destroyed: the old man in an
instant forgets what is told him, because his external senses
enfeebled and already dead, as it were, in no wise confirm what
is intimated to him by the mind alone. Ideas escape him when the
images, which are traced by the senses, do not keep their hold. On
the contrary, the remembrance of the past remains with him, that
which the old man has formerly known, has been taught him or at
least confirmed to him by his senses.[51]
He differs from the child in this respect; the child judges only
from the sensations which he experiences, the old man from those,
which he has experienced.
The result of the two states is the same, for the judgment is
equally uncertain, whether founded exclusively upon actual or past
sensation. Its accuracy depends upon the due comparison of the two.
No one can be ignorant, that in the judgment which we form from
visible objects, the actual impression would frequently deceive
us, were we not to rectify the error by what we are enabled to
recollect, and may we not observe that past sensations, in a short
time grow confused, if the features of the picture, which they have
left with us, be not retraced by new and analogous impressions?
The present then, and the past with regard to sensation, are
equally necessary for the perfection of the judgment. If either
the one or the other be wanting there cannot be any comparison
made between the two, and in consequence there must be a want of
precision in the judgment.
For these reasons, the first and the latter ages of man, are
equally remarkable for imbecility. Old age is second infancy. The
two periods of life resemble each other with regard to want of
judgment; they differ only as to the cause of such defect.
The interruption of the functions of the brain of the old man,
is a consequence of the almost entire annihilation of the
sensitive system with him; in the same way does the weakness of
the locomotive power, succeed almost inevitably to the inactivity
of the brain. This organ in fact re-acts upon the muscles, in
proportion only as the senses act upon it.
The movements of the old man are few and tardy; he changes with
difficulty the attitude, into which he has thrown himself; seated
near the fire, and concentrated within himself, a stranger to every
thing without him, he passes his days there, deprived of desire, of
passion, and sensation; speaking little because he is determined by
nothing to break his silence, yet happy in feeling that he still
exists, when almost every other sentiment is gone.
The rigidity of the muscles however, and the diminution of their
contracting powers, is another cause of inactivity in the old
man, and doubtless has its influence; but it is by no means the
principal one, since the heart and the muscular fibres of the
intestines, contract the same rigidity, and are deprived of their
powers of moving, in a very different way from that, in which the
voluntary muscles lose it. With the voluntary muscles, it is not
so much the power as the excitant of the power which is lost. If
it were possible to compose a man with the senses and brain of old
age, and the muscles of youth, the voluntary motions of such man,
would hardly be more developed for the reasons which I have given.
From the above it is easy to see that the external functions of
the old man are extinguished by degrees, and that his animal life
has almost entirely ceased, while his organic life is still in
activity. Under this consideration, the state of the animal about
to suffer a natural death, is nearly similar to that of the fœtus
in utero, or of the vegetable which lives within itself only, and
for which external nature is absolutely silent.
If we now recollect that sleep entrenches more than a third upon
the duration of the animal life, if we add to this the total
absence of such life for the first nine months of existence, and
its almost entire inactivity during the latter period of existence,
it will be easy to calculate the great disproportion of its
duration, when compared with that of the organic life which is
exercised uninterruptedly.
But wherefore when we have ceased to exist without, do we continue
to exist within, since our sensations and above all, our powers of
locomotion, are especially destined to place us in relation with
those substances, which are to nourish us. Wherefore are those
functions enfeebled in a greater disproportion than the internal
functions, and why is there no exact relation in the times of their
cessation.
I cannot entirely resolve this question. I shall only observe that
society has an especial influence in creating this difference;
for man in the midst of his fellow-creatures makes a very great
use of his animal life; the springs of it are habitually more
fatigued than those of his organic life, and worn away under the
influence of society; the eye by artificial light, the ear by
sounds too frequently repeated, and above all by those of speech,
which are wanting to other animals;[52] the smell in like manner
is debilitated by factitious odours, the taste by savours, which
certainly are not natural, the touch and the tact by constant
attrition of dress,[53] and the brain by too incessant thinking.
We live then externally with excess. We abuse our animal life;
it is circumscribed by nature within limits which are too much
enlarged by us for its duration; thus it cannot be surprising that
it should cease so soon. In fact we have seen the vital powers
divided into two orders, the one appertaining to this life, the
other to the organic life. These two orders may be compared to
two lights which burn at the same time, and which have only a
determined quantity of materials for aliment. In which case, if
the one be agitated by a stronger wind than the other is, it must
necessarily be the sooner extinguished.
Yet social influence notwithstanding is very advantageous to man.
It gradually disengages him from those bonds which attach him to
life, and renders the instant of death less terrible.
The idea of our last hour, is painful only because it puts an end
to our animal life. The borders of the tomb are beset with terrors,
which will all be found to originate in the thought of such
privation.
It is not the pain of death, which we fear; how many dying men
are there for whom the gift of existence would be precious, though
purchased at the expense of an uninterrupted series of suffering!
If we look at the animal which lives but little externally, he by
no means trembles at beholding the instant of his death.[54]
Were it possible to suppose a man, who in dying should lose his
internal functions only, such man would look upon his death with
an indifferent eye, because he would feel that the blessings of
existence, are attached to the powers of feeling the influence of
nature and society.
If the animal life then be terminated gradually, if each of the
bonds by which we are capable of the pleasures of living, be broken
by little and little, such pleasures will escape us imperceptibly,
and the old man will have forgotten the value of life, when it is
about to be taken from him; such destruction will resemble that of
the vegetable only.
II. _The Organic Life in natural death does not terminate as it
does in accidental death._
The organic life remains with the old man after the almost total
loss of his animal life, and terminates in a very different manner
from that which is exemplified in the case of violent and sudden
death. The latter has two periods, the first of which is marked
by the sudden cessation of respiration and the circulation, the
second by the slow and gradual extinction of the other organic
functions.
The parietes of the stomach, for instance, continue to act upon
the aliment which may be found there, the juices of the stomach
continue to dissolve it. The experiments of the English and Italian
physicians upon absorption, (experiments the whole of which I have
repeated) have proved that this function not unfrequently remains
in a state of activity, after the general death of the body, and if
not as long as some have supposed, at least for a very considerable
interval. Discharges of urine and feces are often observed to take
place many hours after sudden death.
The process of nutrition also continues to be manifest in the hair
and in the nails; the same would doubtless be the case in all the
other parts, as well as in the secretions, could we observe the
insensible movements of which their functions are the result. The
heart of the frog being taken away, the capillary circulation may
still be seen under the influence of the tonic powers. The body is
very slow also in losing its animal heat.[55]
I might augment the above observations with a number of others,
which would go to prove the same assertions; on the contrary,
in the death which is the effect of old age, the whole of the
functions cease, because they have each of them been successively
extinguished. The vital powers abandon each organ by degrees,
digestion languishes, the secretions and the absorptions are
finished, the capillary secretions become embarrassed; lastly, the
general circulation is suppressed. The heart is the ultimum moriens.
Such, then, is the great difference which distinguishes the death
of the old man, from that which is the effect of a sudden blow. In
the one, the powers of life begin to be extinguished in all the
parts, and cease at the heart; the body dies from the circumference
towards the centre: in the other, life becomes extinct at the
heart, and afterwards in the parts. The phenomena of death are seen
extending themselves from the centre to the circumference.
FOOTNOTES:
[51] If the old man preserves with difficulty the memory of the
most recent events, whilst he often retraces with the greatest
ease the recollection of the most distant ones, it is not because
the first have been more faithfully transmitted to him by his
senses, but because these events had produced a greater impression
on him. This is so true, that failure of the memory is sometimes
remarked in old people who have their senses in perfection. On the
other hand, very imperfect sensations may produce a very lively
impression. A connoisseur in painting, when his sight is very bad,
experiences in seeing a beautiful picture, a hundred times more
pleasure, than one who is indifferent to it, though he examines it
with good eyes, and the connoisseur preserves the image of it long
after the other has lost it. We do not perceive the recollection of
things, unless there is some circumstance connected with them that
makes a lively impression; but in the same event, this circumstance
will not be the same in all individuals, and it is sometimes by the
most trifling of all that a man fixes the fact in his memory.
[52] This failure of the senses appears in animals as well as
man, and it may be observed in those whom we suffer to grow old
among us. We often see dogs becoming blind and deaf; and these
infirmities are perhaps more common in them than in man. But as
these animals are rarely permitted to arrive at extreme old age, we
have not often an opportunity of observing them.
[53] By defending the skin from the shock of external bodies, and
by preserving it from the variation of temperature, dress very
certainly preserves its sensibility, and far from impairing the
sense of touch, as Bichat maintains, it acts as a circumstance
favourable to its preservation.
[54] The animal no doubt does not tremble at the moment of death;
for he does not see it. His present sensation is every thing to
him. If he suffers at the approach of death, he shows it by the
usual signs; but it is only the present pain that he expresses,
he sees nothing beyond. The child is in this respect, in the same
situation as the animal.
[55] In order to ascertain the cause of the differences in the
cooling of the body after the various kinds of death, it is
necessary to examine what general conditions can have an influence
in the cooling of a body left to itself. Of these there are three
principal ones.
Under the same external circumstances, a body will cool so much the
slower. 1st. As its temperature at the beginning of the experiment,
shall be higher in relation to that of surrounding bodies; 2d. As
its surface shall be less in relation to its size; 3d. And as its
exterior parts shall be less perfect conductors of heat.
In order to see how the first condition is modified in different
cases, it is necessary to recollect what is the source of animal
heat. The blood is warmed in passing through the lungs in
consequence of the chemical phenomena of respiration; and as from
the lungs it is carried to all parts of the body, it yields to the
different organs a portion of the heat which it has received. Hence
the general temperature of the body will be higher in proportion
to the temperature of the blood, to the frequency with which this
fluid is renewed in the organs and to the quantity of it that is
brought to them, at each pulsation.
Now in diseases of long duration, the volume of blood is
considerably diminished, the activity of the heart is lessened,
and respiration is performed in an imperfect manner. Thus the body
of the patient who sinks under these circumstances has less heat
to lose than that of the man who dies suddenly, when all these
functions were performed in perfection.
Let us pass now to the second condition. The cooling, as we have
said, takes place so much the quicker as the surface of the body is
the more extended in proportion to its size; now, in the emaciation
which accompanies almost all diseases that are protracted, the size
decreases much more rapidly than the surface. Thus then, when even
at the moment of death the general temperature of the body may be
as high as in a state of health, the cooling would however take
place more quickly.
It remains for us now only to examine under what circumstances
the third condition is fulfilled in the most advantageous manner.
When an individual in full health dies, the sub-cutaneous cellular
texture usually contains a greater or less quantity of fat. Now we
know that it is one of the characters of all fat substances to be
very bad conductors of heat. Hence then a third reason which should
render cooling more slow after sudden deaths. Sometimes after a
disease, this last condition is fulfilled in another manner. In
certain derangements of the circulation, the cellular texture is
filled with serum; and as all aqueous fluids are bad conductors of
caloric, though the temperature of the body may not be very high at
the moment of death, the heat is yet preserved for a long time.
To the different causes which we have just mentioned, there is
sometimes added another which is peculiar to one kind of sudden
death. It is observed that in the midst of the same external
circumstances, the blood does not always cool with the same
quickness, and that in proportion as its coagulation is slower,
its heat is longer preserved. Now, it is a well known fact, that
when death is the result of asphyxia, the vessels are found full
of fluid blood; this is also a reason which contributes to explain
the slowness of the cooling. And it should be remarked, that
asphyxia is one of the most frequent causes of sudden death either
accidental or voluntary.
BICHAT ON LIFE AND DEATH.
PART THE SECOND.
CHAPTER I.
GENERAL CONSIDERATIONS ON DEATH.
In the first part of this work, I have explained the two great
divisions of life, together with the remarkable differences, which
distinguish the animal existing without, from the animal existing
within. I have discussed the characters which are exclusively
proper to the two lives, and the particular laws, according to
which they both of them commence, are developed and end in the
natural order.
In this second part I shall inquire in what way they accidentally
finish, in what way their course is prematurely arrested.
The influence of society suffers us but rarely to live out the
period which was intended us by nature; while almost every other
animal attains his natural end, such end in the human species is
become a sort of phenomenon. The different kinds then of accidental
death, should engage the particular attention of the physician
and physiologist. Now this sort of death may happen in two ways:
sometimes it is the result of great disturbance excited in the
economy; and sometimes it is the effect of disease.
In general it is easy enough to discover, according to what laws
the functions are terminated in consequence of any violent or
sudden attack; of apoplexy, for instance, great hemorrhagy,
concussion of the brain, or asphyxia; because in such cases the
organs of the body, excepting that which is immediately affected,
are not the seat of any peculiar lesion, and cease to act from
causes diametrically the contrary of those, which according to
the common course of things maintain them in action. Now as these
causes are partly known, their contraries may be inferred; besides,
we are capable of imitating these sorts of death upon animals,
and consequently of analyzing, experimentally, their different
phenomena.
On the other hand it is seldom in our power to produce artificially
in the bodies of animals the diseases of the human species. Were we
even possessed of such power, we should gain but little knowledge
from it: the laws of life in fact are so changed, so modified, so
altered in their very nature, by the various morbid affections to
which the parts are subject, that but very seldom can we depart
from the known phenomena of the living animal, when we undertake to
inquire into those which it exhibits in its dying moments. For such
inquiries it would be necessary to know what is that intermediate
state between health and death, in which the functions experience
so remarkable a change; a change, which has such infinite
varieties, and produces such innumerable sorts of disease. But,
where shall we find the physician, who will assert that from the
actual data of his art, he understands in such intermediate state,
the profoundly hidden operations of nature?
In these researches then, we shall occupy ourselves more especially
on those sorts of death which I first enumerated. Those, which have
been mentioned in the preceding paragraph will engage us only now
and then: besides, at my age I cannot be supposed to have acquired
a sufficient degree of medical knowledge to treat of them with
advantage.
The first remark, which the observation of the different kinds of
sudden death suggests, is, that in all of them the organic life to
a certain point may subsist, the animal life being extinct; but
that the latter is entirely dependent, and lasts not for a moment
after the interruption of the former. The individual, who is struck
with apoplexy may live internally for many days after the stroke,
externally he is dead. In this case death commences with the animal
life: if on the contrary it exerts its influence in the first place
upon any of the essential organic functions--as on the circulation
in wounds or on respiration in the asphyxiæ--the animal life is
gone at once, together with the sensible actions of the organic
life.
The red and warm-blooded animal, loses his external life at the
moment when he ceases to exist internally, the cessation of the
phenomena of his organic life is a sure index of his general death;
indeed the reality of death can be pronounced only from such datum;
the interruption of the external phenomena of life is in almost
every instance fallacious.
On what depends this difference of the manner in which the two
lives accidentally end? It is owing to the mode of that influence,
which they exercise the one over the other, to the kind of bond, by
which they are connected.
This mode of influence, this bond, appears to exist between the
brain on the part of the animal life and the lungs, or heart on
the part of the organic life. The action of one of these three
organs is essentially necessary to that of the two others; and as
they constitute the three centres, in which are terminated all the
secondary phenomena of the two lives, whenever they cease to act,
the phenomena which depend upon them must cease also, and general
death ensue.
Physiologists have been at all times acquainted with the importance
of this triple focus; and have given the name of vital to all those
functions, which have their seat in it. Under the point of view
which at present engages our attention their ideas on this head are
well worthy of notice, for every species of sudden death begins by
the interruption of the circulation, the respiration, or action of
the brain. In the first place, one of the three functions ceases,
then the others successively; so that to expose with precision the
phenomena of sudden death, we must consider them as they take place
in the three principal organs, which we have mentioned.
We shall first inquire into those deaths, which begin at the heart,
and afterwards into those, which begin in the lungs and in the
brain. I shall explain in what way, when one of these organs is
affected, the others die; and then demonstrate by what sort of
mechanism the death of the various other parts of the body ensues.
Lastly I shall determine from the principles, which I shall then
have laid down, the nature of the different species of disease,
which are peculiar to the heart, the lungs, and the brain.
CHAPTER II.
OF THE INFLUENCE OF THE DEATH OF THE HEART, OVER THAT OF THE BRAIN.
I shall evidently have determined what is the mode of this
influence, should I be enabled to establish in what way the
action of the heart is necessary to that of the brain; for in this
instance the cause of death will be no other than the privation
of the cause of life. Now the heart can only act upon the brain
in two ways; by the nerves, or the vessels which serve as their
connecting medium. In fact these two organs have no other means of
communication.
It is evident that the nerves cannot be the agents of such actions;
it is the province of the brain to act by means of the nerves.
The different parts of the body never influence the brain by such
means, excepting in the sympathies. If a bundle of nerves belonging
to the voluntary muscles be tied, the muscles indeed will cease to
act, but nothing will be changed in the cerebral mass.[56]
I have ascertained by many experiments that the phenomena of
galvanism, which are propagated so energetically from the brain
towards the organs, which descend, if I may so express myself,
along the nerve, will hardly ascend in a contrary direction. Apply
the apparatus to a nerve of the loins and the muscles of the upper
limbs, and when the communication is made, there will be scarcely
any contraction; but on the establishment of a communication
between the same nerve and the lower limbs, a violent convulsive
motion will instantly be occasioned. I have even observed, on
placing two metallic plates, the one under the lumbar nerves, and
the other under the upper limbs, that the communication of the two
plates by means of a third metal, will cause a contraction of the
lower limbs, while the upper limbs remain inactive, or move but
feeble.[57]
These experiments are particularly applicable to the relation of
the heart with the brain; for not only is it true that the section,
ligature or compression of the cardiac nerves are of little effect
with regard to the functions of the latter, but it is true also,
as we shall presently see, that they do not directly modify the
movements of the former. We may conclude that the vessels are the
exclusive agents of the influence of the heart upon the brain.
The vessels, as every one knows, are of two sorts--venous or
arterial--they carry black or red blood, the latter answer to the
left side, the former to the right side of the heart. Now their
functions being very different, the action of one of the portions
of this organ on the brain, can never be the same as that of the
other portion. We shall inquire in what way they both of them act
upon it.
In naming these two portions, I shall not make use of the
expressions of right and left to distinguish them, but of those
of the red-blooded and the black-blooded heart, for each of these
portions of itself is an isolated organ, distinct from that to
which it is applied, and in the adult especially so. In fact there
are two hearts, the one arterial, the other venous, notwithstanding
which, we can hardly employ these adjectives for the purpose of
designating them, since they both alike possess their arterial
and venous appendages. On the other hand, they are neither of
them situated exactly to the right or to the left, are neither
of them exactly forwards or backwards. Besides which these latter
denominations would not apply to animals.
I. _In what way does the cessation of the functions of the
red-blooded heart interrupt the functions of the brain?_
The red-blooded ventricle and auricle, exert their influence upon
the brain by means of the fluid which they send thither through the
carotid and vertebral arteries. This fluid may excite the cerebral
organ in two ways. 1st. By the movement, with which it is directed.
2nd. By the nature of its colouring principle.
It is easy to prove that the movement of the blood is necessary
to the life of the brain. Expose the brain of an animal in part,
and tie the carotids. In such case the cerebral movement will be
sometimes weakened, and then the animal will be stupified, at other
times the vertebral arteries will exactly supply the place of the
carotids, and then there will be nothing deranged in the principal
functions of the brain; for there is always a relation existing
between the alternate rise and fall of the cerebral mass, and the
energy of life which it displays.[58]
In general, the obliteration of the carotids is never suddenly
mortal. Animals will live without them, at least for a certain
time. I have kept dogs in this state for several days and have
afterwards made use of them for other experiments: two however died
in the course of six hours, after the application of the ligatures.
After having made the above experiments which go very far to the
establishment of the principle which I am labouring to prove, let
a piece of the cranium be taken from another animal and tie the
vertebral and carotid arteries. The movement of the brain will then
be entirely interrupted and the animal immediately die.
The impulse, which proceeds then from the influx of the blood into
the brain, is a condition essential to the functions of this organ,
but other proofs may be adduced, for the establishment of the truth
of this assertion.
1st. There are a number of compressions, which can only act by
preventing the brain from being duly affected by such impulse.
A collection of pus, or blood, will often put a stop to all the
functions, which relate to the perception, memory, and voluntary
motions of the individual. Let such compression be removed and
his sensibility will immediately re-appear. In such case, it is
manifest that the brain was not disorganized, but only compressed,
and in a state incapable of being excited by the heart.[59]
I do not think it necessary on this subject to cite cases. All
authors, who have treated of wounds of the head, are full of them.
I shall content myself with remarking, that the same effect may be
artificially produced in our experiments upon animals, and that
accordingly as the brain is compressed or free, the creature will
be insensible, or the contrary. According to the degree of the
compression, will be the degree of the stupor.
2dly. There are reptiles, in the brain of which no motion whatever
is occasioned by the heart. The frog is of this species. On raising
the upper portion of the cranium, and exposing the brain, there
cannot be perceived the slightest motion. Now in this species, and
that of the salamander, the influx of blood may be cut off from
the cerebral organ without occasioning the immediate death of the
animal. The voluntary muscles for instance continue to act; the
eyes to exhibit a lively appearance, the tact also of the creature
is manifest for some time after the heart has been taken away,
or the double branch which proceeds from the single ventricle of
these animals has been tied.[60] I have frequently repeated these
experiments, and have constantly found the effect the same.
3rd. It is a general observation, that those animals which have a
long neck, and in which the heart for that very reason is not so
capable of exerting a lively influence over the brain, have a more
limited intellect, and the cerebral functions less marked. On the
contrary a very short neck, and the approximation of the heart to
the brain very generally are found to coincide with the latter.
Similar phenomena are sometimes observed in men. They who have the
neck particularly long are dull, they who have it short, for the
most part intelligent and lively.
From these many facts we may confidently assert, that one of the
means, by which the heart maintains the brain in action, consists
in the habitual movement, which it impresses on it.
But this movement is essentially different from that which in the
other viscera, such as the liver, or spleen, is derived from the
same cause. In these it is little manifest, in the brain it is very
apparent; the reason is evident; the large arterial trunks of the
brain, are situated at its base, between the brain and its bony
parietes; in consequence of which, at each diastole, the vessels
experience a resistance from the bone, which is communicated
immediately to the cerebral mass. At such time the brain is really
lifted, just in the same way as we see a tumour lifted by the
arteries which creep along the bones beneath it; and instances of
this are frequent. So apparent indeed is the motion of tumours when
they are situated over the carotid, as it lies upon the vertebral
column, or over the femoral artery, immediately after its passage
under the crural arch, as often to occasion doubts with respect to
their nature.
But no other organ is enclosed within a bony cavity; the motion of
the arteries every where else, is lost in the surrounding cellular
substance, or soft parts. Such motion, then, is unessential to the
functions of the liver, the kidney, and other analogous viscera.
The integrity of the functions of the brain, is not only dependent
on the mere motion, but on the sum also of the motion communicated.
It is equally impaired by too much, or by too little motion. Of
this assertion the following experiments are proofs.
1st. Inject water by the carotid of a dog; the presence of this
fluid in the brain is not pernicious, and the animal will live
very well, when the injection has been skilfully made. But if it
be pushed with violence, the cerebral action will immediately be
troubled, and often cannot be restored.[61] In every experiment,
there will be found to exist a relation between the force of the
impulse and the state of the brain; if the pressure be but a little
augmented, its effects will be instantly seen in the agitation
of the countenance of the creature; if relaxed, a corresponding
calm will succeed; if increased to the highest pitch, it will
immediately occasion death.
2dly. If the brain be exposed, and an artery afterwards opened, so
as to produce a considerable hemorrhage, the motion of the brain
will be diminished in proportion as the afflux of the blood to it
is diminished, and finally will cease entirely. Now, according to
all these various degrees of diminution, which may be observed in
the movements of the brain, will be the corresponding weakness of
the cerebral influence as it is discoverable in the state of the
eyes, the touch, and the voluntary motion of the animal.[62]
Hence it is easy to see, why a state of prostration and languor
is always the consequence of great hemorrhage--and from what has
been said above we may conceive the reason, why the arterial system
of the brain has been at first concentrated at its base, while
the larger venous trunks are almost all of them situated on the
convexity of its surface. The base of the brain is small and easily
moved, the convexity large and little capable of transmitting
motion, such as could be made upon it by vessels. Besides, it
is at the lower part of the brain that exist its particular and
essential forms. The lesions of these are mortal, and consequently
their functions must be important. On the contrary, experiment
and observation alike have proved, that very little derangement
follows, from cutting or rending the substance of the upper part
of this organ. Hence also we may see the reason, why its natural
defences towards its base, are constituted in such way as to be
almost impenetrable, and why at its upper surface, it is less
protected. Now, where its life is indispensable, and its action
absolutely necessary, it should naturally receive the first and
undiminished impulse of its excitant. We may conclude, that the
interruption of the action of the red-blooded heart is the occasion
of interruption in the action of the brain by annihilating its
movement.
But this movement is not the only means by which the influence
of the heart is exerted on the brain; for if it were so, we
might easily reanimate the enfeebled functions of the latter, by
injecting it with water at the same time through both the carotids.
If pushed with an equal force, the black blood and the red blood
alike would be capable of keeping up its action; but this, as we
shall presently see, is not the fact.
The heart, then, acts upon the brain by the nature of the fluid
which it sends thither; but as the lungs are the focus, where the
blood undergoes an alteration, we shall refer the examination of
its influence upon the cephalic system, to the chapter in which we
shall treat of the relation of this system, with that of the lungs.
II. _In what way does the cessation of the functions of the
black-blooded heart interrupt the functions of the brain?_
It very rarely happens that general death commences by that of the
venous auricle and ventricle. On the contrary, they are almost
always the last in action, and when they cease to act, the brain,
the lungs, and the red-blooded heart have already ceased to exhibit
their respective phenomena. Nevertheless the contraction of these
cavities may be annihilated, or rendered at least inefficacious
with regard to the circulation, from the rupture of an aneurism or
similar causes; in which case the brain becomes inactive and dies,
as we have shewn it to do in the preceding section, from want of
movement.
There is another kind of death of the brain depending on the
interruption of the transmission of blood from the head to
the heart, as when the jugulars are tied. The venous system,
in consequence, is glutted and the brain compressed, from the
continued afflux of the red blood into its arteries; but the
phenomena of this sort of death are already sufficiently known.
In the present chapter it is my intention to examine a species of
death, the principle of which by many physiologists has been placed
in the heart, but which appears to me to affect the head only; I
mean that death which may be occasioned by the injection of air
into the veins.
It is generally known, that as soon as any quantity of this fluid
is introduced into the vascular system, the movements of the heart
are accelerated, that the creature is much agitated, cries with
pain, is convulsed, and soon after deprived of its animal life, but
lives organically for a certain time, and then invariably dies.[63]
Now, what is the organ so readily affected by the contact of air? I
affirm it to be the brain, and not the heart; and maintain that the
circulation is annihilated, only because the cerebral actions have
previously been so.
For, in the first place, in this kind of death, the heart continues
to beat for some time after the cessation of the animal life,
and consequently for some time after that of the action of the
brain.[64]
Secondly, By injecting air into the brain through one of the
carotids, I have caused the death of the creature just in the same
way as when air is introduced into the veins; excepting only with
a previous palpitation of the heart.[65]
Thirdly, Morgagni has cited a number of cases of sudden death,
the cause of which should appear, from his remarks, to be the
repletion of the blood vessels of the brain by air, which had
been developed there spontaneously, and which he says, by its
rarefaction, compressed the origin of the nerves. I cannot suppose
that such compression can be effected by the very small quantity
of air, which, when injected into the carotid, is sufficient
to occasion death; accordingly, I should doubt whether this
compression were real in the cases adduced, but for this, they are
not the less important. Whatever be the manner in which it kills,
air is fatal whenever introduced into the brain, and this is the
essential point. It is with the fact that we have to do and not the
manner.[66]
Fourthly, As often as an animal is killed by the insufflation of
air into one of its veins, I have ascertained that the whole of
the red-blooded, as well as the black-blooded heart, is full of a
frothy blood, mixed with air bubbles; and that the carotids, and
vessels of the head, contain a similar blood; such blood must act
upon the brain, in the same manner as it does in the two sorts of
apoplexy, of which we have just been making mention.
Fifthly, If air be pushed into one of the divisions of the vena
portæ from the side of the liver, it oscillates in the greater
trunks of that organ for a considerable length of time, and arrives
but slowly at the heart.--In this instance I have observed, that
the animal experiences, only after a certain interval, those
affections which are sudden when the fluid is injected into the
veins of the principal system.[67]
Sixthly, The rapidity with which, in certain experiments, the
annihilation of the cerebral action succeeds to the insufflation
of air into the veins, might almost persuade us that such
phenomenon is occasioned, as it is in wounds of the heart and
syncope;--but 1st. The most simple inspection is sufficient to
shew us that the heart continues to act after the apparent death
of the animal.--2dly. As the motions of the heart are prodigiously
accelerated by the contact of the foreign fluid, they push on
the frothy blood with an extreme velocity, and hence we have the
reason, why the brain in such case is so rapidly affected.
Seventhly, Were the cerebral action in this sort of death
interrupted for want of movement from the heart, it would happen as
it does in great hemorrhages of the aorta; that is to say, without
violent convulsion. But here, on the contrary, the convulsion
is extremely violent, immediately after the injection, and
consequently, announces the presence of an irritating substance on
the brain.
We shall conclude, that in the accidental mixture of air with the
blood of the venous system, it is the brain which dies the first,
and that the death of the heart is the consequence of the death
of the brain. I shall explain in another place, in what way this
phenomenon is occasioned.
FOOTNOTES:
[56] It is not true that a ligature on a nerve produces its effects
only on the part to which this nerve is distributed; the brain is
also affected; for, without this, how can be explained the pain
that is felt, and the excitement, which is often sufficiently
powerful to produce convulsions, and sometimes even death.
[57] The facts related here by Bichat are not conformable to those,
which, the philosophers and physiologists have observed who have
been more particularly engaged with this kind of experiments.
Besides the consequences which he has drawn from them are not
accurate, and he seems to be ignorant what course the galvanic
fluid in this case takes.
[58] If there is always a relation between the vital energy of the
brain and its alternate motions, it is because there is a constant
relation between these motions and the entrance of the blood into
the organ. Thus then, instead of considering this shock as the
exciting cause of the brain is it not more natural to see in it
only an effect purely accidental of the arrival of the arterial
blood, which every thing proves to be the real excitant?
[59] As we know absolutely nothing of the manner in which the
intellectual phenomena are produced in the brain, we cannot
say whether compression prevents their development by stopping
the motions with which the brain is habitually agitated, or by
preventing the entrance of the arterial blood, or finally in some
other way that we do not suspect.
[60] The organization of these animals differs too much from that
of man to enable us to draw conclusions from one to the other,
especially in what concerns the functions of the nervous system.
There is an experiment of M. Dumeril in which a salamander lived a
long time after the amputation of the head, till the formation of a
perfect cicatrix in the neck, which intercepted the passage of air
to the lungs.
[61] Why are not the cerebral functions disturbed, when water is
pushed slowly into the carotids? because there is then mixed with
the blood of the artery too small a quantity of water at a time to
enable this fluid to have a very evident action on the brain. But
if this introduction of water into the mass of blood continues,
whatever precaution may be taken, its effects soon show themselves.
We have often, in our experiments, introduced a great quantity of
water into the veins of an animal, and though much of it passed
off by pulmonary transpiration, the arterial blood soon became
very aqueous. Now, we have always observed, that in this case,
the animals were struck with a kind of stupidity, which evidently
indicated a want of action of the brain.
[62] It is not uncommon to see patients, who retain their
intellectual faculties perfectly, when the motions of the heart
are so feeble, that they certainly cannot produce, in the mass of
brain, any sensible jar.
[63] A very considerable quantity of air can be forced into the
veins of an animal, without causing its death, provided it be not
pushed in suddenly. In all these cases, it is understood, that the
quantity that can be thus introduced is in proportion to the size
of the animal. I have before me at this moment the details of an
experiment that I made on a horse at Alfort with M. Dupui, and in
which, before the animal died, I was able, in thirty seven minutes,
to inject quickly into the veins forty syringes full of air, and
three syringes full into the carotid artery. (The capacity of the
syringe was seventeen centilitres.) The animal died three minutes
after the last injection. At the examination of the body, we found
air in the azygos vein and in the thoracic duct, which contained
much lymph, as well as the lymphatic vessels of the internal
surface of the lungs. The heart was enormously distended with air
mixed with a small quantity of blood.
[64] This is not correct, and death takes place, on the contrary,
by the cessation of the motions of the heart. The right ventricle
is filled with air; and this air, dilated by heat, so distends it,
that it can no longer contract.
[65] The disorders which are produced in this case do not at all
resemble those which follow the entrance of air into the veins.
If we push towards the brain, by the carotid artery, a small
quantity of air, we see almost immediately signs of a strong
cerebral congestion, spasmodic stiffness of the muscles, loss of
sensibility, and of the action of the senses, and all the phenomena
of a real apoplexy. Respiration and the circulation go on some time
without any apparent alteration, but finally these two functions
become embarrassed and the animal sinks. Every thing leads to the
belief, that the alteration in the circulation of the brain depends
here on the presence of rarefied air in the ultimate arterial
ramifications.
When apoplexy is thus produced by the injection of air, if it
be still forced into the artery, it breaks open violently a
passage for itself, it tears the small vessels, and spreads in
the parenchyma of the brain, which it makes emphysematous and
crepitating under the finger. There finally returns a portion of
it by the veins, which goes to the right cavities of the heart and
which contributes to arrest the circulation.
[66] In the two examinations related by Morgagni, it appears that
after a sudden death, there was found in the vessels of the brain
an aeriform fluid, to the presence of which, for the want of
another material cause, was attributed the death of the individual;
but there is no proof that this fluid might not be developed there
after death. We shall now relate a more decided case of death
occasioned by the presence of air in the blood vessels; but here
there is no ground for doubt, because we know the circumstances of
the introduction.
A locksmith, twenty three years of age, had had for five years
a large tumour on the right shoulder and clavicle. His acute
sufferings induced him to enter the hospital to have it removed.
It was necessary in the operation to remove the middle portion
of the clavicle. Thus far the success was complete; but little
blood was lost, the pulse was good and the breathing easy, when
the patient suddenly cried out, _My blood is leaving my body!
I am dead!_ And at the same moment he became stiff, lost his
consciousness, and was covered with a cold sweat. A singular and
rather loud noise was heard in the interior of his chest. The
surgeon thought that he had opened the pleura by removing a portion
of the clavicle, and thus given access to the air and to the blood
to the right side of the thorax. The fingers of an assistant were
immediately thrust into the bottom of the wound, with the view
of stopping the supposed opening in the pleura, and the surgeon
endeavoured to introduce into the thorax the extremity of a sound
of gum elastic. When he thought that he had succeeded, he drew with
his mouth the air which he supposed to be effused in the pleura. He
wished then to proceed to the dressing; and, in order to do this,
he substituted, for the fingers of the pupil which were at the
bottom of the wound, a sponge covered with wax; but the moment the
sponge took the place of the fingers, the same noise that was at
first heard and which had ceased in an instant, was renewed with
more force than before.
The syncope and cold sweat still continued. Water thrown into his
face, made him give some signs of life; but he died a quarter of an
hour after the appearance of the accident I have just described,
and forty five minutes after the commencement of the operation.
The body was examined the next morning. They expected to find the
right pleura open, much blood and air effused into its cavity
and the lungs on that side collapsed. Nothing of the kind was
found. The pleura was whole and there was no effusion in it. The
lungs were as usual; but an opening of half an inch in extent was
discovered in the external jugular vein, at the place where this
vein opens into the subclavian. The cavities of the heart were
large but contained no blood. Bubbles of air were observed in the
vessels of the brain; the other vessels were not examined.
This fact was related to me the same day, by a student who was
present. It was impossible for me not to refer the death in this
instance to the entrance of air into the vessels. The opening in
the vein, the noise that was heard, the suddenness of the death,
the absence of blood in the cavities of the heart, the presence
of air in the vessels of the brain, all sufficiently indicated
it. I suspected that the entrance of air had been favoured by the
state of tension of the parietes of the vein, or by their morbid
alteration, which did not allow them to flatten by atmospheric
pressure. I thought that this phenomenon might be produced at will
on animals by placing them in the same physical circumstances. I
introduced then into the jugular vein of a dog, a sound of gum
elastic, and I directed it towards the heart. It was hardly there
before I heard the air enter the vein, and the animal fell down in
syncope, with the peculiar noise which manifests the presence of
air in the heart. I immediately closed the sound to prevent the
entrance of more air, and the animal gradually recovered, because
the quantity of air introduced had not been in sufficient quantity
to produce its death. I then opened the sound, and immediately the
air rushed in towards the heart, and its entrance was followed by
the same consequences; but, whether from not closing the sound
soon enough, or from the entrance of a greater quantity of air,
the animal died unexpectedly to me. In opening it, I found all the
signs of death from the sudden entrance of air. The right ventricle
was distended with air mixed with a little blood.
Sometimes, without any apparent alteration in the texture of the
veins, its parietes do not flatten under atmospheric pressure;
a simple puncture then is sufficient, as in bleeding, to admit
the air into the vessels. Lieutaud relates two cases in which it
appears that this took place, and several veterinary surgeons have
assured me that they have heard, after bleeding in the jugular
vein, a noise which indicates the entrance of air. Usually the
quantity introduced is too inconsiderable to produce any evident
effects. There has been communicated to me, however, a case
observed by Mr. Bouley, the younger a veterinary surgeon in Paris,
in which the entrance of air was followed by effects similar to
those which we have related.
Mery had long since observed, that, in opening the abdomen of
a dog, and puncturing the vena cava above the origin of the
emulgents, as the vein become emptied of blood, it filled with air,
which went to the right ventricle. Haller also observed that air
entered into the veins of frogs and other cold-blooded animals in
consequence of a wound of some large vessel. He has shown that it
was from this source that was derived that which Redi, Caldesi, and
Morgagni saw circulating in the vessels of these animals, since
it is not observed, when the necessary precautions are taken to
prevent its introduction.
Nysten has made a great number of experiments upon the injection
of elastic fluids into the veins, and the results which he has
obtained accord perfectly with those which we have observed. He is
not satisfied with injecting atmospheric air, he has introduced in
the same way a great number of other gases. He has remarked, that
among the gases not deleterious he can introduce, without causing
death, a much greater quantity if these gases are easily dissolved
in the blood.
We cannot follow him in the detail of these experiments; we shall
only relate a result relative to the colouring of the blood in
the lungs. He has observed, that by injecting air into the vein,
so slow as not to produce the death of the animal, the colouring
of the arterial blood is rendered imperfect. He is satisfied, he
says, that it is not owing to the embarrassment of the lungs. The
injection of oxygen does not alter this colouring. The injection
of azote completely prevents it; that of the oxide of carbon does
not produce any change in it. I give these results from his work; I
have not had occasion to verify them myself.
[67] When air is introduced into the vena portæ, there is not only
no ill effect at the moment of injection, but there usually follows
no apparent effect on the animal. It is not the same when air is
injected into the veins of the general system, with so much care
as not to produce instantaneous death by the dilatation of the
heart. The effects do not then appear till a long time after the
injection; but they are wholly different from the primary effects
which we have described.
These consecutive symptoms from the entrance of air into the veins
are, as Nysten has remarked, the result of an obstruction of the
lungs produced by the accumulation of air in the last divisions
of the pulmonary artery. The embarrassment in respiration often
appears at the end of half a day, it becomes greater and greater,
the bronchiæ are filled with a viscid fluid; and the animal usually
dies on the third or fourth day. On examination of the body, no
air is found in the heart or the vessels; but the lungs, instead
of being pink-coloured, are greyish, tinged with brown, and loaded
with frothy blood and mucus.
Boerhaave thought, that death which follows the injection of
air into the veins was always owing, as it is in this case, to
the presence of the air, which offers, in the small vessels, a
mechanical obstacle to the passage of the venous blood.
CHAPTER III.
OF THE INFLUENCE OF THE DEATH OF THE HEART OVER THAT OF THE LUNGS.
The lungs are the seat of two very different sorts of phenomena.
The first, which are entirely mechanical, are relative to the
rise and fall of the ribs and diaphragm, to the dilatation and
contraction of the air vessels, and to the entry and exit of the
air, which is the effect of these movements. The second, which are
purely chemical, may be referred to the different alterations,
which the air and blood experience.
These two sorts of phenomena have a mutual dependence on each
other. Without the mechanical, the chemical changes could not be
made; without the chemical changes, the blood would cease to become
an excitant to the brain, in consequence of which that organ would
no longer operate upon the diaphragm or intercostal muscles; the
muscles themselves would then become inactive, and the motions of
the thorax be annihilated. These phenomena, however, are put an end
to in a different manner by the death of the heart, accordingly as
it happens on one or the other side.
I. _In what manner are the actions of the lungs interrupted, when
the black-blooded heart ceases to act?_
The heart has certainly no influence over the mechanical functions
of the lungs, but it contributes essentially to produce the
chemical changes which are made there, by sending thither the
fluid which is destined to undergo a change. When its functions
then are interrupted as may happen from wounds or be occasioned by
ligature, the chemical changes which should be made in the blood,
are suddenly suppressed; though the air continue to enter into the
lungs, from the dilatation and contraction of the chest.
Meanwhile there arrives nothing at the red-blooded heart, or[68]
so little as to be insufficient for the production of the cerebral
movements. The functions of the brain are consequently suspended,
and of course the movements of the diaphragm and ribs.
II. _In what manner are the actions of the lungs interrupted, when
those of the red-blooded heart are suspended?_
Whenever from wound, ligature, or aneurism, the functions of the
red-blooded heart or aorta cease, the functions of the lungs are
terminated in the following order:
1st. There is no further impulse made upon the brain. 2dly, No
further movement of that organ.[69] 3dly, No further action
exercised upon the muscles. 4thly, No further contraction of the
intercostals or diaphragm. 5thly, The mechanical functions of the
lungs cease. 6thly, Their chemical functions cease.
In the former case, the chemical changes could not be made for want
of blood. Here they cannot be made for want of air. Such is the
difference in the death of the lungs, in consequence of that of the
heart, according as the latter is affected. But as the circulation
is very rapid, there cannot be but a very short interval between
the interruption of the chemical and the mechanical functions of
the lungs.
FOOTNOTES:
[68] After the obliteration of the ductus arteriosus, the left
ventricle receives no blood but what comes from the lungs; now, if
the motions of the thorax continue, it is red blood; at least so
long as the air is freely admitted into the bronchial tubes, and so
long as the composition of this fluid is not changed by the mixture
of foreign gases.
[69] These two modifications should, after what we have said, be
reduced to a single one, viz. want of excitement of the brain by
the arterial blood.
CHAPTER IV.
OF THE INFLUENCE OF THE DEATH OF THE HEART OVER THAT OF ALL THE
ORGANS.
I shall divide this chapter, as the preceding one, into two
sections. In the first I shall examine, how the death of the
red-blooded heart, in the second how the death of the black-blooded
heart, is the cause of the death of all the parts of the body.
I. _On the death of the red-blooded heart, and how that of the
organs is occasioned by it._
All the functions belong either to the animal, or to the organic
life. Hence the difference of their classes. Now the death
of those of the first class, in consequence of lesions of the
red-blooded auricle and ventricle, is caused in two ways, and
first, because the brain in such case is rendered inert from want
of impulse, and can neither have sensations, nor exercise an
influence over the locomotive and vocal organs.
Accordingly, all this order of functions is stopped, as when the
encephalic mass has experienced a violent concussion. It is in this
way that a wound of the heart, or the bursting of an aneurism,
annihilate all our relations with external objects.
So strict a connexion between the movement of the heart, and the
functions of the animal life, is not observable in those animals
in which the brain, in order to act, does not require the habitual
stroke of the blood. Tear away the heart of a reptile, or tie its
large vessels, and it will continue for a long time to move and
have sensations.
Besides, supposing even that the action of the brain were not to be
suspended from lesions of the red-blooded heart, the animal life
would not, on that account, be the less put an end to; because
to the exercise of the functions of this life, is attached as a
necessary cause, the excitement of its organs by the afflux of
blood into them: now this excitement, both here and every where
else, depends upon two causes.--1st, On the movement impressed,
and 2dly, On the nature of the blood. At present I shall only
examine the first mode of influence; the latter will come under our
consideration, when we speak of the lungs.
Habitual motion is necessary to all the parts of the body alike, is
a condition essential to the functions of the muscles, the glands,
the vessels, and the membranes, &c. But this movement, which is
partly derived from the heart, is very different from that which
is communicated by the blood to the brain.
The latter organ receives an impulse by which the whole of its mass
is visibly raised, an impulse, in the intermission of which the
whole of its mass subsides. On the contrary, the interior movement,
by which its particles are affected, is scarcely marked at all: and
this depends upon the smallness and the delicacy of the vessels by
which its substance is penetrated.
The contrary of this appearance is observed in the movement
occasioned in the other organs by the influx of the blood into
them: we see them neither rise nor subside; there is nothing
like a general impulse made upon them, because, as I have
said, such impulse is lost from the little resistance of the
surrounding parts. On the contrary, they are penetrated by vessels
of considerable magnitude, which create an intestine motion,
oscillations, and impulses adapted to the actions of the tubes,
lamellæ, or fibres, of which they are composed. This difference
of movement may be easily conceived, by comparing the manner in
which the brain on the one hand, and on the other the liver, the
spleen, the muscles, or the kidneys receive their blood; indeed it
is requisite that the brain should be distinguished from the other
organs, in the manner of receiving its impulses, because it is
enclosed in a case of bone, and consequently abstracted from the
thousand other causes of agitation, to which the other parts of the
body are exposed.
For we may remark, that all the other organs have about them a
number of agents, which are destined to supply the place of that
general impulse, which is wanting to them on the part of the heart.
In the breast, the intercostals and diaphragm are continually
rising and falling; the lungs and the heart are successively the
seat of a dilatation and contraction. In the abdomen, there is an
uninterrupted agitation produced, by the influence of respiration
upon its muscular parietes; an incessantly variable state of
the stomach, intestines and bladder. Lastly, from the various
contractions of the muscles, the limbs have a still more evident
cause of movement.
Nevertheless, it is probable that every one of the organs, as well
as the brain, has a general though obscure movement impressed upon
it, from the pulsation of the arteries; and hence, perhaps, we have
the reason, why the greater number of the viscera, receive the
impulse of the red blood upon their concave surfaces, as may be
seen in the kidneys, the liver, the spleen, and the intestines. By
such disposition, the impulse of the heart is less divided.[70]
From what has now been said, we may add another reason to that
which we have before given, for establishing in what way the
functions of the animal life are interrupted from cessation of
action in the red-blooded heart. We may now also begin to explain
the same phenomenon in the organic life. The reason of such
interruption in both the lives is the same. It is as follows:
1st. In the case of death affecting the red-blooded heart; the
intestine movement, which proceeds from the manner in which the
arteries are distributed within the substance of all the organs,
both of the one and the other life, is suspended; hence there
exists no farther cause of excitement for the organs: they must
consequently die.--2dly. The causes of the more extensive and
general movements of the organs are abstracted; for almost all
these causes depend upon the brain. We respire and move, only
while the brain is alive: but as the brain must be in a state of
collapsus, as soon as it ceases to receive the impulse of its
blood, its influence must be evidently annihilated.
Hence it follows, that the heart exercises over the different
organs two modes of influence; the one direct and immediate, the
other indirect, and made through the medium of the brain, so that
the death of the organs in consequence of the death of the heart,
is immediate or mediate.
We have sometimes examples of partial death, analogous to this sort
of general death. Thus, when the circulation is impeded in a limb,
and the red blood no longer distributed to its parts, such parts
become at first insensible and paralytic, then gangrenous. The
operation of aneurism furnishes us with too many instances of this
phenomenon, which by ligature, may be produced also in the living
animal. Undoubtedly the principal cause of death in these cases, is
the want of that stimulus which it is the business of the particles
of the red blood to create, in contradistinction to those of the
black blood, but the absence of the intestine movement in question,
is by no means a less real cause of such death.
As for the interruption of the nutritive process, it cannot be
admitted as a cause of the symptoms which succeed after the
obliteration of a large artery. The slow, the gradual, and
insensible way, in which this function is performed, does not
accord with the sudden and instantaneous production of those
symptoms, especially as they affect the animal life; for this is
annihilated in the limb at the very instant when the blood ceases
to flow into it, just in the same way as it is, when by the section
of its nerves, the influence of the brain is abstracted.[71]
Besides the preceding causes, which, when the heart is dead,
suspend in general the whole of the animal and organic functions;
there is another cause of death which especially affects the
greater number of the latter, such as the processes of nutrition,
exhalation, secretion, and therefore digestion, which is only
performed by means of the secreted fluid. This cause of death to
which I refer, consists in the necessary stop which is put to these
different functions, in consequence of their no longer receiving
the materials upon which they are exercised. Nevertheless, such
term arrives by degrees only, because they receive the materials
on which they act, from the capillary, and not from the general
circulation. Now the capillary circulation, is only subject to the
influence of the insensible contractile powers of the parts in
which it is performed; and is exercised independently of the heart,
as may be seen in the greater number of reptiles, where the heart
may be taken away, and the blood be notwithstanding observed to
oscillate for a long time afterwards in the minuter vessels.[72]
It is manifest, then, that whatever quantity of blood is left in
the capillary system at the period of the death of the heart, will
for some time afterwards be sufficient to keep up the functions
in question, and that such functions in consequence will only
gradually cease.
The following is a general view of the manner in which the
annihilation of all the functions succeeds to the interruption of
those of the heart.
The animal life is terminated--1st, Because the organs of which
it is composed, are no longer excited without, by the movement of
the neighbouring parts, nor within, by the blood.--2dly, Because
the brain, from want of excitement, can no longer be a cause of
excitement.
The organic life is terminated--1st, Because, as in the animal
life, there is a want of external and internal excitement for its
different viscera.--2dly, Because there is a want of the materials
on which its functions are particularly exercised.
There are a number of other considerations, however, besides those
which we have mentioned, which prove the reality of the excitement
of the organs, from the movement communicated to them by the blood,
as well as the reality of the cause, which we have asserted to be
that of their death, when such excitement ceases.
For, 1st.--The organs which are penetrated only by the serum of the
blood, such as the hair, the nails, the tendons, and cartilages,
enjoy a less degree of vitality, and a less energetic action, than
those in which the blood is made to circulate, either immediately
by the heart, or by the insensible contractile powers of the parts
themselves.
2dly.--When the white organs are inflamed, they receive an
augmentation of life, a superabundance of sensibility, which
frequently put them on a level in many respects with those organs,
which in their natural state are endowed with the highest degrees
of life and sensibility.
3dly.--Those organs which habitually receive the influx of the
red blood, when inflamed, exhibit, in every instance, a local
exaltation of the phenomena of life. In the two preceding
instances, it is true, indeed, that the change of vital powers,
precedes in point of time, the change which is made in the
circulation; the organic sensibility of the part, has been
augmented before the blood is carried thither in greater quantity;
but afterwards it is the afflux of such increased quantity
of blood, which keeps up the unnatural action which has been
established. A determined quantity of blood in the ordinary state
of the part, is necessary to the maintenance of that state; but
when the part receives a double or triple increase of energy, its
excitant also must be doubled or tripled; for in the exercise of
the vital powers, there are always three things to be remarked; the
power inherent in the organ; the excitant which is foreign to it;
and the excitement which is the product of the two.
4thly.--It is doubtless, for this reason, that the organs to which
the blood is habitually carried by the arteries, enjoy a degree
of life, proportionate to the quantity of fluid by which they are
injected. Such phenomenon may be observed in the glans penis, in
the corpora cavernosa, in the nipple, in the skin of the face, and
the actions of the brain, whenever the blood is directed with
impetuosity towards them.
5thly.--The whole of the circulatory system, is thrown into greater
action from the exaltation of the whole of the vital phenomena,
just in the same way as the particular circulation of any part
is augmented, when the particular phenomena of the life of that
part are increased. The use of spirituous liquors, and spices to
a certain quantity, is followed for a time by a general increase
of energy in the powers of the system. The access of inflammatory
fever will double and triple the intensity of life.
In these considerations I have only regarded the movement which is
communicated to the organs by the blood. In another place I shall
call the attention of the reader to that species of excitement,
which is produced by the nature of the blood, by the contact of
its component particles when in a state of oxydation or otherwise,
with the different parts of the body. The reflections which I have
offered, will be amply sufficient to convince us how much the
blood, independently of the materials which it conveys with it, by
its simple influx, is necessary to the activity of the organs, and
consequently how much the cessation of the functions of the heart,
must influence the death of the organs.
FOOTNOTES:
[70] It should not be lost sight of, that all this discussion
turns upon the application of a principle which is by no means
proved: viz. that the different organs, in order to exercise their
functions, require to be agitated by a partial or general motion.
We have already made it appear, that as it respects the brain,
this jarring of the whole mass, to which Bichat attributes so much
importance, appears to be a circumstance purely accidental from
the entrance of the arterial blood. The same may be said of the
oscillatory motion produced in the other organs by the pulsation of
the ultimate arterial ramifications.
[71] When the passage of the arterial blood to a muscle is stopped,
a more or less complete numbness soon takes place; and this
effect is too sudden to be attributed to the want of nutrition;
and as certainly it is not owing to the want of agitation by the
pulsations of the small arteries; for if, the artery is left
free, and a ligature is applied upon the vein, the pulsations are
increased rather than diminished and yet the numbness appears as
quick as before.
When the muscle has been a long time without receiving blood,
gangrene seizes upon it; and this can then be attributed, in
great measure, to the want of nutrition. The diminution of the
temperature, which necessarily takes place in an organ in which the
blood is not renewed, must also contribute to this disorganization.
[72] We know that the blood pushed into the arteries distends the
parietes of these vessels, and brings into action their elasticity;
now, after the heart has ceased to act, these parietes, by
contracting, can impart, for some instants, an oscillatory motion
to the fluid contained in their cavity.
CHAPTER V.
OF THE INFLUENCE OF THE DEATH OF THE HEART AS TO THE PRODUCTION OF
GENERAL DEATH.
Whenever the heart ceases to act, general death is produced in
the following manner:--1st. For want of excitement the cerebral
actions are annihilated, and consequently an end is immediately put
to all sensation, locomotion, and utterance. Besides, for want of
excitement on the part of the blood, the organs of these functions
would cease to act, even supposing that the brain were to remain
unaffected, and exert upon them its accustomed influence. Thus the
whole of the animal life is suddenly suspended, and at the instant
of the death of the heart, the individual is dead to what surrounds
him.
The interruption of the organic life, which has commenced by the
death of the heart, is produced at the same time by that of the
lungs. The brain being dead, the mechanical functions of the lungs
must cease: the chemical functions of the lungs must cease also,
for want of the materials on which they are exerted: the latter are
directly interrupted, the former through the medium of the brain.
After this the progress of death is gradual. The secretions, the
exhalations, the nutritive actions are put an end to. The latter
are first arrested in those organs which receive the more immediate
impulse of the blood, because in these, such impulse is necessary
to the performance of the functions. The paler organs are less
dependent on the influence of the heart, and consequently must be
less affected by the cessation of its action.[73]
In the successive termination of the latter phenomena of the
internal life, the vital powers continue to subsist for some time
after the loss of the functions: thus, the organic sensibility, and
the sensible and insensible contractilities survive the phenomena
of digestion, secretion, and nutrition.[74]
The vital powers continue to subsist in the internal life, even
when the corresponding powers of the animal life, have suddenly
become extinct: the reason is plain: the power of perceiving and
moving organically does not suppose the existence of a common
centre; for the animal perceptions and motions, the action of the
brain is requisite.
The phenomena of death are concatenated in the above order in all
aneurismal ruptures, in all wounds of the heart or larger vessels,
in all cases of polypi formed in the cardiac cavities,[75] of
ligature artificially applied, of compression exercised on the
parietes of the heart by humours, abscesses, &c. &c.
It is in this manner also that we die from sudden affections of the
mind. The news of a very joyful, or a very melancholy event, the
sight of a fearful object, of a detested enemy, of a successful
rival, are all of them causes capable of producing death. Now in
all these instances, it is the heart, which is the first to die,
the heart, whose death successively produces that of all the other
organs, the heart, on which the passion is exerted.
And hence we are led to some considerations on syncope, an
affection exemplifying in a less degree the same phenomena, which
in a greater one, is offered us in cases of sudden death.
The causes of syncope are referred by Cullen to two general heads:
Of these there is one set which according to him affect the brain,
another set which affect the heart. Among the first, he places the
more violent impulses on the mind, and various evacuations, but
it is easy to prove, that the brain is only secondarily affected
in syncope produced by passion, and that it is the heart, whose
functions in all these cases are the first to be interrupted. The
following considerations, if I am not mistaken, will leave but
little doubt on this head.
1st.--I have proved, in speaking of the passions, that they never
affect the brain in the first place; that the action of this
organ, in consequence of their development, is only secondary, and
that every thing relating to our moral affections has its seat
exclusively in the organic life.
2dly.--The phenomena of syncope when produced by lively emotion,
are similar in every respect to those of syncope, the effect
of polypi or dropsy of the pericardium, but in the latter,
the affection of the heart is the primary one, and should in
consequence be the same in the former sort of syncope.
3dly.--At the moment when syncope takes place, we feel the attack
at the heart, and not in the brain.
4thly.--In consequence of lively passions, which may have
occasioned syncope, we find that the heart and not the brain
becomes diseased, nothing is more common than organic affections
of the former from sorrow, &c. The different sorts of madness,
which are produced by the same cause, for the most part have
their principal seat in some of the viscera of the epigastrium,
and in such case, the irregularity of the cerebral action is the
sympathetic effect of the profound affection of the internal
organ.[76]
5thly.--I shall prove hereafter, that the cerebral system does not
exert any direct influence over that of the circulation; that there
is no reciprocity between the two, and that the changes of the
first are not followed by similar changes in the second, however
much the changes of the second may modify the first. Destroy all
nervous communication between the brain and the heart, and the
circulation will go on as usual; but if the vascular communications
be intercepted, the cerebral action vanishes at once.
6thly.--Palpitations and other irregular movements of the heart are
often the effect of the same causes, which in some individuals are
the occasion of syncope. In such cases, it is easy to discover the
seat of the affection, and such smaller effects of the passions on
the heart, are very well calculated to throw light upon the nature
of the greater.[77]
From these many considerations, we may conclude that the primitive
seat of the attack in syncope, is the heart, which does not cease
to act, because the action of the brain has been interrupted, but
because it is the nature of some of the passions in such way to
affect it, the brain at the same time, suffering a temporary death,
because it no longer receives the fluid, which is necessary to its
excitement. The nature of syncope is well enough illustrated, by
the vulgar expression of being sick at heart.
It is of no importance to our present purpose, whether syncope
depend on polypi, on aneurism, or be the result of some violent
emotion. The successive affection of the organs is always the same.
They die for the moment in the same way, as they really perish when
the heart is wounded, or a ligature put upon the aorta. In the same
manner also are those sorts of syncope produced, which succeed
after any great evacuation of blood, pus or water. The heart is
affected from sympathy, the brain for want of its excitant.[78]
Those cases of syncope which are occasioned by peculiar odours,
by antipathies, &c. appear also to be attended with the same
progression of symptoms, though their character be much less easily
understood. There is a great difference between syncope, asphyxia,
and apoplexy, in the first it is by the heart, in the second by the
lungs, in the third by the brain that begins the general death of
the body.
Death, as it happens in consequence of disease, in general
exemplifies a concatenation of these different symptoms. The
circulation, respiration, or cerebral action cease, the other
functions are afterwards interrupted of necessity, but in these
sorts of death, it rarely happens that the heart is the first to
die. This however is sometimes the case. After long continued
suffering, great suppuration, and sometimes, in dropsy, certain
fevers, and gangrenes, one fit of syncope comes on after another,
at last a longer one succeeds, and the patient dies, but whatever
be the part affected, whatever the diseased viscus or organ,
whenever the phenomena of death commence by the heart, they succeed
each other as we have described them to do in sudden death, from
lesion of that organ. In other cases, the heart is the last to act,
is the ultimum moriens.
In general, in morbid affections, we much more commonly observe the
ingress of death to be made by the lungs, than either by the heart,
or the brain.
Whenever disease is terminated by syncope, the lungs are found to
be almost empty, and if not affected by any organic disease, are
collapsed, occupy a part only of the cavity of the thorax, and are
of their natural colour.
The reason of this anatomical fact is simple. The circulation
which has been suddenly interrupted, has not had time to fill the
vessels of the lungs, as happens when death begins, by affecting
the lungs or the brain. The truth of this fact I can vouch for,
having frequently ascertained it by dissection, and in general, as
often as death commences by the heart, or the larger vessels, such
vacuity of the lungs may be considered as universal.
I have remarked it in the bodies of persons who have died from
great hemorrhage from wounds or aneurismal rupture and violent
passion, as well as in those who have suffered by the guillotine.
The same phenomenon may be seen, by inspecting the lungs of any
animal, which is killed in our butcheries.
In killing the animal slowly by the lungs, that organ might be
filled with blood. Its taste would then be different from that
which it naturally possesses, and resemble that of the spleen. Our
cooks know well how to take advantage of that state of infiltration
in which the latter viscus is generally found.
FOOTNOTES:
[73] Life is so obscure in the tendons, ligaments, &c. that it is
impossible to fix the moment when it ceases in these parts. How
then has Bichat been able to compare the quickness of their death
with that of the other organs? Upon what data has he been able to
determine that it takes place more slowly?
[74] The secretion of mucus, the growth of the nails, the beard and
the hair often continue on the dead body long after the last traces
of irritability have disappeared in the muscles of locomotion, in
the fleshy coats of the intestines, &c.
[75] Since more care has been taken in examining the lesions of
different organs in post mortem examinations, there is no longer
found those fatty polypi, which were formerly considered as
causes of death. It is probable that those yellowish concretions
of albuminous matter which are found between the pillars of the
auricle, and which seem to be fixed there, were mistaken for
polypi. There is sometimes found in individuals formerly affected
with the venereal disease, vegetations near the valves; but these
productions are commonly too trifling to oppose the expulsion of
the blood contained in the cavity.
[76] The singular idea of placing the seat of madness in the
viscera of the abdomen, arose at a period when a certain number
of mystical ideas formed the basis of all physiology. The four
sorts of humours performed in the human body (_microcosm_)
a part as important as the four elements did in the whole
universe (_macrocosm_). The bile, the blood, the pituitary and
atrabiliary fluids determined, by their predominance the different
temperaments, and produced the different diseases. The atrabiliary
humour was, as is well known, thought to be the cause of melancholy
and mania; now this humour was said to be secreted by the
supra-renal capsules, and the position of these organs no doubt
gave the name of hypochondria, which is given to a certain degree
of mental alienation.
After a great number of ages, the mysterious properties of numbers
are almost entirely out of favour. We still speak of the four
temperaments, but attach no importance to the four ages of man or
to the four parts of the day. We recognize in the human body more
than four kinds of fluids, but among them all we do not find the
atrabiliary fluid. The cause of madness then cannot be attributed
to this humour, and yet we dare not drive this disease from the
seat it has so long held. In order to find reasons for keeping
it there, they seek in the viscera for disorders which are not
often found there even in the most striking cases, and which most
often still exist without the least alteration in the intellectual
functions.
[77] We should be often exposed to commit great mistakes, if we
always judged by this rule. The sensation is a very uncertain
means of determining the organ that is primarily affected; this
can be proved by numerous examples, we shall cite one only which
relates to the brain. Nausea and vomiting are often, as is well
known, among the first symptoms of cerebral affections; should we
from this believe that the seat of the disease is in the stomach?
Undoubtedly not: now, in syncope produced by a strong affection of
the mind, there is no reason to suppose that the heart is affected
before the brain, since the intellectual phenomena have necessarily
preceded the sensation of joy or of sorrow which has produced the
syncope. But to say that the brain was primarily affected, is not
saying that its action ceased before that of the heart; and every
thing, on the contrary, leads to the belief that the loss of the
senses is a consequence of the suspension of the circulation.
[78] The syncope is produced in this case, from the sudden change
in the circulation of the brain. But this change varies according
to the seat of the effusion. If it be in the peritoneal cavity,
the pressure that it makes interrupts the circulation in all the
organs contained in the abdomen; the descending aorta is found
compressed, and the blood, forced back towards the superior parts,
accumulates in the sinuses and vessels of the brain. If the fluid
be evacuated by puncture, the equilibrium is re-established in the
different parts of the vascular system, the blood enters vessels
which were before closed to it, it abandons in part those of the
brain, and it is this sudden change in the circulation of the organ
which produces syncope. If, on the contrary, the effusion be formed
between the two layers of the arachnoides, and we can, as in spina
bifida, evacuate the fluid by puncture, the vessels of the brain
are immediately relieved of the pressure to which they had been
subjected, and the blood, which before was forced back, towards the
inferior parts, is driven forcibly into them; the change is, as
must be perceived, the reverse of the preceding; but the result is
the same, and syncope is produced in this case as in the other.
CHAPTER VI.
OF THE INFLUENCE OF THE DEATH OF THE LUNGS OVER THAT OF THE HEART.
We have already said, that the functions of the lungs are of two
kinds, mechanical and chemical. Now the activity of this organ
ceases sometimes by the former, and sometimes by the latter of
these functions.
Any wound, which exposes the lungs on both sides, for a
considerable extent, occasions their sudden collapse; any division
of the spinal marrow, which suddenly paralyses the intercostals,
and the diaphragm; any very strong compression exerted at the same
time upon the whole of the thorax, and the parietes of the abdomen,
any sudden injection of a large quantity of fluid into this cavity,
are all of them causes which begin the death of the lungs, by
putting an end to their mechanical functions. Those which influence
in the first place their chemical functions, are the different
sorts of asphyxia, strangulation, submersion, and a vacuum, in
whatever manner produced.
I. _In what manner is the death of the heart occasioned by the
interruption of the mechanical functions of the lungs?_
The interruption of the functions of the heart, can only succeed
in two ways to that of the mechanical functions of the lungs: 1st.
Directly, because a mechanical impediment is put to the circulation
of the blood, by a state of collapse in the lungs. 2dly.
Indirectly, because in such state the lungs no longer receive the
materials, upon which their chemical functions are exerted, and
therefore cannot transmit them to the heart.
Physiologists have all of them admitted the first mode of
interruption, in the Pulmonary circulation. Reflected on
themselves, the vessels of the lungs have not appeared to them, to
be capable of transmitting the blood, on account of the numerous
angles which they make. This idea they have borrowed from the
phenomena of hydraulics, and it is their reason for the death which
ensues, in consequence of a too long continued expiration.
Notwithstanding all which, it has been proved by Goodwyn, that
in such case there remains a sufficient quantity of air in the
air vessels, for dilating them enough to allow of the mechanical
passage of the blood; he proves in consequence, that an unnatural
permanence of the state, in which the lungs are placed from the
act of expiration, does not affect the blood in the way, which is
commonly believed. This is one step towards the truth, but we shall
approach it much more nearly, and even attain it, should we be able
to prove, not only that there remains a sufficiency of air in the
lungs to permit the transmission of the blood, but that the very
folds produced in the vessels by a state of collapse in the organ
are not a real impediment to its course. The following observations
and experiments will assuredly determine this fact.
1st.--I have already proved, that a state of fulness or emptiness
in the stomach, and in all the hollow organs in general, produces
no apparent change in the state of their circulation; and that
the blood in consequence, will traverse the vessels, when bent or
doubled upon themselves, as easily, as when they are distended in
every direction. For what reason should a different effect be
produced in the lungs, by the same disposition of the parts?
2dly.--There are different vessels in the œconomy which we may
alternately bend or extend at pleasure: such are those of the
mesentery, when exposed by an incision into the abdomen of the
animal. Now in this experiment, which has been already made to
prove the influence of the tortuous direction of the arteries
upon the mechanism of their pulsation, if one of the mesenteries
be opened, and then either bent or extended, in either case the
blood will be thrown out with the same degree of violence, and in
equal times will be emitted in equal quantities. I have always
obtained the same result in this experiment which I have many times
repeated. From analogy we might expect the same from the vessels of
the lungs;[79] and from the following experiment it may be proved.
3dly.--Take a dog, cut the trachea, and adapt the tube of an
injecting syringe to it, then make a vacuum in the lungs, and cut
the carotid artery. It is evident, that according to the common
belief, the circulation should be immediately suspended, in this
experiment, since the pulmonary vessels from their ordinary state
of distension, must have passed to the greatest possible degree
of collapse, in consequence of the total abstraction of air;
notwithstanding which the blood will be violently thrown out from
the divided arteries for a certain time, and must consequently
traverse the lungs: it will afterwards cease by degrees, but this,
from causes which I shall explain hereafter.
4thly.--The same effect may be produced by opening, on both sides,
the breast of a living animal, because the warm and rarified air of
the lungs, will be more than balanced by the pressure of the colder
air without;[80] now, neither in this case does the circulation
experience any sudden change. For the sake of greater exactness,
the little air remaining in the cells of the organ may be voided
by a syringe.
Along with these observations let us place the facility with which
the pulmonary circulation continues to be made, when collections of
water, pus, or blood, are lying within the pleura, or pericardium.
In these cases the air vessels are often prodigiously contracted,
and consequently the vessels of their parietes doubled and
bent.[81] If this state be taken into consideration, we shall have
sufficient data for concluding that the tortuous disposition of the
vessels, can never be an obstacle to the passage of the blood; and
therefore, that the interruption of the mechanical functions of the
lungs, can never directly put a stop to the action of the heart,
though it may do so indirectly, in impeding the exercise of the
chemical functions of the lungs.
If then we can determine why the heart remains inactive, when the
latter phenomena are annihilated, we shall have resolved a double
question.
Many authors have asserted that the death, which ensues after a too
long continued inspiration, is owing to the mechanical distension
of the pulmonary vessels by the rarified air, a distension impeding
the circulation. But this reason also is as false a one, as that
which we have already disproved. Inflate the lungs as powerfully as
may be, then tie the trachea and open the carotids, and the blood
will flow as impetuously as when the respiration was perfectly
free.[82]
II. _Why does the heart cease to act, when the chemical functions
of the lungs are interrupted?_
According to Goodwyn, the reason why the contractions of the heart
are stopped, when the chemical functions of the lungs have ceased
to be performed, consists in the want of that excitement which the
red blood only can produce upon the red-blooded ventricle. This
ventricle, says he, has not a sufficient stimulus in the black
blood, and death is occasioned because it no longer is capable of
transmitting any thing to the different organs. In this case death
must happen, as it would from ligature of the aorta--precisely in
the same way as when its source is exclusively in the heart. The
other parts die only for want of blood, just as when in a machine,
the principal spring being taken away, the others cease to act,
because they are not put into action.
On the contrary, I am persuaded that there is a general affection
of all the parts, whenever the chemical functions of the lungs
are suspended; I am persuaded that the black blood continues to
be pushed on for some time by the aorta, and that its influx into
the organs is the occasion of their death; that the organs die in
fact, not because they do not receive blood, but because they do
not receive red blood; in a word, that they are penetrated by the
material cause of their death; so much so, that we may asphyxiate
any isolated part at will, by injecting it with venous blood while
all the others shall continue to receive the red blood of the
heart. At present I shall inquire into the phenomena of the contact
of the black blood with the parietes of the ventricle, and refer
the reader to the following chapters, for its effects upon the
other parts.
The movements of the heart may be stopped and made to cease
altogether from the influence of the venous blood in two
ways.--1st. As Goodwyn has said, because the left ventricle is
not excited by it upon its internal surface.--2dly. Because such
fluid, when carried into the substance of the heart by the coronary
vessels, must act upon the muscular fibre of the heart in the
same way as it does upon the other muscles. Now, for my part, I
am assured that the black as well as the red blood, will excite
into contraction the internal surface of the aortic ventricle. The
following observations and experiments will confirm my assertion.
1st. If asphyxia were to be followed by the consequences which
Goodwyn has supposed, it should influence the heart in the first
place; the annihilation of the functions of the brain, as in
syncope, should be only secondary; nevertheless, asphyxiate an
animal, by stopping up the trachea, by placing him in a vacuum, by
opening the chest, or plunging him into carbonic acid gas, and it
will in every instance be observed, that his animal life is the
first to be interrupted, and that the creature externally is dead;
but that within the heart continues for some time afterwards to
act, and the pulse to be felt.
In this way the symptoms of asphyxia are not the symptoms of
syncope. In the latter the cardiac and cerebral actions are
suspended at the same instant, in the former the heart survives,
as in cases of strong concussion of the brain for many seconds. It
follows, that in asphyxia, the different organs do not cease to
act, because the heart has ceased to supply them with blood, but
because it no longer supplies them with that sort of blood by which
they can be stimulated.
2dly. If the trachea of an animal be stopped, and an artery
opened, the colour of the blood which it emits, will gradually be
changed, and at last become as black as that of venous blood. Now,
notwithstanding this phenomenon, which is as apparent as it can be,
the fluid for some time afterwards is thrown out full as strongly
as it would be, were it red. I have seen a quantity of black blood
discharged in this way, more than sufficient to kill the creature
from hæmorrhage; were it not already dead, in consequence of its
asphyxiated state.
3dly. In the last-mentioned experiment, it may, indeed, be alleged,
that some remains of air in the air cells, might, as long as the
black blood continued to flow, have communicated to it a principle
of excitement; but to put it out of all doubt, that the venous
blood does really pass into the aortic ventricle, unaltered in its
passage from the corresponding cavity, the air may be entirely
pumped out of the lungs with a syringe, by exposing the trachea, in
the first place, and then adapting the instrument to the transverse
section of the tube; after this, let the carotid be opened; now
as soon as the red blood contained in this artery is exhausted,
the black blood will succeed to it, and that, without undergoing a
variety of gradations in colour; in this case also for a time, the
jet will be very powerful, and only be gradually weakened; but if
the black blood were not an excitant to the heart, its interruption
should be immediate.
4thly. The following is another proof of the same nature. Expose
the breast on one side by sawing exactly through the ribs before
and behind: when this is done, the lungs on that side will
collapse. Proceed to open one of the pulmonary veins; fill a
syringe warmed to the temperature of the human body with venous
blood, then push it into the red-blooded ventricle. Now, according
to the common opinion upon the subject of asphyxia, such fluid
should at least diminish in a sensible way, the movement of that
cavity, notwithstanding which, in four successive experiments, I
could not observe any such diminution. On the contrary, in one
of them, on pushing the piston, the strokes of the heart were
augmented in number.
5thly. If the black blood be not an excitant to the heart, it can
only want such power, because it contains more carbon and hydrogen,
than the red blood;[83] but if the heart of an animal, which has
been killed expressly for the experiment, by lesion of the brain or
of the lungs, has ceased to beat, it may, notwithstanding, be made
to contract as long as it preserves its irritability, by throwing
into the aortic ventricle either hydrogen gas, or carbonic acid
gas. It follows, that neither hydrogen gas nor carbon can act as
sedatives to the heart.
The experiments which I made and published last year, on the
emphysemata, produced in different animals with these gases, have
established the same truth with respect to the muscles, since they
do not cease to move in consequence of such experiments, and after
death, preserve their irritability as they usually do.
Lastly. I have often succeeded in re-establishing the contractions
of the heart, which have been annihilated in different sorts of
violent death, by the injection of black blood into the red-blooded
cavities, with a syringe adapted to one of the pulmonary veins.
Thus it is proved, that the red-blooded heart does actually push
the black blood into all parts of the body; and in this way is the
colour given to the different surfaces, of which, in one of the
following chapters, I shall offer a sketch.
Neither does the simple presence of the black blood act in a more
sedative way upon the internal surfaces of the arteries.[84] If,
in fact, while the tube adapted to the trachea is shut, the blood
be made to flow from an artery of the foot, it will be thrown out
for some time, with the same force which it would have been, were
the pipe to be open. The action, then, which it exercises in its
passage from the heart, upon the parietes of the arteries, does not
diminish the energy of these parietes. When this energy decreases,
it is at least in part from a different cause.
From the above experiments we may conclude, that the black blood
arriving in mass at the red-blooded ventricle, and correspondent
arterial system is able, from its sole contact with them, to
occasion the action of these cavities; we may be equally certain,
that were not the functions of these parts suppressed from other
causes, the circulation would continue to be made in a very
sensible manner, at least, if not with force.
Of what nature, then, are the causes which interrupt the
circulation in the heart and arteries when they are supplied with
venous blood? for when this has been flowing for some time, the jet
of it is gradually weakened, and ceases at last entirely; yet if
the cock of the pipe be opened, it will be restored with vigour.
I am persuaded that the black blood acts upon the heart as it
does on all the other parts, as we shall see that it affects the
brain--that it affects the voluntary muscles, the membranes, and
the system in general; the tissue of which it penetrates and
operates within it as a debilitant upon each individual fibre. I am
fully of opinion, that the circulation would be almost as quickly
interrupted as in the preceding cases, were it even possible to
supply the coronary arteries of the heart with red blood, while the
black blood is transmitted to the various parts of the body by the
aortic auricle and ventricle.
The black blood operates by its contact with the fleshy fibres, at
the extremity of the arterial system and not by its contact with
the internal surface of the heart. Thus it is only by little and
little, and when each fibre has been as it were injected, that
the powers of such fibres diminish and cease. On the contrary
supposition, their cessation and diminution should be almost sudden.
It may be demanded in what manner the black blood acts at the
extremities of the arteries, upon the fibres of the different
organs. Is it upon the fibres themselves, or upon the nerves
which are distributed to them? I am rather inclined to suppose
the latter to be the fact, and to consider asphyxia as an effect
produced in general by the black blood upon the nerves, which
every where accompany the arteries of a certain diameter: for as
we shall presently see, the debility which in such case the heart
experiences, is only a particular symptom of a disease in which the
organs in general are the seat of a like debility.
It might be demanded also in what way, that is to say, by what
manner of influence, the black blood acts upon the nerves or
fibres. Is it from the principles which it actually contains, or
from the absence of those which are proper to the red blood? Is
oxygen the principle of irritability--are hydrogen and carbon the
reverse?
These questions have been sufficiently disputed.--Let us stop when
we arrive at the limits of rigorous observation. Now, I think, that
we shall establish an assertion the most strictly conformable with
such principle, in saying generally and without determining the
manner, that the heart ceases to act, when the chemical functions
of the lungs are interrupted, because the black blood with which
its fleshy fibres are penetrated, is not of a nature to keep up
their action.
From this manner of regarding the phenomena of asphyxia with
relation to the heart, it is evident that both the ventricles
should be equally affected by it, because their parietes must be
equally injected with venous blood. Nevertheless, it is constantly
observable, that the movement of the red-blooded heart is the
first to stop; that the black-blooded heart in every case the
ultimum moriens; but this phenomenon does not suppose a more
real, a more decided debility in the one, than in the other
heart; for as Haller observes, the fact is common to every kind
of death in the red-blooded animal, and not the case particularly
in asphyxia.--Besides, were the red-blooded heart the first to
be absolutely affected, as the theory of Goodwyn supposes, the
following would be the appearances on opening the asphyxiated
subject.--1st. A distension of the corresponding auricle and
ventricle, by the black blood which they would not be able to expel
into the aorta.--2dly. An equal fulness of the pulmonary veins and
lungs.--3dly. A consequent fulness and swelling of the pulmonary
artery and the black-blooded cavities. In a word, the congestion of
the blood should be the greatest in that of its reservoirs, whose
action is the first to cease.
But this is contrary to observation--for 1st. In the asphyxiated
subject, the red-blooded cavities and pulmonary veins, contain but
a very small quantity of blood in proportion to that which distends
the opposite heart. 2dly. The place where the blood has stopped,
is found to be principally in the lungs, in the lungs must we
begin to follow its accumulation into the venous system. 3dly. The
arteries are as full of blood as their correspondent ventricles,
and consequently it cannot be in the ventricle more than elsewhere,
that death has been begun.
But what is the reason why the black-blooded heart is the last to
beat? because, says Haller, it is the longest excited; because it
contains a greater quantity of blood; because the blood is sent
into it from the largest veins of the system, and regurgitates from
the lungs. The famous experiment is well known by which in emptying
the black-blooded cavities, and tying the aorta so as to retain
the blood within the red-blooded cavities, the contractions of the
latter are prolonged so much beyond the contractions of the former.
But in this experiment it is manifestly the black blood which
accumulates in the aortic auricle and ventricle, because the breast
must be preliminarily opened, and therefore the lungs collapse.
Should a more direct proof be required, immediately before the
experiment, let the trachea be closed with a syringe, and the air
of the lungs be voided; the experiment will just as well succeed;
besides, the operator to be sure of the colour of the blood in the
aortic cavities, has nothing more to do than to open them, as soon
as he has finished his experiment.
We shall conclude that the black blood is almost as powerful a
stimulus as the red blood to the inner surface of those cavities,
which usually contain the latter only: the reason why they are
the first to be arrested in their action, is, because they do not
receive so large a quantity of blood as the others.
Notwithstanding what I have said, I do not entirely reject the
idea of the red-blooded ventricle being not excitable by the black
blood. It may indeed be less excitable by this sort of blood, than
by the other; but I believe that the preceding considerations will
reduce this difference of excitement to a mere trifle.
The following, however, is an experiment where such difference
would appear to be very manifest. If a stop cock be adapted to the
trachea, and an artery opened, the blood will blacken, and continue
for some time to be thrown out with its ordinary force, but at
last the jet will gradually grow weaker. If, after this, the air
be admitted, the blood will almost immediately become red and its
jet be visibly augmented. In this case the sudden augmentation
appears at first to depend upon the simple contact of the red fluid
with the sides of the aortic ventricle, since it has not had the
time to penetrate the tissue of the heart; but let things be a
little attentively examined, and it will soon be seen that this
impetuosity of impulse, depends on the movements of inspiration and
expiration, to which the animal is obliged, on the admission of
air into the lungs. The heart excited at its exterior, and perhaps
a little compressed by these movements, is the occasion of such
phenomenon, and expels the blood with a force which is far beyond
that which results from its habitual contractions.
What I have here advanced is proved, by the manifest diminution of
the jet, as soon as once the lungs have taken on their accustomed
degree of action. Besides, the influence of a series of full
expirations may be manifested without dividing the trachea. Open
the carotid and precipitate the respiration of the animal by
tormenting it (for pain will constantly have this effect) and the
jet of blood will be visibly increased. The same augmentation may
be artificially produced, by suddenly compressing the parietes
of the thorax. These experiments succeed best on animals already
weakened by the loss of a certain quantity of blood.
In the ordinary state of health however, a series of strong
expirations will not be found to quicken the pulse. Of this I
cannot assign the reason.
From what we have now said, it follows, that the experiment, in
which, on the opening of the cock of the syringe, the blood is
thrown out with augmented force, is not so conclusive as might at
first be imagined. I confess that it embarrassed me much for many
days, I hold then my former conclusions to be good.
In the red and cold-blooded animals, the action of the lungs has
not so immediate a connexion with that of the heart, as it has in
the red and warm blooded animals.
I tied the lungs of two frogs at their basis, having previously
exposed them, by incisions made laterally into the breast, the
circulation however continued as usual for a considerable time.
After this experiment, I have seen on opening the breast, the
movements of the heart precipitated, a circumstance depending no
doubt upon its contact with the air.
I shall finish this chapter by the examination of an important
question, and inquire into the reason, why when the chemical
functions of the lungs are stopped, the pulmonary arteries, the
black-blooded cavities of the heart, and in a word all the venous
system, are found so much more full of blood, than the aortic
system. In such case the circulation appears at first to be
interrupted in the lungs, and then in the other parts, according to
their proximity to the lungs.
This phenomenon must have been observed by all who have opened the
asphyxiated subject. It has been explained by Haller and others,
from the tortuosity of the vessels; but this opinion I have
sufficiently refuted.[85]
But before I proceed to assign a more real cause, I shall observe,
that the lungs, (when the blood is first arrested, because it
finds in them the first obstacle to its progress,) are found in a
singularly various state, according to the kind of death of which
the individual has died. In sudden, in instantaneous death, neither
the lungs, nor the black-blooded heart are very much distended.
I have observed this fact, 1st. In the bodies of two persons who
had hanged themselves and were brought into my amphitheatre. 2dly.
On two subjects who had fallen into the fire, and were instantly
suffocated. 3dly. On dogs which I have suddenly drowned. 4thly.
Upon guinea-pigs, which I have killed in a vacuum, or in different
gases, or otherwise.
On the contrary, arrest the phenomena of respiration in a gradual
manner; drown the animal by plunging him in water, and taking him
out alternately, asphyxiate him by placing him in a vessel of gas
imperfectly closed, continue as long as possible such state of pain
and anguish, and the lungs will be found extremely full of blood.
Between the extreme fulness, and the almost complete emptiness of
the pulmonary vessels, there is a variety of degrees; now by the
manner in which we kill the animal, we can determine any one of
these degrees at will: It is in this way that we must explain that
state of fulness in the lungs of such subjects, as are usually
brought into our amphitheatres: in the greater number of cases, the
attacks of death are slow and gradual.
But whatever be the state of the lungs in the asphyxiated subject,
the venous system is full of black blood, especially about the
heart. In this respect, there is always a very wide difference
between the veins and the arteries, and accordingly the blood must
find in the lungs the principal obstacle to its circulation: such
obstacle, as we have said, does not proceed from the tortuosity,
and state of collapse in the pulmonary vessels; its causes are
relative, first to the blood, secondly, to the lungs, thirdly to
the heart.
The principal cause depending on the blood, consists in the great
quantity of this fluid, which passes from the arteries into the
veins. In fact we shall soon see, that the black blood when it
circulates in the arteries, is not capable of furnishing the
materials of secretion, exhalation, or nutrition, or if it be so,
that it is not a stimulus to the organs which are the agents of
these functions.[86]
It follows as a necessary consequence, that the portion of fluid
which is usually taken up from the arterial system by these
different functions, flows on into the venous system, together
with the portion which should naturally pass thither; hence
there must be contained a greater quantity than usual in the
veins; and therefore a greater difficulty be experienced in its
passage through the lungs. Practitioners in opening the bodies of
asphyxiated persons, have always remarked the abundance of blood
which is met with there. The fact has been particularly remarked by
Portal, and I have always found it in my experiments.
The causes of obstacle to the passage of the blood proceeding from
the lungs, are first the non-excitement of this organ by arterial
blood. In asphyxia, the bronchial arteries are penetrated by the
black blood as well as the rest. Hence its obscure and dusky colour
in this case. This colour and its successive shades, may be easily
remarked in the collapsed lung, when the chest is opened; but in
asphyxia, such blackness is principally owing to the colour of the
blood, contained in the pulmonary veins.
The black blood when circulating in the bronchial vessels, produces
upon the lungs the same effect which it does in the heart, by
penetrating the coronary arteries; it weakens the different
parts--impedes their action, and the capillary secretions which
should be made there, from the tonic powers of the organ.
The second cause of obstacle to the circulation, when the chemical
functions of the lungs are interrupted, is the non-excitement of
the organ by vital air. The first effect of such air upon the
mucous surfaces of the air-cells, is to stimulate them, and so to
keep them up in a sort of perpetual erethism.[87] In the same way
are the powers of the stomach brought into action by the presence
of aliment there, and those of every reservoir of the body, by the
influx of their accustomed fluids. Again, such excitement of the
mucous surfaces by foreign substances keeps up their tone. The
privation of such excitement, therefore, must put a stop to their
capillary secretions, which depend upon their tonic powers.
The different aeriform fluids which take the place of the
atmospheric air in the different sorts of asphyxia, appear to act
very differently upon the tonic powers, or the insensible organic
contractility of the lungs. Some of these put a sudden stop to the
circulation, others not. Compare the asphyxiæ produced by nitrous
or sulphurated hydrogen gas, with those which may be occasioned
by pure hydrogen, or carbonic acid gas, and the difference will
instantly be seen. This difference indeed, as well as the various
other phenomena observable in the various asphyxiæ, depends on
causes which we have not mentioned, but the affection of the
air-cells, is evidently one of them.
Lastly, the third cause of stagnation of the blood in the
venous vascular system, is that debility, which takes place in
the ventricle and auricle of this system, when penetrated with
venous blood: on the influx of the blood from the cava, they
are consequently distended, and this is the case also with the
cava itself, for the very same reason. The causes which are now
assigned, are sufficient to shew why the black-blooded system, is
gorged with fluids in asphyxiæ.[88] The following considerations
will shew why the red-blooded system contains a lesser quantity of
fluid.
1st.--The obstacle commences in the lungs; therefore the aortic
heart must receive a less quantity than usual: hence, as we have
seen, proceeds the quicker cessation of the contractions of this
ventricle.
2dly.--The natural strength of the arteries, though enfeebled
by the influx of blood into their parietes, is much superior to
that of the veins, which besides are subject to the same cause of
debility.[89] Accordingly these vessels and the aortic ventricle,
are capable of surmounting the resistance of the capillary vessels
of the body in general, much more easily than the veins and the
venous ventricle, are of vanquishing the capillaries of the lungs.
3dly.--In the general capillary system, there is only one cause of
want of action, viz. the presence of black blood in it; to this in
the lungs there is added another cause, the want of that habitual
excitement which this organ receives on the part of the atmospheric
air: accordingly in the lungs, there is a greater resistance
offered to the influx of the blood, and with respect to the heart,
a less capability of surmounting such resistance. In the other
parts, the contrary of all this is observed, a less resistance to
the influx of the blood from the arteries into the veins on the
one hand, and on the other a greater capability of overcoming such
resistance.
4thly.--In the general capillary system, which is continued on from
that of the arteries, if the circulation be embarrassed at first,
in any organ in particular, it may still continue to go on in the
other organs, more or less, in which case the blood regurgitates by
these others into the veins. On the contrary, as all the capillary
system, which is the continuation of the general venous system,
is concentrated in the lungs, the venous circulation must be
suppressed, whenever this organ loses its powers.
The preceding considerations, if I am not mistaken, explain why
the vascular systems are so unequally full of blood after death, a
circumstance, which is common to almost every disease, as well as
the asphyxiæ.
In the latter sort of death however, although the general capillary
system presents a less degree of resistance than is made by the
capillary system of the lungs, nevertheless such resistance arising
from the influx of the black blood into the organs in general is
very manifest, and produces two remarkable phenomena.
The first is a greater quantity than usual of black blood in the
arteries, and therefore a greater difficulty of injecting these
vessels. Such blood is seldom coagulated. Indeed in all cases the
venous blood is much less coagulable than arterial blood. This fact
is proved, 1st, By the experiments of modern Chemists. 2dly, By the
comparison of the blood of varices with that of aneurisms. 3dly, By
the inspection of that which usually stagnates after death in the
veins of the neighbourhood of the heart.
The second circumstance, to which I have referred, is the general
livid colour of the greater number of the surfaces, with the
fulness of divers parts, such as the face, the tongue and lips.
These two phenomena indicate a stagnation of the blood at the
extremities of the arteries, in the same way as they denote the
same effect in the pulmonary vessels; here there is a much more
evident repletion, because as I have said, the capillary system is
there concentrated within narrow limits.
The reflux of the blood of the veins towards the extremities is the
reason assigned by authors for the livid appearance of asphyxiated
persons. There is little reality in this cause: in fact, this
reflux, which is very sensible in the trunks of the veins,
diminishes continually towards their ramifications, where it is
impeded and rendered impossible by the valves, besides which, the
following experiment is an evident proof, that we must attribute
the lividity in question, to the impulse of the black blood from
the aortic ventricle.
1st.--Adapt a syringe with its stop-cock to the divided trachea.
2dly, Open the abdomen so as to distinguish the intestines and
epiploon. 3dly, Shut the cock. At the end of two or three minutes,
the red tint which animates the peritoneum, and which is borrowed
by this membrane from the vessels, which creep underneath it,
will be changed into a dull brown colour. This colour may be made
to disappear and re-appear at will, by opening or shutting the
syringe.
Here we cannot, as if the experiment were made upon other parts,
suspect that a reflux is propagated from the right ventricle
towards the venous extremities, since the mesenteric veins,
together with the other branches of the vena portæ, form a system
apart, independent of the great black-blooded system, and having no
communication with the cavities of the heart which correspond with
this system.
But I shall touch again upon this subject. The above experiment is
amply sufficient to prove, that the lividity of the surfaces of the
body is owing to arterial impulse.
At present we are in a condition to explain how the lungs are more
or less gorged with blood, more or less livid, and how the livid
spots upon the different parts of the body are more or less marked
accordingly as the asphyxia has been more or less prolonged: for it
is evident, that if before death, the black blood have gone round
the two systems ten or twelve times, it will inject the extremities
much more than if it had made such circulation only two or three
times; at each revolution, a greater or less quantity will be left
in the extremities, for want of action in the capillary vessels.
In finishing this chapter I shall take occasion to observe, that
the spleen is the only organ of the economy susceptible like the
lungs of assuming a very great variety of volume. Scarcely is
it ever found in the same state. It has been falsely supposed
that there is a relation between the plenitude or vacuity of the
stomach, and the inequalities of the spleen; but this is not the
case, as I have said elsewhere. Such inequalities during the life
of the body do not exist, and supervene only at the instant of
death.
It appears to me, that they depend especially upon the state of
the liver, the capillary vessels of which, are the continuations
of all the branches of the vena portæ as the capillaries of the
lungs are those of the great venous system. Thus, when the hepatic
capillaries from any cause whatever are enfeebled, the spleen
must swell and be filled with the blood, which cannot traverse
the liver.[90] In such case, if I may so express myself, there
is an isolated asphyxia of the abdominal vascular apparatus. The
liver being to the spleen, what the lungs are to the black-blooded
cavities in common asphyxia. The resistance is in the former, the
stagnation in the latter. But this matter may be better understood
hereafter. Experiments upon animals killed in different ways, would
throw much light upon it, and these I purpose undertaking. By these
means we may rigorously establish the analogy existing between
the stagnation of the blood in the different branches of the vena
portæ, and that which is observed in the general venous system,
in consequence of various kinds of death. With respect to the
spleen and its system of veins, in ordinary asphyxia, I have never
remarked in it any peculiarity.
FOOTNOTES:
[79] It is not because the vessels of the lungs have become
tortuous that the blood flows through them with difficulty, but
because they are compressed. It was needless for Goodwyn to seek
for reasons to prove, that the flattening of the lungs does not
offer a mechanical obstacle to the course of the blood. If he had
observed with attention the phenomena of respiration, he would have
seen that this contraction, if it does not completely interrupt
the circulation of the blood in the lungs, at least modifies it
in a very remarkable manner. When the lungs contract, not only
the bronchial cells are flattened, but the pulmonary vessels are
compressed, and tend to expel the blood contained in their cavity.
This fluid flows back then on one part towards the right ventricle
by the pulmonary artery, and on the other it accumulates in the
pulmonary veins before entering the left auricle. Hence we see that
the jet by the carotid artery must increase rather than lessen in
the last moments. But if the compression continues, as the capacity
of the ramifications of the pulmonary artery is diminished as
well as that of the veins of the same name, the quantity of blood
which passes through the lungs is less, and the jet by the carotid
necessarily decreases. The experiment related by Bichat is then
entirely opposed to the opinion which he advances.
It is not only by influencing the course of the blood in the system
of pulmonary vessels that the alternate motion of the thorax
modifies the circulation. If we lay bare the jugular vein of a dog,
we perceive that the blood does not move in its cavity from the
sole influence of the right auricle, but in an evident manner from
the influence of the motions of respiration also.
At each time that the thorax is dilated in inspiration, the vein
is quickly emptied, flattened and its parietes are sometimes
brought exactly against each other; it swells on the contrary and
fills with blood when the thorax contracts. A similar phenomenon
takes place in the venæ cavæ. In order to render it evident it is
sufficient to introduce by the jugular vein into the venæ cavæ a
sound of gum elastic; we then see that the blood flows through
the extremity of the sound only during the time of expiration. A
similar effect is observed if we introduce a sound into the crural
vein and direct it towards the abdomen.
Haller and Lorry have paid much attention to this phenomenon, and
have proposed an explanation of it which seems very satisfactory
at first view, though it is really imperfect. When the thorax is
dilated, say they, it draws the blood from the venæ cavæ, and, by
degrees, that of the veins which are near it. The mechanism of
this inspiration is very similar to that by which the air is drawn
into the trachea. When the thorax contracts, on the contrary,
the blood is crowded back in the venæ cavæ by the pressure which
is made on all the pectoral organs, vessels, heart and lungs, by
the expiratory powers, and by degrees arrives at the veins which
terminate in them. Hence the alternation of vacuity and fulness
which the jugular veins exhibit.
If we open an artery, and examine with attention the jet of blood,
we see that it increases in expiration, and this is especially
evident when the animal expires strongly or makes an effort; but
as we cannot always produce these efforts at will, or a great
inspiration, we can in some measure imitate the phenomenon and
produce the contraction of the lungs by compressing with the hands
the sides of the thorax; we see then the jet of arterial blood
increase or diminish, in proportion to the pressure that is made.
If respiration produces this effect on the course of the blood in
the arteries, it is natural to think that it can influence the
course of the venous blood, not only by means of the veins, as
Haller and Lorry thought, but also by means of the arteries. For
the purpose of satisfying myself, I made the following experiment,
I tied the jugular vein of a dog; the vessel became empty below the
ligature, and swelled much above, as uniformly happens. I punctured
slightly with a lancet the distended portion, so as to make a very
small opening. I obtained in this way a jet of blood, which the
ordinary motions of respiration did not modify evidently, but which
trebled or quadrupled in size if the animal made any considerable
effort.
It might be objected, that the effect of respiration was not
transmitted by the arteries to the open vein, but by the veins
which were free, and which would have transmitted the blood of the
venæ cavæ, towards the tied vein, by means of anastomoses. It is
easy to remove this difficulty; in fact, in the dog the internal
jugular vein is, as it were, but the appearance of a vein, and
the circulation of the head and neck is performed almost entirely
by the external jugular veins, which are very large. By tying
at the same time these two veins I was sure of preventing, in a
very great measure, the reflux which has just been spoken of;
but so far from the double ligature diminishing the phenomenon
before stated, the jet becomes on the contrary more strictly in
relation with the motions of respiration, for it was evidently
modified, even by common respiration; which, as we have seen, does
not happen in the case of a single ligature. In order to render
the thing more evident, I tried it on the crural vein; this vein
and all its branches being furnished with valves, which oppose
a reflux, if this phenomenon of the increase of the jet appears
during expiration, we might be sure that the impulse came from the
arteries. This is what I have observed in fact in many experiments.
The crural vein being tied and punctured below the ligature, the
jet which is formed increases evidently in powerful expirations, in
the efforts and the mechanical compressions of the parietes of the
thorax with the hands.
We see by this and the preceding experiments, that we cannot adopt
without modification the expression of Haller and Lorry relative to
the swelling of the veins. This swelling takes place, not only, as
they say, by the flowing back of the blood of the venæ cavæ into
the branches which open into them mediately or immediately, but
also by the entrance into the vein of a greater quantity of blood
coming from the arteries.
[80] As in dead bodies the air within and the air without are of
the same temperature, the lungs, when they are full of it, do not
flatten when the thoracic cavity is opened. There is usually then
a space between the parietes and the contained organs; this is not
because we die in expiration; for as the lungs empty themselves,
the ribs and intercostal muscles rest upon them; it is because
the pulmonary air, in cooling occupies less space, and the cells
contracting gradually as the cooling takes place, diminish the
whole size of the organ. A vacuum is then made between the pectoral
and pulmonary portions of the pleura.
It is thus that, under some circumstances, the brain flattening and
lessening after death, whilst the cavity of the cranium remains
the same, a vacuum is formed between these two parts, which then
exhibit an arrangement different from that of the living organs. If
the sacs without an opening, as the peritoneum, tunica vaginalis,
&c. never resemble, in this respect, the pleura and arachnoides; if
their different surfaces are always contiguous after death, it is
because the abdominal parietes or the skin of the scrotum, unable
to resist the external air, flatten by pressure, and are brought
against the internal organs, as the diminution of these tends to
form a vacuum.
It is to this vacuum existing in the pleura of dead bodies, that
must be referred the following phenomenon, which is always observed
when the abdomen is opened and the diaphragm dissected. In fact, as
long as no opening is made in this muscle, it remains distended and
concave, notwithstanding the weight of pectoral viscera which rest
upon it in a perpendicular situation, because the external air,
which presses the concavity of it, forces it then into the vacuum
in the thorax, which never exists during life. But the instant the
air is admitted by a cut of the scalpel, this muscular partition
flattens, because the equilibrium is established. If all the air is
drawn from the lungs by a syringe, the diaphragmatic arch is still
more evident.
There is then this difference between the opening of a dead body
and that of a living one, that in the first the lungs are already
flattened, and in the second they flatten at the instant of
opening. The contraction of the cells, from the condensation of
the air by cooling, is an effect of the contractility of texture
or from want of extension, which as we have said, continues in a
degree with the organs after death.
Besides, if the lungs flattened in the dead body the instant
the thorax was opened, it would be owing to the pressure of the
external air, a pressure which would expel through the trachea what
was contained in these organs. Now if, to prevent the escape of
air, you close hermetically the canal by fixing a tube to it the
stopper of which is tight, and the thorax is afterwards opened, the
lungs still flatten; the air had already gone out of them. Make,
on the contrary, the same experiment on a living animal, you will
always prevent the flattening of these organs, by preventing the
expulsion of the air.
In this point of view Goodwyn has gone on a wrong principle in
measuring in a dead body, the quantity of air remaining in the
lungs after each expiration. Besides, if you open bodies ever
so little, you will hardly find two in which there is the same
arrangement in the lungs. The infinitely various manner in which
life terminates, by accumulating more or less blood in these
organs, by retaining more or less air in them, &c. gives them so
variable a size, that no general data can be established respecting
them. On the other hand, can we hope to be more successful on the
living body? No; for who does not know that digestion, exercise,
rest, the passions, tranquillity of mind, sleep, watchfulness,
temperament, sex, &c. make an infinite variety in the forces of the
lungs, the rapidity with which the blood circulates through them,
and the quantity of air that penetrates them? All the calculations
on the quantity of this fluid which enters or goes out according to
the inspiration or the expiration, appear to me to be physiological
errours, inasmuch as they assimilate the nature of vital forces
with that of physical forces. They are as useless to science as
those which had formerly for their object the muscular force, the
velocity of the blood, &c. Besides, observe if their authors agree
better among themselves then they used to do on this much agitated
point.
[81] It is inconceivable how Bichat could think of confirming his
opinion by the example of hydrothorax. Who does not know that when
an effusion takes place in the cavity of one of the pleuras, that
that portion of the lungs only which is above the level of the
water serves the purposes of respiration; that when the effusion
has arrived to the summit of the cavity, the lungs of that side,
which can no longer dilate, are of no use in respiration; and
those of the other, being compelled alone to make the necessary
modifications in the blood, must be traversed by the greatest part
of this fluid? It is known, finally, that in this case the patient
cannot lie down an instant on the sound side, because this position
prevents the dilatation of the lungs of that side which alone
serve for respiration, and the danger of suffocation is therefore
imminent.
[82] The observation of Bichat is very just; and I have myself
often observed in cases of apoplexy, that the motions of the heart
continue many hours after the arteries contain only black blood.
[83] At the period Bichat wrote, it was impossible to know whether
the arterial or venous blood contained most hydrogen and carbon.
At the present day even, when the means of analysis are much more
perfect and animal chemistry farther advanced, we are hardly better
informed.
[84] It seems that when Bichat wrote this work, he had not fixed
in his own mind what part the arteries take in the circulation;
at least, in this paragraph, he seems to give them a contractile
power, which, in his other works, he accords only, to their
ultimate ramifications.
[85] It is certain, whatever Bichat may say concerning it, that
numerous angles in the course of a blood-vessel, by increasing
the friction, must retard the course of the fluid which runs
through its cavity. We may in fact believe that it is one of the
causes, which, in the flattening of the lungs, embarrass the
circulation; this cause exerts its action principally upon the last
ramifications of the pulmonary artery which, by their interlacing,
form the bronchial cells; another more powerful cause, which acts
equally on the divisions of the vein and the artery is, as we have
said, the pressure made on the lungs by the flattening of the
thorax, and the elevation of the diaphragm.
[86] See the article on the influence of the lungs on all the
parts. I am compelled here to deduce consequences from principles
which I shall prove hereafter; such is in fact the connexion of
questions which have the circulation for their object, that the
solution of one draws as a necessary consequence that of all the
others. It is a circle in which it is always necessary to suppose
something, leaving it to be proved afterwards.
[87] I cannot see what can have induced Bichat to admit this
erethism of the lungs, the use of which cannot be imagined. It
is quite enough to suppose in the organs the existence of those
concealed properties, when there is need of them to explain their
functions.
[88] As the blood flows in the veins in a continuous motion, the
distension of these vessels does not take place in the direct
motion of the blood, but in its retrograde motion. Every time the
right auricle contracts, a portion of blood, instead of passing
into the ventricle of the same side, is forced back into the
superior and inferior venæ cavæ, and into the principal venous
trunks which open into them. By this reflux of the blood, these
veins are dilated, and have a pulsation which is easily seen in the
jugular in very thin people. This pulsation has received the name
of the _venous pulse_. When it is very evident, it may indicate an
obstacle to the passage of the blood from the auricle to the right
ventricle.
Another reflux of the blood in the veins corresponds with the
moment of expiration, and is perceptible even longer. We shall soon
have to speak of it, in speaking of the _movements_ of the brain.
[89] _The natural force of the arteries_ is not dependent on life,
and consequently cannot be enfeebled by the entrance of black
blood. This force is nothing but elasticity, which indeed ceases to
be in action as soon as death takes place, but which does not cease
to exist till the texture itself is destroyed and disorganized. As
this property is very conspicuous in the arteries, it is sufficient
to drive the blood from their cavity at the instant of death,
whilst it is too feeble in the veins to expel this fluid entirely.
Thus it is, that we find blood in the veins only, after death.
[90] The state of the spleen in the dead body may become in some
measure an index of the state of the circulation during the last
moments of life. The swelling of it shows almost always the
embarrassment of the circulation; and not only in an insulated
system, such as that of the vena portæ, as Bichat considers it, but
in the whole pulmonary system.
When any cause impedes the circulation in the capillaries of the
lungs, it necessarily produces a stagnation of the blood in the
divisions of the pulmonary artery, and by degrees the disturbance
is felt even in the two venæ cavæ, but especially in the inferior
in which the blood rises against its gravity. The blood accumulates
in the principal branches; the veins of the liver and kidneys swell
more or less; as to these organs themselves, the firmness of their
texture hardly allows them to be distended, so they do not increase
sensibly in size, or if this increase takes place, it is slow.
It is not the same with the spleen; the looseness of its texture
will admit a great quantity of liquid, and its size can thus be
doubled or trebled in a very short time. It becomes then a kind
of reservoir, in which is accumulated the blood which cannot pass
through the lungs.
It may be objected to what we have just said, that oftentimes in
phthisis the greatest portion of the lungs has become incapable of
allowing the blood to pass, and that yet after death, the spleen
is found in a natural state. But it should be recollected, that
phthisical patients have, during the latter part of their lives,
but very little blood, so that each portion sent by the right
ventricle always finds a sufficient channel for it in the lungs.
CHAPTER VII.
OF THE INFLUENCE OF THE DEATH OF THE LUNGS OVER THAT OF THE BRAIN.
We have just seen, that in asphyxia, the movements of the heart are
paralyzed, because its fleshy fibres are penetrated with venous
blood. This fact should indicate the same to be the case with
reference to the action of the brain. It is indubitably proved by
experiment.
Whatever be the manner in which the pulmonary functions are
interrupted, it is always the interruption of the chemical changes,
which troubles the functions of the brain.[91] What I have said
upon this point with respect to the heart, is exactly applicable
to the cerebral mass: I shall not repeat it. It remains to shew
by experiment, and the observation of diseases, that when the
chemical functions of the lungs are put a stop to, it is the black
blood which interrupts the action of the brain and that of the
nervous system. In the first place let us examine our experiments.
I first began by transfusing into the brain of an animal, the
arterial blood of another, that this essay might serve as a point
of comparison for others. Open one of the carotids of a dog; tie
the extremity towards the brain, and fasten a tube to that which
is next the heart; then open the carotid of another dog, tie the
extremity of the vessel next the heart, and fix the other end of
the tube into that which is next the brain; then let the assistant,
who meanwhile should have had his fingers upon the artery of
the first dog underneath the tube, remove his compression, and
the carotid of the second dog will be seen beating under the
impulse of the blood injected from the heart of the first. This
operation fatigues but little the animal which receives the
blood, particularly if one of the veins be previously opened, to
prevent too great a fulness of the vessels. It will live very well
afterwards. This experiment has been often repeated, and always
with the same results.
After this experiment, I opened the carotid, and the jugular vein
of another dog, and after tying the extremity of the carotid next
the heart, received the blood of the jugular into a warm syringe,
and injected it into the brain. The creature appeared immediately
to be agitated, breathed quickly, and seemed to be in a state of
suffocation, similar to that of asphyxia. Its animal life became
entirely extinct; the heart, however, continued to beat, and the
circulation to go on for half an hour afterwards; at the end of
which time the organic life was terminated also.
This dog was of a middle size, and about six ounces of blood were
injected with a gentle impulse, for fear of that being attributed
to the shock, which ought to have been the result of the nature and
composition of the fluid. I repeated this experiment upon three
dogs the same day, and afterwards at different times upon others;
the result was invariable, not only as to the asphyxia of the
animal, but even as to the concomitant appearances.
It might be thought that out of its vessels, and exposed to the
contact of the air, the blood might imbibe a pernicious principle,
or be deprived of that which is requisite for the maintenance of
life. It might be imagined, that to this cause was owing the sudden
death of the dog, on the injection of the brain with venous blood.
To shew that this was not the case, I made a small opening in the
jugular of a dog, to which I adapted a moderately warm syringe,
and pumped the blood immediately from the vein.--It was afterwards
thrown into the carotid: the symptoms were the same as the
preceding, but less marked, and the death of the creature induced
more slowly.--It is probable, then, that the air when in contact
with the living blood without its vessels may alter it a little,
but the essential cause of death is still the same.
Hence it appears that the black blood either is not an excitant
capable of keeping up the cerebral action, or that it acts in a
deleterious manner, upon the brain. The injection by the carotid of
various other substances will produce analogous effects.
I have killed animals in this way with ink, oil, wine, and water
coloured with indigo. The greater number of the excrementitious
fluids, such as urine, bile, the mucus of catarrhs, occasion death
also by their simple presence on the brain. The serosity of the
blood is fatal, but not as quickly so. Now it is certainly upon the
substance of the brain, and not upon the internal surface of the
arteries, that these different substances exert their influence. I
have injected them all into the crural artery. In this way they are
none of them mortal, but occasion always a torpor, amounting even
to paralysis at times.[92]
The black blood is doubtless fatal to the brain, the brain becoming
at once a tonic from its presence. In what way does it act? I do
not pretend to determine the manner; for this were only to begin a
series of conjectures.
By this time we are authorised to conclude, that in asphyxiæ, the
circulation which continues for some time after the interruption
of the chemical functions of the lungs, interrupts the cerebral
functions, from its being composed of black blood only. The fact is
proved in another manner, for the movements of the brain continue
to be made as usual.
If the cerebral mass be exposed, and the creature asphyxiated, the
animal life will be extinguished, but the motion of the brain will
be apparent still. Since then the latter cause of life subsists,
the cause of death must be in the nature of the fluid, by which the
organ is penetrated.
Nevertheless, if any affection of the brain coincide with asphyxia,
the death which is occasioned by the latter, will be quicker than
is usually the case. Strike a dog a violent blow upon the head,
and then if he be deprived of air, he will die on the instant. In
asphyxiating another animal already in a state of stupor, from
compression of the brain, I observed that the vital functions were
interrupted somewhat sooner, than when the brain is untouched
during that operation; but the consequences hitherto deduced, may
be supported by other experiments.
If in asphyxia the black blood suspend the action of the cerebral
mass, it is evident that the black blood taken from the arteries
of an animal dying of asphyxia, and injected into the brain of
another, will be the cause of death.
The experiment will be found to succeed--cut the trachea, of a dog,
and tie it up hermetically; then in the course of two or three
minutes, open the carotid and receive into a syringe the blood,
which flows from the vessels; inject it into the brain of another
animal, and it will die.
The following experiment is very similar, but offers a somewhat
different result. 1st. Adapt a tube with a stop-cock to the trachea
of a dog, and a tube of silver to the carotid, next the head,
after dividing this vessel, and tie up the extremity towards the
heart. 2dly. Fix the other end of the tube to the divided carotid
of another dog next the heart, and tie the extremity of the vessel
towards the head. 3dly. Shut the cock of the tube in the trachea,
and the black blood of the one dog in a short time, will be
injected into the brain of the other.
The appearances above described will shortly afterwards succeed,
but not so soon as in the former experiment, and if the transfusion
be stopped, the animal which has been asphyxiated in this way,
may recover and live. In the preceding experiment he will always
die. It appears then that some extraneous pernicious principle is
imbibed by the venous blood, when in contact with the air. Observe
that for the latter experiment the dog from which the brain of the
other is to be injected, must be stronger and more vigorous than
the other. The reasons are evident.
I was desirous of trying whether the venous blood would not
be capable of keeping up the cerebral action, if reddened
artificially. For this purpose I opened the jugular and the carotid
of a dog, and received the blood of the vein in a vessel filled
with oxygen; it immediately became of a vivid purple, but on its
injection into the brain, the animal was very suddenly killed.
I was much surprised at this result, but ceased to be so on
remarking, that a great quantity of air was mixed with the fluid,
and that it arrived upon the brain, in a state of foam: now we
know that a very small number of bubbles are sufficient to kill an
animal, whether they be introduced on the side of the brain, or on
that of the heart.
From this reflection, I was induced to repeat my experiments
upon the injection of black blood, suspecting as I did that some
small quantity of air might in these cases have been contained
in the extremity of my syringe. I soon however recollected that
if this cause were real, it should produce the same effect in
every instance whatever were the fluid employed, now when water is
injected there is nothing of the kind observable.
We may be thus assured that the black blood is either incapable
of keeping up the action of the brain, or that it acts in a
deleterious manner upon that organ, from the very nature of the
principles, which it contains. From such datum it should appear
that the life of the asphyxiated person might be restored, by
pushing on into the brain a sufficient quantity of arterial blood,
but here we must make a distinction of two periods in asphyxia:
1st. That in which the cerebral functions are only suspended: 2dly.
That in which the circulation and the movements of the breast are
stopped (for this disease is ever characterised by the sudden loss
of all animal life, and consecutively by that of the organic life.)
Now, as long as the first period of asphyxia continues, I have
observed that, by the transfusion of red blood into the brain, from
the heart of another animal, the movement of the creature which
is dying will be restored by degrees, and the cerebral functions
resume in part their activity; but this is only a temporary thing,
and the animal will fall again into its previous dying state, if
the asphyxiating cause be continued.
On the other hand, if during the first period, to which we have
alluded, the air be readmitted, into the trachea, the lungs will
be reanimated, the blood be coloured, and the creature be revived
without the assistance of any transfusion; and such transfusion
again is of no avail, after the second period of asphyxia, so that
this experiment offers only a proof of what we already know; with
respect to the difference of the influence of arterial and venous
blood upon the brain, and not a remedy in case of asphyxia.
Again, whenever I have injected venous blood into the brain, by the
help of a syringe, I have universally found that such proceeding
is fatal. Though the cause of asphyxia be removed, and arterial
blood injected, either with the syringe, or immediately from the
heart of another animal, it is of little effect, and frequently
of none whatever. And in general asphyxia when produced by blood,
which has been taken from the venous system itself and pushed into
the brain is much more certain and more decided, than that which
is occasioned by ligature of the trachea, or the introduction of
different gases into the lungs.
After having established by different experiments, how fatal the
influence of the black blood is upon the brain, which receives it
from the arteries whenever the chemical functions of the lungs are
suspended, it will not be amiss or out of place to shew, that the
phenomena of the asphyxia, which are observed in the human subject,
accord with the experiments of which I have given the detail.
1st. It is generally known that every kind of asphyxia affects the
brain in the first instance; that the functions of this organ are
the first to be annihilated; that the animal life, and particularly
the sensations cease; that all our relations with exterior objects
are instantly suspended, and that the organic functions are only
consecutively interrupted. Whatever be the mode of asphyxia, by
submersion, strangulation, gases, or a vacuum, the same phenomena
occur at all times.
2dly. It is known that the greater number of those who have escaped
suffocation, have been sensible only of a general stupor, the seat
of which has been evidently in the brain. It is known also, that
death is almost always certain in these cases, while the pulse and
the heart have ceased to be felt.
3dly. It is affirmed by almost all such persons as have survived
this accident, especially when caused by the vapour of charcoal,
that the first thing of which they were sensible, was more or less
pain, in the head, an effect in all probability occasioned by the
first influx of the black blood into the brain. This fact has
been noted by the greater number of authors, who have written on
asphyxia.
4thly. The vulgar expression that “charcoal flies to the head” is
surely a proof that the brain, and not the heart, is the first
affected in the asphyxia occasioned by this deleterious substance.
The unprejudiced vulgar, oftentimes observe more correctly than we
do, who frequently see only what we wish to see.[93]
5thly. There are many examples of persons, who after escaping the
pernicious effects of the vapour of charcoal, have been subject
afterwards to paralytic affections, and loss of memory. Such
changes have evidently their seat in the brain. Convulsion also
is frequently the effect of the impression of mephitic vapour:
head-ache is a common symptom, and for the most part remains after
the others have disappeared. In every book of cases may be seen
examples of these affections.
In cold-blooded animals, and in reptiles especially, this
influence of the black blood on the brain, though real, is much
less apparent. Make an incision into both sides of the breast of
a frog, then tie the lungs at their root, and the animal will
live notwithstanding for a considerable time. Cut away the lungs
entirely, and the same phenomenon will be remarked. In fish, the
relation between the lungs and the brain, is somewhat more direct,
for by the organization of the branchiæ, they differ essentially
from reptiles. I have taken away the cartilaginous plate which
covers the gills of the carp, the motion of the gills however
continued to be made as before, and the animal lived without any
apparent injury done to its functions. I afterwards put a ligature
about the cartilaginous rings which sustain the branchiæ, so as to
hinder all motion in the pulmonary apparatus. The effect was, that
the animal languished, his fins dropt, his muscular movements soon
grew weak, then ceased entirely, and the creature in the course
of a quarter of an hour was dead. The same phenomena with some
little variety, were observable in a carp from which I cut away the
branchiæ.
After all however, the particular nature of those relations, which
unite the heart, the lungs, and the brain, both in the red and
cold-blooded animals, is well worthy the farther investigation of
physiologists. The latter sort of animals, can neither be subject
to syncope or apoplexy, or at least the character of these diseases
must be very much modified in them. They are with much more
difficulty asphyxiated. We shall now return to those species which
bear a nearer resemblance to man.
From the influence of the black blood over the heart, the brain,
and the rest of the organs, it was my opinion, that persons
affected with varicose aneurisms, would perish less quickly from
asphyxia then others; because the red blood passes into the veins,
and traverses the lungs without requiring alteration. Accordingly,
it should be capable of keeping up the cerebral action.
To be assured if this suspicion were well founded, I made a
communication between the carotid artery and jugular vein of a
dog, by means of a curved tube. The pulsation of the artery was
thus communicated to the vein. I afterwards asphyxiated the animal
by stopping the trachea, but the phenomena of death were little
different from those of common asphyxia.
We may conclude with certainty, from the various considerations and
experiments presented in the present chapter.
1st. That when the chemical phenomena of the lungs are interrupted,
the black blood acts upon the brain, as it does upon the heart,
by penetrating the tissue of that organ, and depriving it of the
excitement, which is necessary to its action.
2dly. That its influence is much more rapid upon the first, than on
the second of these organs.
3dly. That it is the inequality of such influence, which occasions
the difference in the cessation of the two lives in the case of
asphyxia. The animal life is always annihilated before the organic
life.
We may conceive from what has been said in this and the preceding
chapter, how unfounded are the suspicions of those who have
supposed that the brain, after the separation of the head from
the body by the guillotine, might live awhile and have sensation.
The action of this organ is immediately connected with its double
excitements.--1st, By motion; 2dly, By the nature of the blood
which it receives. Now, when the interruption of such excitement
is sudden, the interruption of every kind of feeling must also be
sudden.
When the chemical functions of the lungs are suspended, the
disturbance induced in the functions of the brain, has indeed a
very considerable influence on the death of the other organs;
nevertheless, such disturbance is the beginning of death only in
the animal life, and even then is connected with other causes. The
organic life ceases from the sole presence of the black blood among
the different organs. The death of the brain is only an isolated
and partial phenomenon of asphyxia, which does not take place in
any particular organ, but in all alike. We shall explain this
assertion in the following chapter.
FOOTNOTES:
[91] In a preceding article, Bichat maintains that the entrance of
the arterial blood contributes to support the action of the brain,
principally by the jar which it communicates to this organ. It is
astonishing, after this, that he should attribute the suspension
of the cerebral functions to the interruption of the chemical
phenomena of respiration rather than to that of the mechanical
phenomena. He could not however be ignorant, that it is to the last
that must be referred the greatest of the two motions with which
the brain is constantly agitated.
These motions of the brain in relation with those of respiration
have been for a long time observed. Schitling has described them
in a memoir inserted in the first volume of the Memoirs of Learned
Foreigners. He has shown that the brain rises in expiration, and
flattens in inspiration. Haller, Lamure and Lorry have since him
investigated this motion, and they have given an explanation of
it, which is defective only because they have been ignorant of the
influence of respiration on the acceleration of the course of the
blood in the arteries through the medium of the capillary vessels.
At the time of a strong expiration, all the pectoral and abdominal
organs are compressed, and the arterial blood is forced more
especially into the branches of the ascending aorta. This blood
goes then in greater abundance towards the head, and has a tendency
to pass more quickly in the veins which carry it towards the heart;
which would take place immediately if the veins were free. But the
pressure made on the pectoral organs has also made the venous blood
flow back in the vessels which contain it. Now, this blood has just
met that which comes from the arteries; the vessel is distended,
and the course of the fluid is arrested in the veins; from that the
brain swells and rises up; but as soon as expiration has ceased,
the dilatation which takes place in the chest attracts, in some
measure, the blood of the superior venæ cavæ; the veins which enter
it are soon emptied and the brain flattens down.
In reflecting on the mechanism by which this movement of the brain
is effected by the influence of respiration, we cannot perceive
why the phenomenon should be limited to the organ contained
within the cranium, and especially why the spinal marrow should
not equally partake of it. The continuity of this organ with the
cerebrum and cerebellum, its situation in a cavity which it does
not entirely fill, the numerous arteries which it receives from
the intercostal and vertebral arteries, the number and size of its
veins destitute of valves are so many circumstances which should
favour the accumulation of the blood at the time of expiration, and
consequently produce its swelling. For the purpose of seeing if my
conjectures were well founded, I have made some experiments; I laid
bare in a young rabbit the spinal marrow at about the eighth or
ninth dorsal vertebra, I saw it perfectly whole and surrounded by
its coverings. At first I perceived no motion, but soon the animal
being much incommoded by the position in which I kept him, made
a deep inspiration, and then I saw distinctly the spinal marrow
flatten, and a small vacuum between the dura mater and the osseous
parietes of the vertebral canal. In the following expiration, the
spinal marrow resumed its original size. I was unable to see any
thing more in this animal.
I laid bare in a dog of middle size, the spinal marrow, a little
above the lumbar region; I could not mistake there a very evident
motion, in relation with respiration: a flattening during
inspiration, and a swelling during expiration. The phenomenon was
so marked, that the air entered the vertebral canal with a noise,
whilst the animal inspired, and was forced out when the animal
expelled the air from his lungs.
For the purpose of satisfying myself that this motion took place in
the spinal marrow and not in the dura-mater, I cut this membrane in
the whole extent of the opening made in the vertebral canal, and
I was able easily to convince myself that the motion was from the
swelling of the spinal marrow. I am not however certain that there
is not a slight rising of the organ from the dilatation of the
large veins in the anterior part of the vertebral canal, but this
dilatation cannot be considerable, on account of the fibrous layer
which covers the posterior face of these veins.
[92] Active substances introduced into the veins can act on the
organs in many ways at once. They have at first their peculiar
action which is nearly uniform, whatever may be the mode of
administration; but they produce also other effects resulting from
their physical properties, and these last may vary according to the
form in which they are introduced.
The substances introduced into the circulation have necessarily
to pass through a double system of capillary vessels, and must
consequently be very greatly subdivided. Hence we see that a viscid
fluid would be unable to enter the smallest vessels, and that by
remaining in those which can admit it, it will prevent the passage
of the blood, and occasion a congestion either of the lungs or
some other organ, according as it has been injected into a vein
or an artery. A substance like quicksilver, which without being
viscid, exhibits great cohesion among its particles, will produce
precisely the same effects. The globules will never divide below a
certain size. The air itself, mixed in a fluid such as the blood,
will form bubbles which will divide with more difficulty as they
become smaller, and which can finally stop in the entrance of the
capillaries, so as to prevent a free passage of blood in a part
of these vessels. Boerhaave thought that it was always thus, by
opposing a mechanical obstacle to the capillary circulation of the
lungs, that air injected into the veins produced the death of the
animal.
In an experiment in which I proposed to myself to change the nature
of the blood by a foreign fluid, I injected into the jugular vein
of a dog, an ounce of Olive oil, thinking that this substance would
circulate without inconvenience with the blood; but it was not so,
and the animal died in a few minutes after the injection.
In examining the organs after death, I saw that the oil had closed
the last ramifications of the pulmonary artery, and that it had
also stopped the circulation and respiration, by preventing
the passage of the blood to the left side of the heart, by the
pulmonary veins. An injection made with a thick solution of gum
tragacanth produced precisely the same phenomena as the oil.
An inert, impalpable powder, suspended in water, immediately
produces death, if injected into the jugular vein, because it shuts
up the last divisions of the pulmonary artery.
If the injected substances are not divided at first in the blood,
so as to spread uniformly into the different branches, death does
not take place so quickly, because a part of the sanguineous
canals remains free for the circulation. This is the case when we
inject quicksilver or air in so small a quantity as not to produce
instantaneous death. The congestion, in this last case, is often
alone sufficient to produce it after a certain time; in the other
case, there is added to the obstruction a real pneumonia caused by
the presence of quicksilver in the obliterated vessels. We shall
now relate four experiments of M. Gaspard, which will show the
effects of the stagnation of this fluid in different organs.
“_First Experiment._ I introduced into the jugular vein of a small
dog, four days old, thirty six grains of quicksilver purified
through goat’s skin. Soon after he refused to suck, lost his
vivacity, motility and heat, had dyspnoea and fever, and died at
the end of twenty four hours, having been all the time much colder
to the touch than the other pups with whom he was. On opening the
thorax, the lungs were found much inflamed, almost hepatized,
heavy, puckered up and full of mercury.”
“_Second Experiment._ I injected into the left carotid artery of a
sheep, very near the brain, half an ounce of mercury with water;
I then tied with a double ligature the open vessel. The animal
immediately manifested pain, and was for an instant immoveable, the
head inclined, with stupor and a prominence of the eyes, which were
extraordinarily open; then bending on the fore legs, twisting of
the head and neck on the right shoulder, with a kind of stiffness
or convulsive elasticity, which was always present till death, and
returned, as by the effect of a spring, when I straightened the
neck. Two hours after, standing impossible, state of drowsiness,
some convulsive motions of the limbs, the left eye swelled, red and
inflamed. The next day, the same state, almost total annihilation
of the animal or external life, copious excretion of mucus by the
left nostril, the eye still very large and inflamed. The third day,
the same state; death took place fifty hours after the injection.
On examination of the body it was found that the left eye was in a
state of suppuration and contained mercury; the thyroid, pharyngeal
auricular, lingual, labial, nasal and cerebral arteries of the
left side, were admirably injected with this metal which run out
under the instrument; but their capillary terminations contained
none of it, and we could see to what ramification, to what sized
caliber it had penetrated, and the point where it was unable to
pass; the left nasal cavities exhibited a very pretty reticulated
appearance, brilliant and silvery. Moreover all the organs of this
side were red, inflamed and swelled by the presence of the foreign
body, and it was curious to see the half of the thyroid gland, the
tongue, the cheeks and the lips thus red and inflamed to the median
line, whilst the other half was sound and pale; the left brain was
slightly inflamed and especially the plexus choroides. Besides, I
was unable to discover a globule of quicksilver in any of the other
organs.”
“_Third Experiment._ I forced with a pewter syringe into the
crural artery of a large dog, a drachm and a half of quicksilver
mixed with common water. The animal, immediately after the double
ligature, did not manifest any sign of pain, and walked, bearing
less on that limb, which was very sensibly cold, though not
paralyzed. But about an hour after, he refused food, manifested
by piercing cries acute pain, constant agitation, frequent change
of place, and a very evident state of suffering; the limb soon
after grew warm, became hot to the touch, with an obscure pulse
under the tendo Achillis. This state of fever and pain continued
the whole day and night. The next day, the limb was swollen and
exhibited a phlegmonous œdema preserving the impression of the
finger; the plaintive cries were continual. On the third day his
condition was still worse, and I then killed him from compassion
sixty hours after the injection. I had carefully noticed the matter
of the excretions, without discovering a particle of quicksilver
in them. On examination of the body, I could not discover it in
any organ, except the limb subjected to the experiment, which was
swollen, inflamed and oedematous in all its textures; we observed
abscesses in it of different sizes, containing quicksilver, pus,
sanies and much gas, coming from the incipient gangrene of the
parts; the metal usually occupied the centre of all the abscesses;
the mercurial globules flowed out when I cut the skin, the cellular
texture, the muscles and especially the small arteries, which
were admirably injected by it; gelatinous exudations occupied the
interstices of the muscles.”
“_Fourth Experiment._ I injected a drachm of quicksilver, that
had been passed through goat’s skin, into the mesentric vein of a
dog of middle size. The animal exhibited several severe symptoms
which I shall not mention, because they probably depended on the
opening of the abdomen and the inflammation that resulted from it;
perceiving that they would become fatal, I killed him by another
experiment, fifty two hours after the first. On opening the body, I
found all the mercury in the liver; each globule was the centre of
a small collection of pus, of which it was the cause; but the liver
was but slightly diseased, but little inflamed, and only blacker
and more gorged with blood than usual. The stomach contained an
unusual quantity of very green bile; I could not discover any
quicksilver in the other organs.”
We see from all these different facts, that it is necessary for
every thing that enters the circulation to arrive at it by very
narrow channels, and after having been, as it were, sifted by the
agents of absorption; this is one use of the absorbent organs that
has not as yet been noticed. These facts also throw light on the
properties of substances injected into the veins of animals, after
having been dissolved in oil. We can believe that when these oily
solutions are carried into the intestinal canal, they are not
absorbed till after they have been gradually changed into a kind
of emulsion, and we know that in this form fatty substances may
be introduced with impunity into the circulation. We can in fact
inject into the veins a large quantity of milk, and the portion of
butter which is suspended in it, will not produce the effects which
would necessarily result from it, if we injected this substance
pure and only rendered liquid by heat.
[93] Is it true that common people observe without prejudice?
Have they not, on the contrary, on several physiological and
pathological phenomena deeply rooted prejudices? It is besides a
very singular idea to wish to judge by the name which they give
to an affection, of the organ primarily affected. If we always
reasoned in this way the expression of _sick at heart_ which is
given to nausea, would assign to vomiting a wholly different nature
from what would be correct.
CHAPTER VIII.
OF THE INFLUENCE OF THE DEATH OF THE LUNGS OVER THAT OF THE ORGANS
IN GENERAL.
I have just shewn in what way the interruption of the chemical
phenomena which take place in the lungs, annihilates the functions
of the heart and brain. It remains me to shew, that the other
organs of the body are as much affected by such cessation; so
that asphyxia, as I have said, is a general disease, and not an
affection of any one organ in particular.
But before I proceed to analyze the effects of asphyxia upon the
organs in general, and consequently the mode of action of the black
blood upon them, it may be of use to explain the phenomena of the
production of this kind of blood, at the instant when the functions
of the lungs are suspended. This paragraph will possess, perhaps,
some interest; it might have belonged indifferently to either of
the preceding chapters.
I. _Exposition of the phenomena of the production of black blood,
when the chemical functions of the lungs are suspended._
It is known in general, that the blood is coloured in traversing
the lungs, that from black it becomes red; but this very
interesting fact, has not been hitherto the object of any precise
or rigorous experiment. The lungs of the frog, of which the air
vessels are large, and the membranes thin and transparent, would
serve very well for the purpose of observing the process of the
phenomenon in question, but for the slowness of respiration in
these animals, the difference of organization in their lungs, and
the too small quantity of blood by which they are traversed. On
such account there can be little analogy between them and the more
perfect animals, and then again our experiments upon these little
amphibiæ, are all of them rendered incomplete, by the tenuity of
their pulmonary vessels, and the impossibility of observing the
correspondence of the change of velocity in the circulation, with
the colour of their blood.
The phenomena of the respiration of man, and those of the functions
which are dependent on it, can be illustrated only by experiments
made upon animals with a double ventricle, with a complete
pulmonary apparatus, possessed of a temperature superior to that of
the atmosphere, and the two separate systems of venous and arterial
blood; but on the other hand, in the mammalia resembling man, their
respiratory apparatus, the thickness of the vessels and cavities
of the heart, impede the view of the blood which they contain;
and experiments made without an absolute inspection of the fluid
there, can only give us approximations. The indecisive experiments
of former physiologists on this subject were my motives for the
present inquiry.
One of the best methods of judging of the colour of the blood,
consists as I have often said, in fixing a tube with a stop-cock
to the trachea. By this, the influx of air into the lungs, may
be regulated or altogether stopped. By this, we may distend the
organ, or entirely evacuate it; it gives us also the facility
of introducing whatever gas we please. The animal breathes very
well by such pipe when it is open, and would live with it for a
considerable length of time without any very great alteration in
its functions.
In the second place, an artery, the crural or carotid for instance,
must be opened with the view of observing the varieties of colour
in the blood projected from it. A small artery should not be
chosen. From such a one the course of the blood would be suspended
by the slightest accident; and on the other hand, the larger
arteries expend in a little time too large a quantity of blood;
this inconvenience may be remedied, by adapting to these vessels a
tube of a small diameter, or a stop-cock.
All things being thus prepared, on a dog, for instance, let us
see what are the phenomena which take place, when the colour of
the blood is altered. In my indication of these, however, I shall
speak only of what I have seen, and by no means pretend that in
man their duration should be similar or uniform, or even that in
animals of the same species, under the different circumstances of
sleep, digestion, exercise, and passion, &c. if it were possible in
such way to repeat them, they should be alike. The instability of
the animal functions, as I have said, is extreme; they cannot be
submitted to calculation; they remain indeed the same, but their
variations as to plus or minus are innumerable.
Let us now return to our subject:
1st. If the cock of the pipe be shut immediately after the animal
has inspired, the blood begins to be altered in colour at the
end of about thirty seconds.--At the end of a minute its colour
is dark; at the end of a minute and half or two minutes, it is
perfectly similar to venous blood.
2dly. If the cock of the pipe be shut immediately after the animal
has expired strongly, the blood receives its tinge of black some
seconds the sooner.
3dly. If the air of the lungs be pumped out entirely with a
syringe, the blood will suddenly pass from red to black.[94] In
such case it appears that the artery immediately throws out a black
stream, after it has expelled the red blood which it previously
contained. There is no gradation. The blood is expelled by the
arteries, such as it is in the veins.
4thly. If, instead of making a vacuum in the lungs, we inflate
the air cells to the full, the blood is a longer time in becoming
black, a minute at least, and is not completely black before the
end of three minutes.--This will vary according to the quantity of
air injected.
From all these experiments it follows, 1st, That the length of
the interval, during which the blood retains its red colour, is
in direct proportion to the quantity of air contained in the
lungs; 2dly, That as long as there remains any quantity however
small of respirable air in the cells of the lungs, the blood will
preserve more or less of its crimson colour; 3dly, That this colour
diminishes in proportion as the respirable air diminishes; and
4thly, That the blood is exactly similar to that of the veins,
as soon as the whole of the vital air in the extremities of the
bronchiæ has been exhausted.
In my different experiments with regard to asphyxia, I have
remarked, that if after shutting the cock of the syringe, the
animal agitate the chest by similar movements to those of
inspiration and expiration, the blood is a longer time in losing
its red colour, than in the case where the breast remains at rest.
Such motion and agitation must cause a circulation of air in the
cells, in consequence of which, a greater number of its points must
be presented to the circulating fluid. My experiments which I shall
presently detail on the breathing of animals in bladders, will
prove the truth of the above explanation.
At present I pass to a contrary set of phenomena--to those which
are exemplified when the blood regains its arterial colour during
the period, which, from a state of asphyxia, restores the animal to
life.
1st. When the cock, which for some minutes has been shut, is
opened, the air immediately penetrates into the bronchiæ; but
previously the animal expires strongly. Six or seven large
inspirations and expirations follow each other precipitately. The
artery being now examined, a jet of a very vivid colour is seen
succeeding to the efflux of black blood, and takes place in thirty
seconds at most, from the time of opening the tube. This is the
inverse of the phenomenon above described. There are no successive
shades perceived from black to red; the passage is instantaneous.
The brightness of the colour seems even to be greater than is
natural.
2dly. If instead of suddenly turning the cock, a very strong stream
of air only be admitted, the colour is less lively indeed, but just
as quickly regained.
3dly. If there be adapted to the stop-cock a syringe full of air,
and this fluid be pushed into the lungs, on opening the pipe, and
then the pipe be suddenly shut again, the blood will become red,
but much less evidently so, than when the entrance of the air is
owing to voluntary inspiration. Here the portion of air injected
must repel into the bottom of the cells whatever is already
vitiated, while on the contrary, if the tube be simply opened, the
vitiated air is at once rejected, and then replaced from without.
The following experiment appears to confirm this idea.
4thly. If instead of pushing air upon that which is contained in
the lungs, we pump out the vitiated air in the first place, and
then inflate the organ, the colouring process will be more rapid,
and the colour of the blood itself especially, more lively than in
the preceding case, though less so than in the first of this latter
suite of experiments.
5thly. The lungs being exposed on both sides by a lateral section
of the ribs, the circulation will continue to go on for a certain
time. Now, if by means of a syringe adapted to the stop-cock in
the trachea, the pulmonary vesicles be alternately emptied and
dilated, the changes from red to black, and from black to red, will
be observed as in the above experiment, as long as the circulation
lasts.
The following consequences may be inferred from the facts, which I
have mentioned.
1st. The rapidity with which the blood becomes red again, on
opening the pipe in the trachea, is a plain proof, that the
principle from which this colour is gained, must pass into the
blood across the membranous parietes of the air cells, and not by
means of the absorbents. I shall establish this fact hereafter upon
other proofs.
2dly. The celebrated experiment of Hook, in which the enfeebled
movements of the hearts of animals in a state of asphyxia are
accelerated by injecting air into the lungs, is very well
explained. The red blood penetrates into the fibres of the heart,
and puts an end to the debility induced, by the influx thither of
the black blood.
3dly. I do not believe, that motion can ever be restored to the
heart, when once it has been wholly annihilated by the presence of
venous blood. In this I have never succeeded, though I have often
attempted it. Many authors, however, pretend to have done so. If
the heart be reanimated by arterial blood, it is necessary at any
rate, that such blood, should pass into it, now in what way can it
arrive there, if the circulation have entirely ceased.
We must observe, however, that there are two cases of interruption
in the action of the heart from asphyxia. Sometimes there
supervenes a syncope which arrests the movement of this organ,
before the black blood has been able to produce such effect; and
here it is manifestly capable of excitement, from the presence of
the red blood, just as it is from the application of any irritating
cause; but when it has been injected with venous blood, it then
contains within itself the principle of its inertia, which can be
removed only by the contact of arterial blood with it; but such
contact is become impossible.
I was very desirous of knowing what the influence might be of
the different gases when inspired upon the colour of the blood.
Accordingly I successively adapted to the pipe different bladders,
containing hydrogen and carbonic acid gas.
The animal alternately swells and contracts the bladder by the
different motions of the thorax. It is calm at first, but at the
end of three minutes, begins to be agitated; its respiration
is now hurried and embarrassed, and at the end of four or five
minutes, the blood of the carotid is black.
Whichever of the two gases be employed, there is little difference
in the above phenomena. This remark should be compared with those
of the Members of the Institute, who have assured us that complete
asphyxia supervenes only after an interval of ten minutes, with
pure hydrogen, and at the end of two minutes with carbonic acid
gas. The black blood must continue, therefore, to circulate for a
longer time in one than in the other kind of asphyxia here spoken
of. This circumstance confirms some reflections which I shall have
occasion to offer upon the difference of asphyxiæ.
For what reason should the blood be a longer time in losing its
colour, when bladders of non-respirable air are fixed to the pipe,
than when the cock is simply turned? The reason of this is evident.
By the different motions of the lungs, the air is expelled and
reabsorbed, the respirable portion of it must consequently be
successively presented to the capillary orifices, by which it is
transmitted to the blood.
On the contrary, when the pipe is simply shut, the air it is plain
has not the same influx and efflux; in comparison with such motion,
it may be said to stagnate so that the respirable portion of that
which is enclosed in the bronchial cells is exhausted, and the
blood ceases to be coloured, though there remain in the trachea
and its larger divisions, a considerable quantity of fluid, which
has not been despoiled of its vivifying principle. Of this we may
be certain, after the death of the animal, by cutting the trachea
under the pipe, and plunging a bougie into it. The process by
which the blood gains its red colour appears to take place only at
the extremities of the bronchiæ, the inner surface of the larger
aerial vessels, has nothing to do with this phenomenon.
We may convince ourselves of the reality of the explanation which
I have offered, if we pump out the air of the lungs, before we
fit the bladder to the trachea; for in such case, the animal
must breathe the air of the bladder without mixture. Here the
change of the blood to black is almost sudden, but here also, as
in the preceding experiment, there is little difference in the
phenomena, whatever gas we employ. I have chosen the two gases
above mentioned, because they enter into the phenomena of natural
respiration.
When we adapt to the pipe a bladder full of pure oxygen, the blood
is very long in becoming black, but does not at first assume a
redder tint than it usually has.
II. _The blood which has been blackened in consequence of the
interruption of the chemical functions of the lungs penetrates into
the organs, and circulates for some time in the vascular system of
the red blood._
We have just established what are the phenomena of the alteration
of colour in the blood, when the chemical functions of the lungs
are suspended. Before we consider the influence of this change
upon the death of the organs, let us prove, that they are really
penetrated by the blood when so altered.
I have proved it to be a fact, that the force of the heart subsists
for some time, notwithstanding the influx of the black blood into
it, and have shewn that the black blood is thrown out with a jet,
similar to that of the red blood, &c. &c. Hence I might already
conclude, 1st, That the arterial circulation continues for a
certain time, though the arteries contain a fluid, to which they
are not accustomed, and 2dly, That the necessary consequence of
such circulation, must be the injection of the different parts
of the body with black blood; but we shall deduce the latter
conclusion from precise and rigorous experiments. To be certain
of this important fact, we have only to expose successively
the different organs, while the animal is suffering a death of
asphyxia. I have in this way examined the muscles, the nerves, the
membranes and the viscera. The following are the results of my
observations.
1st. The colouring matter of the muscles, exists in the body in two
states--at liberty, or in a state of combination; in the vessels,
where it circulates with the blood, or in the fibres, with which it
is combined. It forms especially the colour of the muscles, and in
such state undergoes no alteration from asphyxia; in its free state
it is blackened. The divided muscles furnish an infinity of black
drops, which are no other than indices of the divided vessels. Such
drops contrast with the red of the muscles; but when circulating
within them, are the cause of that livid tint which they then
present.
2dly. The nerves are habitually penetrated by a number of small
arteries, which creep along within their tissue, and carry to them
both excitement and life. In the state of asphyxia the black blood
by which they are traversed, is announced by the dull brown, which
succeeds to the rosy-white, which is natural to them.
3dly. There are few parts, where the influx of the black blood
is more visible, than in the skin; the livid spots so frequent
in asphyxia, are only the effect of the obstacles which it meets
with, in its passage towards the general capillary system, to the
organic contractility of which it is not a sufficient excitant. To
this cause also is owing the tumefaction of certain parts, such as
the cheeks and lips. This phenomenon we have seen already in the
lungs, they cannot be traversed by the blood and therefore become
in the last moments of life, the seat of a fulness, which affects
the whole of the capillary system there; but for the reasons,
which I have assigned, such fulness is always more evident in
the capillary system of the lungs, than in that of the system in
general.
4thly. The mucous membranes also, when the chemical functions of
the lungs are interrupted, exemplify a similar phenomenon. The
swelling of the tongue, observable in those that have been drowned
or hanged, or asphyxiated by the vapour of charcoal, the lividity
of the membrane of the mouth, of the intestines, and the bronchiæ
which have also been remarked, depend on no other cause. The
following is a proof of this assertion:
Drag out of an animal a portion of the alimentary canal and divide
it in such way as to expose its inner surface. Then shut up the
pipe which has been previously adapted to the trachea, and at the
end of four or five minutes, a brown tint will succeed to the red
one, which is natural to this surface.
5thly. I have made the same remark upon the fleshy granulations of
a wound, inflicted on an animal, for the purpose of observing the
manner in which they are coloured by the black blood. In the two
last experiments, this phenomenon is slower in taking place than in
many other circumstances.
6thly. The alteration of colour in the serous membranes is much
more quickly effected than it is in the mucous membranes. Of this
we may assure ourselves by comparatively examining the outer and
inner surfaces of the intestines, while the pipe in the trachea is
shut; in the serous membranes, the livid tint which they assume,
depends upon the vessels, which creep underneath them, and not on
the blood by which they are penetrated. Now as these vessels are
considerable, the black blood must flow into them almost as soon as
it is produced. In the mucous membranes on the contrary, and in all
cicatrices, the colour which they take on in asphyxia, is made by
the capillary system of the membrane itself, which system is much
more tardy than the other, to receive the black blood, and to be
penetrated by it; so much so indeed, as to refuse it in some parts.
I have many times seen the membrane of the nasal fossæ very red in
asphyxiated animals, while that of the mouth has been quite livid,
for there are parts into which as I have said the black blood will
not penetrate at all, and then they preserve their natural colour.
2dly. There are others into which it evidently passes, but where it
stops, and then a simple change of colour is observed, if it have
penetrated but in small quantity; and again, if it have penetrated
in a considerable quantity, together with such change of colour,
there will be observed a tumefaction of the part. 3dly. In other
cases, the black blood merely traverses the parts, without stopping
in the capillary system, and passes at once into the veins, as the
red blood does.
In the first and second case, the general circulation experiences
an obstacle which puts a stop to it in the general capillary
system. In the third, which is much more universal, it is in the
capillaries of the lungs that the blood is at last arrested, after
having circulated in the veins.
These two sorts of impediment coincide with each other, in many
instances. Thus in asphyxia, a part of the black blood which
circulates in the arteries stops in the face, upon the mucous
surfaces, in the tongue, and in the lips, while the other, and much
the larger quantity, finds no impediment in the general capillary
system, and is finally arrested in the lungs.
What is the reason, why certain parts of the capillary system
refuse to admit the venous blood, or if they admit it, do not pass
it on to the veins; while others are less enfeebled by it, and
transmit it as freely as ever. All this must certainly depend on
the relation existing between the sensibility of each part and the
venous blood.
I was desirous of making use of the power, which we possess, of
changing the colour of the blood, for getting some insight into the
influence of the circulation of the mother, upon that of the fœtus;
accordingly I procured a bitch big with young, and asphyxiated
her, by closing a tube, adapted to the trachea. About four minutes
after she had ceased to breathe, I opened her; the circulation was
going on. I then cut into the matrix, and exposed the cord of two
or three of the fœtuses. The artery and the vein, were both of them
full alike of venous blood.
Had I been able to procure other bitches in a similar state, I
should have repeated this experiment in another manner. I should in
the first place have compared the natural colour of the vein, with
that of the artery. In many of the young of the guinea pig, the
difference appeared to me to be much less than it is in the adult
animal. In many circumstances indeed I could perceive no difference
whatever. Both the arterial and venous blood were equally black,
though the respiration of the mother was in no wise impeded by the
opening of the belly. Secondly, I should have closed the tube in
the trachea, and then have observed whether the change in colour
of the umbilical artery of the fœtus (supposing the blood of the
artery to be different from that of the vein) were correspondent
with that, which would inevitably take place in the blood of the
mother. Experiments made with a view to these circumstances, and
on large animals, might probably throw much light upon the mode of
communication, between the mother and the fœtus. Observations are
also much to be desired, with respect to the colour of the blood in
the human fœtus, and the cause of its passage from a livid colour,
to the very marked red which it assumes, some little time after
birth.[95]
I might add a number of examples to these, which I have already
related of the blackening of the organs by the venous blood. Thus,
the kidney of a dog exposed, while the animal is dying of asphyxia,
is much more livid than in its natural state, the spleen also and
the liver, when divided, emit only black blood, instead of that
mixture of red and black blood which is observable, in the section
of these organs, upon an animal which breathes freely.
But I trust that we have facts enough to establish it as a
certainty, 1st, That the black blood after the interruption of
the chemical functions of the lungs, continues for some time to
circulate, and 2dly, That it penetrates into the organs, where it
replaces the red blood; these circumstances explain the reason, why
on opening the body we always meet with black blood even in the
vessels which are destined for the circulation of arterial blood.
In the last moments of existence of whatever death the individual
may have died, we shall always observe the lungs become embarrassed
and cease to perform their office, for some time previous to the
total suspension of the functions of the heart. The blood makes its
circle through the system, after ceasing to receive the influence
of the air, and consequently in its venous state; accordingly
it must remain so in the organ in every case, although the
circulation be much less evident, than in asphyxia, for it is in
this circumstance that consists, the great peculiarity of asphyxia.
The following phenomena may now be easily understood.
1st. When the left auricle and ventricle together with the large
divisions of the aorta, on opening the body, are found to contain
blood, such blood is always black. The fact is familiar to those
who are in the habit of dissecting. In exercising my pupils on the
surgical operations, I have always observed that when the open
arteries are not entirely empty, their contents are composed of
venous blood.
2dly, The corpus cavernosum is always gorged with this sort of
fluid, whether flaccid or in a state of erection. For I have seen
it in the latter state in two subjects brought to my amphitheatre.
One of these men had hanged himself, the other had died of
concussion of the brain.
3dly, The blood which is found in the spleen is never red; but
sometimes on the exterior, and sometimes on the concave surface of
this organ, I have observed spots of a scarlet colour, for which I
cannot account.
4thly, After death, the mucous membranes lose the red colour by
which they are characterized during life. They assume a black and
livid hue.
5thly, Blood extravasated in the brain of persons in a state of
apoplexy, is almost always found to be black.
6thly, Sometimes, instead of accumulating inwardly the blood
injects the surface of the body. In such case the face, the neck,
and shoulders swell, and are infiltrated with blood. I have
frequently remarked this sort of phenomenon in the subject, but
have never found it coincide with any internal extravasion.--The
colour of the skin is then of a purple or deep brown, an evident
sign of the sort of blood with which it is injected, and is
evidently produced by the stagnation of the black blood in the
external capillary system, not by the reflux of the blood from the
veins.
I shall not dwell any longer upon the numerous consequences of the
above established principle. I shall only observe, that when death
commences by the circulatory system, the preceding phenomena are
not to be remarked, or at least very little perceptible.
Let us now pass on to the influence of the black blood upon the
organs of which it penetrates the tissue.
III. _The black blood which penetrates the organs, as soon as the
chemical functions of the lungs have ceased, will not maintain them
in a state of life and activity._
To determine what the influence of the black blood is upon the
organs, I shall first remark, that the property of the red blood is
to stimulate them, and keep up their vital actions. This will be
proved by the following observations:
1st, Compare phlegmon, erysipelas, and inflammatory tumours (to
the formation of which the red blood is essentially requisite)
with scorbutic spots, and petechiæ, produced by the black blood.
The first will be found connected with the exaltation of the vital
powers, the second with their depression.
2dly, Examine two men, the one with a rosy coloured skin and large
breast, announcing vigour of lungs, the other with a pale and
sallow countenance, and narrow chest: in these the vigour of the
chemical combinations which are made in the lungs, should certainly
be very different.
3dly, The greater number of gangrenes in old men, begin with a
lividity in the part, a lividity which is evidently the index of
the absence or diminution of the arterial blood in the part.
4thly, The redness of the branchiæ of fish is always the sign by
which their vigour may be recognised.
5thly, The redder the granulations of wounds, the more healthy is
their nature; the paler or browner they are, the less has the part
a tendency to cicatrise.
6thly, The lively colour of the face, and the ardent eye, coincide
with the energy of the cerebral actions in certain fevers.
7thly, The more developed the pulmonary system of animals, the
more active are the chemical processes of the lungs, and the more
developed and perfect the general life of their different organs.
8thly, Youth, which is the age of vigour, is that also when the
red blood predominates in the system. The arteries of old people
are smaller, the veins larger than those of the young. It is a
fact universally known, that at the two extremities of life the
proportions of the two vascular systems are inverted.
I am ignorant of the manner in which the red blood excites and
keeps up the life of the parts. Perhaps the principles by which it
is coloured become combined with the different organs to which it
is distributed. In fact there is a considerable difference between
the phenomena of the general and those of the capillary system.
In the first, the blood in changing its colour, leaves behind it
the principles which made it red; in the second, the elements to
which its blackness is owing, are rejected by respiration and
exhalation. Now, this union of the colouring principles of the
arterial blood, may probably constitute a material part of the
excitement which is necessary to the action of the organs.--If
such be the case, the black blood as it does not contain the
materials of such union, cannot act as an exciting cause. This
idea, however, I offer only as a probability, and am by no means
prepared to defend it as a truth; it may be ranked on a par with
that of the sedative action, which I have said may be excited by
the black blood on the different parts--for, however probable an
opinion may appear, there should be no real importance attached to
it as an opinion only.
Without regard then to any system, let us inquire how the black
blood, from its contact with the various parts, is the occasion of
their death; how it acts on the parts of the animal life, and how
it acts on those of the organic life.
All the organs of the animal life depend upon the brain; now, we
have seen that the black blood paralyses the cerebral powers almost
suddenly. In the state then of asphyxia, the locomotive, the vocal
and sensitive organs, must be inactive. From the same cause, their
exercise must be suspended in all those different experiments where
black blood is injected into the brain, the other parts receiving
the red blood as usual. But when the black blood circulates
throughout all the system, when the whole of the organs, as well as
the brain, are submitted to its influence, then there are two other
causes of death connected with those which have been mentioned.
1st, The nerves, which are penetrated by it, for that very reason
are no longer capable of keeping up the communication between the
brain and the senses on the one hand, and on the other, between
this same viscus and the locomotive or vocal organs.
2dly, The contact of the black blood with these organs themselves
annihilates their actions. Inject the crural artery of an animal
with the black blood taken from one of its veins, and the movements
of that member will be shortly afterwards enfeebled, or wholly
paralyzed. In this experiment, the upper part of the artery, for
manifest reasons, should be that to which the pipe of the syringe
should be fixed.
I am aware that as to this experiment, it may be asserted that the
ligature of the artery, of itself, is capable of paralyzing the
limb. In fact, such circumstance has happened twice with me, but
I have also had occasion to observe, that it does not necessarily
follow the ligature of this vessel, as it does the ligature of
the aorta: when the latter vessel is tied, all movements cease at
once; notwithstanding all which, the result of the injection of
black blood, is almost constantly that which I have asserted it to
be;--I say almost, 1st, Because I have once seen it fail in its
effect, though done with the requisite precautions; 2dly, Because
the debility, which is induced, both in duration and degree, will
be according to the strength of the animal on which the experiment
is made.
There is also occasioned in this experiment, a manifest suspension
of the sensibility of the animal; it is not indeed so ready to
appear as the loss of motion; but it always comes on, especially if
the injection of the black blood be repeated three or four times,
with small intervals.
A similar, but a more tardy effect may be produced by adapting
to the canula, which has been placed in the crural artery of an
animal, a tube which has been previously fixed to the carotid
of another animal, and then by asphyxiating the latter.[96] The
organs of the internal life are not dependent on the brain, and
therefore are not affected by the suspension of the cerebral action
in asphyxia. It is the influx of the black blood which is the
immediate cause of their death.
I have already demonstrated what the influence is of this blood
upon the organs of the circulation. We have seen how the heart
ceases to act, as soon as it is penetrated by it; it is owing
in part to the injection of the arterial and venous parietes
themselves, by the vasa vasorum, that the vessels are forced to
suspend their actions.
It will be always a difficult thing to prove, that the secretions,
the exhalations, and the process of nutrition, could not be made
from venous blood, because the circulation of this sort of blood
in the arteries, does not continue for a sufficient time, to allow
of observations, or the manner in which these functions would be
affected by it. On this subject, however, I have made some essays.
1st, I exposed the inner surface of the bladder of a living animal,
after having previously divided the symphysis pubis, and opened
the lower belly, I then examined the oozing of the urine from the
orifices of the ureters, while I asphyxiated the animal. 2dly, I
divided the vas deferens, with the view of observing, whether the
semen would flow or not, during such state.
In general, I have had occasion to remark, that during the
circulation of the black blood in the arteries, no fluids appear
to issue from the different secreting tubes. But I confess, that
in all these experiments, and in other similar ones which I have
made, the animal is too much agitated, and the limits of the
experiments too circumscribed, for any thing like a well founded
judgment to be formed on the subject in question. It is chiefly
from analogy, then, that I am led to conclude, that the black
blood is unfit for the purposes of exhalation and nutrition:
such supposition also accords well with divers of the phenomena
of asphyxia.--1st, The want of exhalation from the skin during
the state of asphyxia, is probably the reason of the phenomena of
the animal heat in such sort of death.[97] 2dly, In asphyxiating
animals very slowly during digestion, I have uniformly observed,
that the bile ducts, and duodenum, contain a much less quantity
of bile, than they do at such time, when these parts are exposed
in the living animal.--3dly, As the blood loses nothing from the
exercise of these functions, it must of course accumulate in the
vessels; and in fact, it is very fatiguing and unsatisfactory, to
dissect the bodies of those who have been hanged or asphyxiated
with the vapours of charcoal, from the fluidity and abundance of
their blood. But this abundance, perhaps, may depend upon the
weakness of the absorbents. In other sorts of death, the absorbents
continue for some time to act upon the serous portion of the blood
remaining in the vessels. In asphyxia there is neither secretion
nor absorption.
The excretions also appear to be affected much in the same way.
The bladder of asphyxiated persons has been observed by Portal, to
be very much distended. Such distension, no doubt is occasioned
by the urine already secreted before the accident which was
the cause of their deaths. In general, the asphyxiæ which are
occasioned by the circulation of the black blood unmixed with any
deleterious substance, are not accompanied with those spasms, which
in so many other sorts of death, are so frequent. These spasms,
which evacuate the organs of their fluids, should be carefully
distinguished from the simple relaxations of the sphincters, by
which analogous effects are produced.[98] In asphyxia, all is
debility, in asphyxia, we never see that augmentation of life, that
development of power, which so frequently mark the latter movements
of the dying.
Hence also perhaps, the great flexibility of the members of
asphyxiated persons. The stiffness of the muscles appears to
depend in many cases, on the circumstance of death having come on
precisely at the moment of their contractions. The fibres remain
approximated, and coherent among themselves;[99] in asphyxia, on
the contrary, as there exists an universal relaxation and want
of action in the parts, they remain so after death, and yield to
whatever impulse may be communicated to them.
I confess, however, that this explanation is subject to a
difficulty which I cannot solve. Persons asphyxiated by mephetic
vapours, perish nearly in the same way as those who are drowned; if
the cause of their death be different, its effects are the same,
as may be seen by opening the carotid of two dogs at the same
time, that into the lungs of the one are injected the vapours of
charcoal, and into those of the other, a certain quantity of water,
which water, as in the drowned, is soon reduced into a state of
foam.
Notwithstanding this similitude of the last phenomena of life in
the two cases, the members in the first remain for a certain time
warm and supple, while those in the second, especially if the body
be plunged into water during the experiment, become very suddenly
stiff and frozen. Let us return, however, to our subject. We may
conclude from the various facts and considerations related in this
chapter, 1st, That when the chemical functions of the lungs are
suspended, the functions of all the other organs are suspended
also, from the presence of black blood within their substance.
2dly, That the death of the organs in general, coincides with that
of the brain, and the heart, but is not immediately derived from
them. 3dly, That if it were possible for the brain and heart to
receive an influx of arterial blood, while the others were dying,
from that of the venous blood, they would doubtless continue to
exert their accustomed actions. 4thly, That, in a word, asphyxia is
a general phenomenon, developed at the same time in all the organs,
but especially in one of them.
From this manner of regarding the influence of the black blood upon
the different parts of the body, it appears that death is very
soon the result of its circulation in the arteries. Nevertheless,
certain organic defects have sometimes prolonged after birth, the
mixture of the two sorts of blood, a mixture which is known to
be made in the fœtus. Such was the malconformation mentioned by
Sandeford, in a child, the aorta of which arose by a branch from
each of the ventricles. Such also appears, at first sight, to be
the opening of the foramen ovale in the adult.
We shall remark, however, that the existence of this foramen, does
not suppose the passage of the black blood into the red-blooded
auricle, as is generally believed. For the two semi-lunar
valves, between which it is situated when met with after birth,
are necessarily applied to each other by the pressure which the
blood contained in the auricles, exercises upon them, when these
cavities are simultaneously contracted. The foramen must be at such
time shut, and its obliteration much more exact, than that of the
opening of the ventricles, by the mitral and tricuspid valves, or
that of the aorta and the pulmonary artery, by the sigmoid valves.
With all this, the foramen ovale is actually very often found open
in the subject, and when not so, nothing is easier than to destroy
the species of adhesion which is contracted by the two valves which
close it. This may be done with the handle of a scalpel, without
any solution of continuity, the parts appear to be unglued.
The oval hole when in this way artificially made, presents the
same disposition, with that which is sometimes exemplified in the
carcase. Now if this disposition be examined, it will be seen that
when the auricles contract, the blood must make an obstacle to
itself, and that it cannot pass from one into the other of these
cavities. It is an easy thing to be convinced of the mechanism of
which I speak, by means of two injections of a different colour,
made at the same time from both sides of the heart, from the vena
cava, and the pulmonary veins.
From what we have said of the influence, which is exercised by the
movement and the different principles of the blood, it is evident
that the death of the white organs must be different from that of
the red ones. Asphyxia can hardly reach them, but of the manner in
which they die I confess that I know but little.
FOOTNOTES:
[94] It is not possible to remove by this means a great portion
of air contained in the lungs, for the last ramifications of the
air-tubes being flexible, their parietes soon come in contact, and
thus oppose the exit of the air contained in the bronchial cells.
[95] These observations have been made on the great mammalia, and
there has not been remarked any difference of colour.
[96] The difference that is remarked in the results of this
experiment, compared with that in which the venous blood is
introduced by means of a syringe, arises probably from this, that
in the first the blood that is forced into the artery has already
begun to coagulate.
[97] The deficiency of cutaneous exhalation in the last moments of
life may contribute a little perhaps to the preservation of animal
heat; but we have shown that there are other more powerful causes
for this phenomenon. This deficiency of exhalation united to the
inaction of the secretory organs, in the very short period in which
the black blood runs in the arteries is an altogether insufficient
cause to explain the abundance of blood that is found in the
vessels of those who have died of asphyxia.
[98] This is not an uniform fact, and it is even very common to
find, in persons who have been hung, the bladder completely empty.
[99] The moment respiration ceases, and the source of heat is
consequently cut off, it is not astonishing that an animal body
should become cold quicker in water then in a much less dense
fluid, like the air. It should also be remarked that the water, on
account of the evaporation that takes place on its surface, has
almost always a temperature below that of the surrounding air.
CHAPTER IX.
OF THE INFLUENCE OF THE DEATH OF THE LUNGS, OVER THE GENERAL DEATH
OF THE BODY.
In recapitulating what has been said in the preceding chapters,
with respect to the influence of the lungs over the heart, the
brain, and all the organs, it is an easy matter to form an idea
of the successive termination of the whole of the functions, when
the phenomena of respiration are suspended either mechanically or
chemically.
The following is the manner in which death supervenes, when the
mechanical phenomena of the lungs are interrupted, either from the
causes mentioned in the 5th chapter, or from similar ones, such as
the rupture of the diaphragm, which I have twice had occasion to
observe,[100] or from a fracture of a great number of the ribs, or
the sternum.
1st. The mechanical functions of the lungs cease. 2dly. The
chemical functions of the lungs cease also. 3dly. The cerebral
actions are put an end to. 4thly. The animal life is interrupted.
5thly. The general circulation is interrupted. 6thly. The capillary
circulation is interrupted.
The phenomena of death, are differently concatenated, when they
begin by the suspension of the chemical functions of the lungs:
which may happen, 1st, From breathing in a vacuum; 2dly, From the
obliteration of the passage of the trachea, by foreign substances
introduced into it, or by tumour from without, or strangulation,
accumulation of fluid in the air cells, &c.; 3dly, From different
inflammatory affections, schirrhi, &c. of the cavities of the mouth
or throat. 5thly, From want of respirable air, as on the summit of
high mountains. 6thly, From the introduction into the air cells of
non-respirable gases, &c. &c. In all these cases, the following is
the order of the phenomena of death.
1st. The chemical functions of the lungs are suspended. 2dly.
The functions of the brain are interrupted. 3dly. Sensation,
locomotion, the voice, the mechanical phenomena of respiration
cease. 4thly. The action of the heart, together with the general
circulation is annihilated. 5thly. The capillary circulation is put
an end to, together with the processes of secretion, exhalation,
absorption, and digestion. 6thly. The animal heat of the system
dies away.
I. _Remarks upon the differences of asphyxiæ._
The influence of the black blood as I have said, is always the
great agent in this double sort of death, but it is not the only
one: if that were the case, the phenomena of all the asphyxiæ would
be alike. It is true that in every sort of asphyxia, the black
blood ceases to become red blood, and circulates in the arteries,
such as it is in the veins; but notwithstanding the uniformity
of this phenomenon, there can be nothing more varied, than the
symptoms and progress of these accidents. In some of them, death
is long in taking place; in others, almost instantaneous: the
phenomena developed in the last moments of existence, are alike in
none of them. The state of the organs, and that of the powers which
they preserve after death, are as various.
1st, Asphyxia varies with respect to its duration; in sulphurated
hydrogenous gas, in nitrous gas, and certain vapours arising from
privies and sewers, it is quick in taking place. In carbonic acid
gas, azote, in pure hydrogen, water, and a vacuum, its progress is
slower.
2dly, Asphyxia varies with respect to its attendant phenomena. At
times, the animal is violently agitated and suddenly convulsed; at
others, it appears to lose its powers gradually; to pass into a
state of sleep, and from sleep into a state of death. In comparing
the numerous effects arising from the vapours of sewers, from those
of charcoal, from the different gases, from drowning, and other
causes of asphyxia, we find them almost as various, as the causes
themselves.
3dly, The phenomena which make their appearance after death, are
as variable. Compare the cold and frozen carcase of a drowned man,
with the remains of one who has been suffocated. Read the result
of the different experiments of the Institute, upon the affections
of the galvanic fluid in the different asphyxiæ; examine Halle’s
detail of the symptoms which accompany the mephitism of sewers;
approximate the numerous observations, which are scattered about
in the works of Portal, Louis, Haller, Troja, Pechlin, Bartholin,
and Morgagni; repeat the most common experiments on the submersion,
strangulation, and suffocation of animals; and you will observe the
greatest difference in all these sorts of asphyxia, they are each
of them characterized, by a peculiar state of the bodies of the
animals, which have been submitted to the experiment.
To inquire into the causes of such differences, we must first
divide the asphyxiæ into two classes. 1st, Into those which happen
from the simple want of respirable air, and 2dly, Into those, where
to this first cause is joined also that of the introduction of some
deleterious substance into the lungs.
In the first class, the immediate cause of death, appears to be the
simple presence of the black blood, in the various parts of the
body, the general effect of which is always the same, in whatever
manner produced; accordingly, the attendant symptoms and secondary
results of all these sorts of death, are nearly alike, their
duration the same, and if it varies, it varies only in consequence
of the more or less complete interruption of the passage of air
into the lungs.
This variety in the duration and intensity of the asphyxiating
cause, may nevertheless occasion some variety in the symptoms also;
such as a greater or less lividity and swelling of the face, a more
or less considerable embarrassment of the lungs; but all these
differences indicate only so many modifications of the cause, 1st,
A man who is hanged, does not die as a man who is suffocated by
an inflammatory tumour, or a pea or bean which perchance may have
fallen into the trachea.[102] 2dly, An animal will perish much more
slowly under a vessel of air, than when the trachea is tied. 3dly,
The symptoms of asphyxia, when occasioned by a great rarefaction of
air, or by a suffocating heat, are much less slowly produced, than
where the cavity of the lungs is opened.
In all these cases the cause of death, namely the absence of red
blood in the arterial system, is simple and unique, but according
to the greater or less oxygenation of the venous blood, will be the
appearances after death, for the longer the process of asphyxia
endures, the less irritability will there be found in the system.
But if the cause of asphyxia, have been the introduction of some
deleterious fluid into the lungs, then the variety of the symptoms
will depend upon the difference in the nature of the fluid. In
these cases the cause is of two kinds: 1st, There is no red blood
in the system. 2dly, A pernicious fluid is present in the system.
All the gases however do not act as deleterious substances: in pure
hydrogen for instance, the animal perishes only as it would from
the want of respirable air.
But when a man in descending into a common sewer, into a cellar,
or into any place where putrid matters are accumulated, falls into
asphyxia at the moment when he inspires their exhalations, and
when such state is attended with convulsive movements and extreme
agitation, then indeed, there must be something more in the cause
of his death, than a simple suspension of the chemical functions of
the lungs.
In fact, together with the mephitic vapour, there continues to
enter into the lungs a sufficient quantity of air to keep up
life and its different functions. 2dly, Supposing even that the
quantity of mephitic air were such as to leave no place for the
entrance of respirable air, still the death ensuing should only be
gradual, without agitation and convulsion, were it occasioned only
by the absence of such air: now the very different way in which it
supervenes, very evidently indicates the action of a deleterious
substance, upon the animal œconomy.[103]
These two causes then act together, in those asphyxiæ which
are produced by certain gases, sometimes the one predominates,
sometimes the other. If the deleterious substance be violent, it
kills before the action of the black blood can have produced much
effect, if weak, it is the black blood, which is principally the
cause of death.
The asphyxiæ then, which are produced by the gases, differ only,
in consequence of the nature of the deleterious substance, which
varies ad infinitum. In some of the aeriform fluids indeed it
is supposed to be known, but in the greater number of them it
is not so:[104] I shall notice therefore in a general way the
effects, which result from the action of the deleterious substance,
remarking at the same time, that the symptoms by which they are
displayed, are strongly or weakly marked, according to the age and
temperament of the individual.
Deleterious substances introduced into the lungs, together with the
mephitic vapours of which they form a part, can act only in two
ways. 1st, By affecting the nerves of the lungs, which re-act on
the brain. 2dly, By passing into the blood, and exercising their
influence, by means of the circulation on the various organs of the
system.
I can easily believe that the simple action of such a substance
on the nerves of the lungs, may have a very marked effect on
the economy, and be capable of troubling the functions of the
system very sensibly; much indeed in the same way as with some
individuals a mere odour, or the sight of a hideous object, will
occasion syncope, in the same way that an irritating enema will
suddenly awake the system into life, or the introduction of
certain substances within the stomach, will be felt throughout the
body, before such substances can have passed into the circulatory
torrent. We meet at every moment with examples of these very
remarkable phenomena, produced by the simple impressions of foreign
bodies on the mucous surfaces; I cannot deny that deleterious
substances may act in the same way upon the nerves of the
lungs, though we must not exaggerate the sphere of this mode of
action.[105]
In fact, I am not acquainted with any one example, where the
contact of a deleterious substance with a mucous membrane, has been
the sudden cause of death. It may indeed be productive of such
effect after a certain time, but never at the moment of its action;
nevertheless, in those asphyxiæ which are produced by mephitic
vapour, so rapidly does death come on, that the black blood can
scarcely have had the time to exert its influence upon the body.
The principal cause of the cessation of the functions is manifestly
the action of the pernicious substance.
These considerations, then, incline me to believe, that these
substances pass into the blood through the lungs, and that in
circulating with the blood they carry to the organs the immediate
cause of their death. Such passage into the blood has already been
suspected by many physicians; the truth of the fact appears to be
indubitably proved by the following reflections.
1st, It can hardly be doubted, that the poison of the viper and
many other venomous animals, and that the saliva of rabid animals,
pass into the system of the blood, and are taken up either by the
veins or the lymphatics.
2dly, It appears to be very certain, that a portion of the
atmospheric air is actually absorbed through the mucous membrane of
the lungs itself, and not by means of the absorbent system. Now,
if this be the case, I know not what should hinder the passage
of mephitic vapour in the same way.[106] We are not sufficiently
acquainted with the limits of the particular sensibility of the
membrane of the air cells, to say that it cannot give a passage to
such vapour.
3dly, The respiration of an air which has been charged with
the exhalations arising from oil of turpentine, communicate a
particular smell to the urine. It is thus that this fluid is
affected from the residence of the persons in a newly varnished
room. In this case it is evidently by the lungs in part, that the
odoriferous fluid has its passage into the blood, and so on to the
kidneys. In fact, I have often assured myself by breathing out of a
bottle through a tube, air so charged (in which case it could not
act on the cutaneous surface) that the smell of the urine undergoes
a change. If, then, the lungs will admit a variety of substances,
which do not enter into the composition of respirable air, for
what reason should they not admit the mephitic vapour of mines and
subterraneous places.
4thly, The respiration of humid air produces dropsy. The extent
of the fact has been exaggerated, indeed, but the fact itself is
true. It proves, that an aqueous fluid may pass into the blood, and
consequently that other substances may pass into it also.
5thly, If an animal be asphyxiated in sulphurated hydrogenous gas,
and a plate of metal some time after its death be placed under
one of its muscles, the surface of the plate contiguous to the
muscle, will be sensibly sulphurated. The foreign principle, then,
which is here united with the hydrogen, must have been introduced
into the circulatory torrent by the lungs, and have penetrated
with the blood into all the parts. The deputies of the Institute
have observed this phenomenon in their experiments. I have made
a similar remark in asphyxiating animals with nitrous gas. A
phenomenon of the same nature accompanies the exhibition of mercury.
From the above, we have nearly a right to conclude, that the
different deleterious substances of which the gases are the
vehicles, do actually pass into the blood, and so affect the
organs. Of this matter, however, I shall adduce some further
proofs.
I have ascertained by a number of experiments, that atmospheric
air, or any other aeriform fluid, may be made to pass into the
blood without alteration.
Divide the trachea of a dog, inject the air-cells strongly with
common air, and continue to retain it in the lungs. The animal will
immediately discover signs of great distress and agitation; if an
artery now be opened, the blood will be emitted in a frothy state.
If hydrogen have been employed, it may easily be ascertained that
the nature of the fluid is unchanged, by placing a candle over the
bubbles which are disengaged.
When the blood for the space of thirty seconds has flowed in this
state, the animal life of the creature will be finished, and death
ensue, with all the symptoms which accompany the insufflation of
air into the black-blooded system of vessels. The re-admission of
air into the lungs, will have no effect in restoring the animal
to life, for as soon as frothy blood can flow from any one of
the arteries, it must already have affected the brain with its
pernicious influence.
In this case it may be perceived, that the causes of death are the
same as those which proceed from the insufflation of air into a
vein. In the one instance the air passes at once from the lungs
into the arterial system. In the other, from the veins across the
lungs and then into the arteries.
When we open the bodies of animals, which have been killed in
these experiments, the whole apparatus of the red-blooded vascular
system, is found to be filled with air bubbles of various sizes. In
some circumstances, the blood will be transmitted in the same state
into the general capillary system, and from thence into the veins;
in others it will be stopped in the capillary system, and in such
cases, though the circulation may have continued for some time
after the suspension of the animal life, not a single particle of
air will be discovered in the veins.
In these experiments which I have frequently repeated, I have
never found that the least fissure has been made in the bronchiæ;
nevertheless, I confess that it is difficult to say, whether this
be so in their last ramifications. The following phenomenon,
however, may throw some light upon the subject; for as often as
air is pushed into the lungs with great violence, there will be
produced an emphysema of the breast, or neck, from the infiltration
of this fluid among the cellular texture, in addition to its
passage into the blood. But if the impulse be moderate, and the
quantity of air injected not much beyond the measure of a full
inspiration, it will pass into the blood only, and not into the
cellular texture.[107]
The experiments of which I have given the detail, exemplify
phenomena which do not indeed take place in the ordinary process
of inspiration, and therefore I allow that no very rigorous
induction can be drawn from them, with respect to the passage of
deleterious substances into the mass of the blood; nevertheless
it appears to me, that they very much confirm the probability of
such fact, which besides is demonstrated by many of the preceding
remarks. I shall conclude, then, that such passage is real. In
fact, we have seen 1st, That the sole transmission of the black
blood into the arteries, will not account for the infinitely
various phenomena exemplified in the different sorts of asphyxiæ;
2dly, That the simple contact of the deleterious substance with
the nerves of the lungs, can by no means be the cause of a death
so rapid as that which is occasioned by these accidents; 3dly,
That, therefore, we are forced as it were to suspect the passage
of the poison itself into the blood; 4thly, That a number of
considerations are in favour of such suspicion, and thus that the
fact is proved both directly and indirectly.[109]
This principle being once established, a variety of results must
flow from it. Of the first of these, of the mode of action, namely,
which the deleterious substance must exercise upon the different
organs, I shall say nothing, having nothing to offer but conjecture.
I shall accordingly content myself with inquiring what system it
is which is particularly influenced by these substances, when
mingled with the blood.--Now, 1st, This system appears to be the
nervous one, and that portion of it especially, which presides over
the parts of the animal life, the organic functions being only
secondarily affected; 2dly, Of all the nervous system, the brain
is that part which is the most affected; 3dly, Under this relation
Monsieur Pinel appears to me to have been right, in placing some
of the asphyxiæ (those for instance which are occasioned by the
presence of a deleterious substance) among the neuroses. On this
head the following considerations should leave us little doubt.
1st, In all the asphyxiæ, when the presence of a deleterious
substance cannot be doubted, the symptoms consist of two general
and opposite sets of phenomena, of spasm and torpor. Of two workmen
who had come up out of the sewer of the street St. André des Ares,
the one sat himself down upon a bulk, and fell into a state of
asphyxia; the other with irregular convulsive movements, proceeded
as far as the rue Battoir, and then fell down asphyxiated. The
Sieur Verville, in consequence of inhaling the breath of a man
who was lying in a state of asphyxia from the vapour of lead,
fell down suddenly, and in a short time became convulsed. The
vapour of charcoal intoxicates, as it is said. I have seen animals
asphyxiated with other gases, and perishing with a stiffness, such
as could be produced only by the most violent spasm. The centre
of all these symptoms, and the organ from which they emanate,
undoubtedly is the brain, and they depend upon its irritation or
compression.
2dly, The animal life is always interrupted before the organic
life, wherever the asphyxiating cause has been of a compound
nature. Now the centre of the animal life is the brain.
3dly, I have proved when the animal perishes from the circulation
of the black blood in the arteries, that the brain is especially
affected even then; but in the same way, that is, by the cephalic
arteries, the deleterious substance itself, may be introduced into
the brain.
4thly, I have pushed a variety of deleterious gases (for example,
sulphurated hydrogen) into the brain, and also some of those
substances which vitiate the nature of these gases. The animal has
always perished with symptoms of spasm, or torpor, and in general
the death which is occasioned by the different gases, is always
similar to that which is produced by the introduction of pernicious
substances into the brain.
5thly, The consequences of these asphyxiæ, when life has been
restored, invariably suppose a lesion of the cerebral system,
such consequences consist of palsy, tremour, wandering pains, and
derangements of the exterior apparatus of the senses.
From all these multiform experiments and considerations, we may
surely conclude, that it is on the brain and nervous system that
the deleterious principle, introduced into the blood, must act;
from the death of these parts, that of the others is derived.
In this case the different organs no doubt are directly enfeebled,
and may perhaps be immediately affected by those principles, which
flow into them together with the blood, but all such phenomena, are
even more visible in the animal, than in the organic life.
Let us not forget however, that a part at least of the cause of
this sort of death, consists in the influence of the venous blood
upon the organs, and that this influence must ever be in proportion
to the length of time that such blood continues to circulate. The
differences then which are found in the asphyxiæ, may be said to
proceed from the greater or less effect of the venous blood upon
the system, from the different nature of the various deleterious
substances inspired, and from the age and temperament of the
individual affected.
II. _In the greater number of diseases, death commences in the
lungs._
I have just spoken of sudden death. I shall now enlarge a little
on that which is the slow effect of disease. Physicians must be
well persuaded, that by far the greater number of diseases, put
an end to life by an affection of the lungs. Whatever be the seat
of the principal affection, be it either an organic lesion, or a
general disorder of the system, the action of the lungs in the
latter moments of existence, becomes embarrassed, the respiration
difficult, and the oxydation of the blood, but slowly effected;
accordingly this fluid must pass into the arteries, almost in the
venous state.
The organs therefore which are already enfeebled, must be much more
readily affected by the pernicious influence of such blood, than
those which are subject to it, in the different cases of asphyxia.
In this way the loss of sensation, and intellect, are very shortly
the effect of embarrassment in the lungs; and ensue as soon as
the brain begins to be penetrated with the fluid which is so
transmitted to it.
By degrees the heart and all the organs of the internal life,
cease also to move. It is here the black blood which arrests these
vital motions, which have already been enfeebled by the disease.
Such weakness, the consequences of the disease, is very rarely the
immediate cause of death, it only prepares it, by rendering the
organs more susceptible of the alteration in the healthy state of
the blood. Such alteration is almost always the immediate cause
of death. The disease then, is only an indirect cause of death in
general, it kills the lungs, and the death of the lungs occasions
that of all the other parts.
From hence it may be easily conceived, why the small quantity of
blood contained in the arterial system of the subject, is almost
always black. For 1st, The greater number of deaths begin by the
lungs. 2dly, We shall see that those which have their commencement
in the brain, are equally the cause of this phenomenon. Accordingly
there can be only those, in which the heart ceases suddenly to act,
after which the red blood can be found in the aortic ventricle, and
auricle. Such appearance is seldom found, excepting in the bodies
of persons who have perished from extensive hemorrhagy.
From the frequency of deaths beginning with an embarrassment of
the lungs, may be conceived also the reason, why this organ is so
frequently gorged with blood in the carcase in general, the longer
the agony, the heavier and fuller are the lungs. When such fulness
is found, together with black blood in the red-blooded system,
whatever the disease may have been, it may be pronounced that death
has begun in the lungs. In fact the concatenation of the phenomena
of death is from one of the three organs, from the lungs, brain,
or heart, to all the others. Now when death begins in the heart,
the pulmonary vessels are generally empty, and there is red blood
in the aortic system. On the other hand, if death has begun in the
brain, there is then indeed a certain quantity of blood in the
arteries, but the lungs are empty, unless, when gorged with blood,
by some antecedent affection.
FOOTNOTES:
[100] When the diaphragm is ruptured, a sudden cessation of the
functions is not always the result of this accident. Patients have
been known to survive many days, and the cause of death has only
been ascertained by examining the body.
The intercostal muscles are, in this case, the sole agents of
respiration, which becomes nearly analogous to that of birds or to
that of animals with red and cold blood, who are destitute of the
septum between the thorax and abdomen.[101]
Lieutaud cites various ruptures of the diaphragm, produced by other
causes than external injuries. Diemerbroech has seen this muscle
wanting in an infant who still lived to the age of seven years.
[101] When from any cause, the diaphragm cannot contract, the
enlargement of the thorax is effected solely by the elevation of
the ribs, and as this motion is then very evident, we can then
appreciate better the influence the intercostal muscles have in
its production in ordinary respiration. Haller, as is well known,
supposed that the first rib was almost immoveable, and that the
muscles in the first intercostal space, took it as their fixed
point to elevate the second. This second rib, in its turn, served
as a fixed point to elevate the third, and thus on to the last rib.
But if we observe the mechanical phenomena of respiration when
the diaphragm does not contract, as is the case in diaphragmatic
pleurisy, we see that the first rib is far from being immoveable.
Now, we cannot conceive how the intercostals which are attached
to its inferior part, can, by contracting, assist in raising it.
Besides, in order to elevate the ribs, a very great resistance must
be overcome, and the intercostal muscles are too slender to induce
us to suppose that they are capable of effecting it. The principal
agents of this motion then are the anterior and posterior scaleni,
which are distinctly seen to contract in great inspirations, the
supra-costales and the muscles of the neck which attach it to the
sternum. We ought to add to these a muscle, to which this use has
never before been attributed; I mean the diaphragm. This muscle in
fact in its contraction tends to become flat, from being concave
as it is in inspiration. Now, its middle part in depressing the
abdominal viscera experiences a certain resistance, and takes, as
it were, from them a fixed point, by means of which it elevates the
base of the thorax to which its circumference is attached.
[102] Asphyxia is not always the cause of death in those who are
hung, there is sometimes connected with it a more efficient cause,
which consists in the compression of the spinal marrow. This was
formerly very often observed in those who had been executed,
because the executioner in throwing them off gave a rotatory motion
to the body which produced the luxation of the first vertebra on
the second.
[103] By injecting into the veins different irrespirable gases,
Nysten has been able to distinguish the effects which result from
the deleterious properties of the gases from those which arise from
the alteration of respiration from a want of atmospheric air.
Thus among the elastic fluids which he tried, he found sulphuretted
hydrogen, the deutoxide of azote, chlorine and ammoniacal gas
eminently deleterious; for introduced in sufficient quantity into
the animal economy they uniformly cause death, whilst others,
such as oxygen, azote, hydrogen, carburetted hydrogen, carbonic
acid, oxide of carbon, and protoxide of azote do not produce death
when introduced into the lungs, except by excluding the only
mixture, that can support respiration; in no other way do they
occasion death, at least in a sudden manner. If however, they
are thrown quickly into the blood vessels, they cause death, but
it is mechanically and in the same way as atmospheric air would
do it. It should also be observed that these different gases do
not all act in the same way when they are introduced into the
lungs; the gaseous oxide of carbon destroys animals much quicker
than azote or the protoxide of azote. They die also quicker in
the proto-phosphuretted hydrogen, and even in the carbonic acid
gas. There are also in the action of deleterious gases certain
anomalies which have not hitherto been explained. Nysten injected,
at three injections, into the veins of a dog of middle size thirty
centimetres of sulphuretted hydrogen. The animal after the first
injection, was agitated, and made powerful inspirations; the second
produced convulsive motions and the third apparent death; but the
next day he was entirely well. Now a less quantity of sulphuretted
hydrogen carried into the organs of respiration and mixed with five
or six hundred times its volume of air, would infallibly destroy
the animal.
[104] The composition of some of these vapours is better known
at the present day; but there are others in which our means of
analysis have been unable to detect the deleterious principle;
thus in the _malaria_, which has depopulated the country in the
neighbourhood of Rome, our chemists have as yet only found as
constant elements, those which enter into the composition of
atmospheric air.
[105] It appears from the experiments of M. Desormes that the
contact of sulphuretted hydrogen on the skin of an animal is
immediately fatal.
[106] We know that fine injections pass from the branches of the
pulmonary artery into the divisions of the bronchia; and that even
water, when pushed into the trachea, will return, at least a small
quantity of it, by the pulmonary veins and arteries.
Bichat thought that the gases absorbed in the lungs must pass
through the mucous membrane; but this is not the case unless
absorption takes place at the time they are in the bronchia, for
the mucous membrane which lines the air-tubes does not extend into
each bronchial lobule.
[107] This fact, frequently confirmed in my experiments, is not
always the same in man. We often see emphysema produced by violent
efforts of respiration, efforts which have forced into the cellular
organ the air contained in the lungs. Now, if the passage of the
air in the blood preceded or even accompanied its introduction
into the neighbouring cells of the bronchia, all these cases
of emphysema would be necessarily fatal, and even in a sudden
manner, since, from what has been said before, the contact of the
air on the brain, to which the circulation would carry it, would
inevitably interrupt the functions of this organ.
Yet we see that emphysema is often cured, or does not produce
death for a length of time.[108] I saw, at the Hotel Dieu, an air
tumour, suddenly appear in the axilla, from the violent efforts
of the patient to prevent respiration, whilst Desault reduced
an old luxation. In a few days this tumour disappeared without
producing any inconvenience. We find, in the Memoirs of the Academy
of Surgery and in Treatises on Operations, various examples of
emphysema produced by powerful agitations of the thorax, and
in consequence of the introduction of a foreign body into the
wind-pipe; emphysema, with which the patients have lived many days,
and from which even they have recovered.
There is then no doubt, that often in man the air passes from the
lungs into the cellular texture, without entering the arterial
system. My experiments on animals have not been exactly analogous
to what happens from the introduction of a foreign body, when a
part of the air enters and goes out. It is then probable that from
a cause precisely similar would arise also the same effect in
animals.
And vice versa, the passage of the air in the blood-vessels
sometimes takes place in man, without the infiltration of the
cellular organ; then the death is sudden.
A fisherman, subject to colick, was suddenly seized with it in his
boat; the abdomen swelled, the respiration became painful and the
patient died almost instantaneously. Morgagni opened the body the
next day, and found the vessels full of air. Pechlin also says
he saw a man die suddenly in great distress and with a hurried
respiration, and he afterwards found a large quantity of air in the
heart and in the large vessels.
I have dissected many bodies, in which, before death there had
been a sanguineous congestion in the exterior capillary system of
the face, the neck and even of the thorax. This system exhibited a
remarkable engorgement and lividity in all its parts, and I have
found in opening the arteries and veins, in those of the neck and
head especially, a frothy blood, mixed with bubbles of air. I
learnt that one of these subjects died suddenly with a convulsive
affection of the pectoral muscles; I have no information respecting
the others. Besides, all who have had much to do with dissecting
rooms, must have seen bodies of this kind, which very soon become
putrid and emit an insupportable odour. They have observed also
that the air in the vessels existed previous to the putrefaction.
I suspect that in all these cases death has been produced by the
sudden passage of air from the lungs into the blood, which has
afterwards carried it to the brain; nearly like what I have said
takes place, when, in a living animal, we force much air towards
the lungs, and thus drive this fluid into the vascular system.
By considering these phenomena in connexion with the remarks
presented above on death from the injection of air into the veins,
the opinion I have advanced, will I think, be admitted, and it is
besides the opinion of many other physicians. Many experiments
have already been made on the dead body relative to this point.
Morgagni has presented them in detail; but it is on the living that
we must observe the passage of the air into the blood in order to
deduce consequences which shall bear on the subject on which we are
treating. We know in fact what is the influence of death on the
permeability of the parts.
[108] I saw, in a little girl of seven or eight years of age, an
emphysema which occurred in a paroxysm of coughing, and which
extended to the thorax, the abdomen and the superior part of the
thighs; the swelling of the neck was so considerable, that at
the moment I was called suffocation was imminent. I made, in the
skin above the sternum, an opening, which very quickly produced
an evacuation of the air. In five or six days, though the hooping
cough continued, this little patient was entirely cured of the
emphysema, which had been very near destroying her. It did not
appear to me that the lungs had participated at all in the general
emphysema.
[109] The above experiments explain the manner in which emphysema
is produced from any very violent exertion of the muscles of the
chest.
CHAPTER X.
OF THE INFLUENCE OF THE DEATH OF THE BRAIN OVER THAT OF THE LUNGS.
As soon as the human brain ceases to act, the functions of
the lungs are suddenly interrupted; this phenomenon, which is
constantly observed in the red and warm-blooded animals, can happen
only in two ways. 1st, Because the action of the brain, is directly
necessary to that of the lungs, or 2dly, Because the latter
receives from the former, an indirect influence by means of the
intercostal muscles and diaphragm, an influence, which ceases with
the activity of the cerebral mass. Let us try to determine which of
these two modes is that of nature.
I. _Is it directly that the lungs cease to act upon the death of
the brain?_
I shall have proved that the death of the brain, is not immediately
the occasion of that of the lungs, if I can determine that there
is no immediate influence exercised by the first, upon the second
of these organs, now, this essential principle may be easily
demonstrated by experiment.
The brain can exercise an immediate influence on the lungs, only
by means of the par vagum or the great sympathetic nerve, the
only nerves, which according to the common opinion, establish
a communication between the two organs (an opinion however
which is erroneous, as the great sympathetic is only an agent of
communication between the organs and the ganglions of the system.)
Now 1st, The influence which is derived by the lungs from the par
vagum, is not actually necessary for them to act. The following
experiments will show the truth of this assertion.
1st, Irritate the par vagum on one or both sides, and the
respiration of the animal will be somewhat quickened; but such
appearance is no proof of an immediate influence, for any wound of
the neck, or any wound whatever, provided that it be the occasion
of considerable pain, will be the cause of a similar phenomenon.
2dly, Cut one of the nerves, and the respiration will be at once
affected, as when the nerve is irritated; but as soon as the pain
ceases, the embarrassment of the lungs will disappear; and at the
end of four and twenty hours, the phenomena of life be concatenated
with their accustomed regularity.
3dly, Divide these nerves on both sides. In this case the breathing
will be much more precipitated, and will not return to its ordinary
state, as in the preceding experiment; it continues laborious for
four or five days, and the animal perishes.[110]
From the two latter experiments it follows, that the par vagum is
indeed necessary to the phenomena of respiration, and that the
brain must exercise, of course, an influence over this function,
but at the same time, it may be seen, that without the immediate
influence of the brain, the lungs will continue in play, and
consequently that the interruption of such influence, as when
the brain is injured, will not be an immediate obstacle to the
continuation of the pulmonary actions.
The question whether the functions of the lungs are more
immediately connected with the influence derived from the
ganglions, may be decided by the following facts.
1st, If on the one and the other side of the neck, the nervous
thread be cut, which is usually regarded as the trunk of the great
sympathetic, there follows little or no alteration in the phenomena
of respiration.
2dly, If the par vagum and the great sympathetic be divided at the
same time on both sides of the neck, the animal will die after a
certain time, and much in the same way, as when only the par vagum
is divided.
3dly, When we divide the sympathetic nerve in the neck, we do
not deprive the lungs of the nerves which come from the first
thoracic ganglion; now these nerves may contribute to keep up the
action of the lungs, since, as I have said, each ganglion is a
nervous centre, capable of emitting its own peculiar irradiations,
independently of the other centres, with which it communicates.
But whether the nerves, which are derived from the first thoracic
ganglion, do really assist the functions of the lungs, I have not
been able to ascertain by experiments on the nerves themselves,
for such is the position of the first thoracic ganglion in most
animals, that it cannot be taken away without doing so much injury
to the parts as would kill the creature, or throw it into such
agitation, as wholly to confound the phenomena of which we are in
search, with those of a general distress and trouble. From analogy,
however, and from the destruction of other ganglions, by which
the internal organs are supplied, we should not have a right to
suppose that the lungs would cease to act, when the ganglion in
question is destroyed.
Besides, the following reasons appear to me to prove
unquestionably, the principle which I advance. If great lesions of
the brain have the effect of suddenly interrupting respiration,
because this organ can no longer influence the lungs by means
of the nerves, which come from the first thoracic ganglion, it
is evident that if all communication between the brain and this
ganglion be taken away, such influence must cease, and respiration
be suspended; but if we divide, as Cruikshanks has done, the
spinal marrow on a level with the last of the cervical vertebræ,
the animal will continue to live and breathe for a length of time,
notwithstanding the want of communication between the brain and
the lungs, by means of the first thoracic ganglion. From the above
experiments, we may conclude, that the brain does not exercise any
direct and actual influence over the lungs, and consequently that
other causes must be sought for, if we mean to account for that
sudden and instantaneous cessation of the functions of the latter
of these organs, when those of the former are suspended.
There exists, notwithstanding, a phenomenon which seems to cast
some doubt upon the conclusion which I have deduced, and in the
principle which it establishes. I speak of the sudden difficulty
of respiration, and that impeded circulation which are occasioned
by violent pain. This distress appears to indicate that the heart
and the lungs are dependent immediately upon the brain; for the
distress is in the brain, say the greater number of authors, and
the affection of the heart and lungs, a consequence of the reaction
of the brain; but here let it be remembered, that almost all pain
is made up, first of sensation, and secondly of some _emotion_,
_passion_ or _affection_.[111] Now as I have proved at length, in
the former part of this work, all passion and emotion have their
seat in the internal viscera, and thus it will appear, that the
trouble which in such case is felt in the heart and lungs, does not
depend upon the brain for its cause, but is the immediate effect
of the passion, or emotion, which accompanies the sensation. The
following considerations will bear me out in this conclusion.
1st, In many instances the dyspnœa and impeded circulation, precede
the pain. Examine the thorax, and place your hand upon the heart
of a man about to undergo an operation, and you will be easily
convinced of this truth.
2dly, There is sometimes a manifest disproportion between the
sensation of pain, and the distress which is experienced about the
heart, and in breathing. I have known the operation of cutting away
the prepuce immediately fatal. Now in this case, it surely could
not be pain which killed the man.
3dly, There are many persons who are capable of supporting
violent pain, with resolution. Place your hand upon the heart
of such persons, and no agitation whatever will be felt there.
Nevertheless, their perception of pain must be what it is in other
persons.
4thly, In the course of an operation, we are not to judge of the
patient’s state of mind, from his cries, or silence. This sign
is very deceitful; because a man may be sufficiently master of
himself to overpower the influence of his internal organs. We
must examine the heart and lungs; their functions, if I may allow
myself the expression, are the thermometer of the affections of
the mind. It is not without reason, that the actor who plays the
part of a courageous man, takes hold upon the hand of him whom
he wishes to set at ease, and lays it on his heart. The exterior
movements of the passions, are not a fair criterion of the inward
feelings of the individual, for these movements may be feigned as
well as real: feigned if they originate in the brain: real if they
have their sources in the heart;--in the first case voluntary, in
the second involuntary. Touch the pulse of the angry man, if you
wish to know whether he really is in anger. When I see a woman
weeping or convulsed at any distressing news, and find her pulse
in its natural state, I know what to judge of her affliction.--On
the contrary, if her grief be concentrated, but her heart beat
strongly, or her pulse have been suddenly depressed, I know that
she feigns a calm which she does not feel. To judge correctly,
we must always compare the external movement with the state of
the internal organs. There could be no deceit, were it possible
to distinguish the involuntary movements produced in a state of
passion, by the action of the heart upon the brain, and then by
the reaction of the brain upon the muscles, from the voluntary
movements which are occasioned by the simple action of the brain
upon the locomotive system.
However strong may be the pain which has been the occasion of the
dyspnœa, and impeded circulation, of which we have been speaking,
this dyspnœa and distress about the precordia, will cease, provided
only that the pain be continued. Nevertheless, if the reaction of
the brain were the real cause of the distress in question, the
contrary should be the case; for the continuation of the affection
of the brain, should continue also to cause its re-action. But here
the effect of habit is evident, though the pain subsists; the brain
indeed continues to be affected, but the internal organs cease to
be so. It may be easily perceived, that I am not here speaking
of those cases, where the action of the heart and lungs has been
deeply troubled by the effect of pain.
To the above considerations I might add many others, with the view
of proving, 1st, That although the brain be the seat of the pain,
it is not the source of those affections of the internal organs,
which are occasioned by such pain; 2dly, That these affections
depend upon an emotion, which is absolutely distinct from sensation
of whatever kind, both in its nature and effects.
II. _Is it indirectly that the lungs cease to act upon the death of
the brain?_
Since the death of the lungs, upon the cessation of the cerebral
action, is not direct, there must exist between the brain and the
lungs, some intermediate agents, the cessation of whose functions,
occasion the cessation of those of the lungs. These agents are the
diaphragm, and intercostal muscles; for they depend immediately
upon the brain by means of the nerves, which they receive from it,
and consequently become paralytic on the death of the brain; the
following experiments are a proof of the fact.[112]
1st, Cruikshanks divided the spinal marrow of a dog between the
last cervical, and the first dorsal vertebræ. The intercostal
muscles accordingly were immediately paralyzed, and the breathing
of the animal continued to be made by the diaphragm only, which
receives the phrenic nerve from a point above the section. In
this experiment, it is easy to judge of the strong action of the
diaphragm, by that of the abdominal muscles.
2dly, If the phrenic nerves only be divided, the diaphragm becomes
immoveable, and then the respiration of the animal is effected by
the intercostal muscles only.
3dly, After the two preceding experiments, the animal will live
for a considerable time, but if the phrenic nerves, and the spinal
marrow, towards the end of the neck, be divided at the same time,
or what comes to the same thing, if the spinal marrow be cut above
the origin of the phrenic nerves, then all communication between
the brain and the active agents of respiration is cut off, and
death follows of course.
4thly, I have frequently observed, that half an inch of difference
in the place where the spinal marrow is divided, produces such a
difference in its consequences, that in the one case the death is
sudden, and supervenes in the other only, after an interval of
fifteen or twenty hours. In dissecting the carcases of animals
killed in this manner, I have constantly observed that the
difference depended always upon the circumstance, of the phrenic
nerve being cut or not.
From these experiments then it is evident, that respiration
ceases on a sudden, and in the following manner, in all lesions
of that part of the nervous system, which is placed above the
origin of the phrenic nerves. 1st, There is an interruption
of action in the voluntary nerves, which are placed below the
point of lesion, and consequently in the phrenic and intercostal
nerves. 2dly, A paralysis of almost all the muscles of the animal
life, and particularly of the diaphragm and intercostal muscles.
3dly, A cessation of the mechanical phenomena of respiration.
4thly, A suspension of the chemical phenomena of respiration.
The interruption of all these movements, is as rapid as their
concatenation is prompt, in the natural order.
It is thus that those persons perish, who experience any great
lesion of the spinal marrow, between the brain and the origin of
the phrenic nerves. Physicians have been very much embarrassed,
in fixing with precision the spot, when a wound of the medulla
ceases to be mortal; from what I have advanced, the limit is easily
assigned.[113] From the same causes, concussion, and compression of
the brain, are also fatal.
We should observe notwithstanding, that these different causes of
death, may act with various degrees of intensity. If they act but
feebly, they affect the intellectual functions only, for these
functions are always the first to be altered, in all lesions of
the brain however small. If the lesion be greater, the affection
extends to the muscles of the limbs, and convulsion or palsy ensue.
Lastly, if the lesion be very great, the whole of the muscles of
the animal life, the intercostals and diaphragm, as well as the
others, are paralyzed, and death follows.
We now can reply to the question proposed at the beginning of this
section, and affirm that the death of the lungs is occasioned
indirectly, by the death of the brain.
It follows also, from the principles which are above established,
that respiration is a mixed function, a function placed as it were
between the two lives, to which it serves as a point of contact,
belonging to the animal life by its mechanical functions, and to
the organic life, by its chemical functions; and hence we have
the reason no doubt, why the existence of the lungs is as much
connected with that of the brain, as with that of the heart.
It may be observed in the series of animals, that in proportion
as the organization of the brain is straitened, a number of the
phenomena of respiration also are lost. In birds, and the mammalia,
this function as well as the brain, is much more developed than
it is in the classes of fish and reptiles. It is known, that the
nervous system of those animals which breathe by tracheæ, is less
perfect than in those which breathe by lungs; and that in those,
where there is no nervous system, that of respiration disappears
also.
In general, there is a reciprocal relation between the brain and
the lungs, especially in birds and the mammalia. The first of
these occasions the action of the second, by raising the ribs and
favouring the entrance of air into the bronchiæ; the second also
keeps up the activity of the first, by means of the red blood which
it sends thither.
It would be an interesting speculation to inquire into the relation
of the nervous system with that of respiration in the class of
insects, for as they receive the air by points, which open
externally, there seems to be no mechanical action in the process
of their breathing, and thus the function appears with them to
belong entirely to the organic life.
FOOTNOTES:
[110] The division of the nerves of the eighth pair in the
neck produces two kinds of effects, which should be carefully
distinguished; the one relates to the larynx and the other to
the lungs. Among the first, aphonia is one of the most striking
symptoms. We see a very good reason for this phenomenon, when we
recollect that the recurrent nerve is a branch of the eighth pair;
but besides the loss of voice, the division of the eighth pair
often produces such an approximation of the edges of the glottis
that the air cannot enter, and death immediately takes place.
Most usually, the approximation is not sufficient to prevent
entirely the entrance of the air into the thorax; but as the
glottis has lost its motions in relation with those of respiration,
this function is always performed in a more or less incomplete
manner.
When these observations were first made, it was hardly possible to
give an accurate explanation of them; but since I have ascertained
the manner in which the recurrent and laryngeal nerves are
distributed to the muscles of the larynx, there is no longer any
difficulty. By the division of the eighth pair at the inferior part
of the neck, the dilator muscles of the glottis are paralyzed;
this opening does not enlarge at the moment of inspiration, whilst
the constrictors, which receive their nerves from the superior
laryngeal, preserve their action entire, and shut more or less
completely the glottis.
When the division of the eighth pair does not close the glottis
so completely as to produce death immediately, another order of
phenomena is developed.
The respiration is at first embarrassed, and its rhythm often
experiences a remarkable alteration; the inspiration is slow, and
the expiration quick and short. The animal is averse to motion and
seems to be easily fatigued. At first the formation of the arterial
blood is not prevented, but soon its vermilion colour changes, it
becomes darker and approximates more and more that of the venous
blood. The temperature falls, and the very embarrassed respiration
is only made by the aid of all the muscular powers; the coldness
becomes evident, and the animal soon dies.
As this series of circumstances is developing, the animals, on
whom the experiments are made, consume less oxygen, and form less
carbonic acid.
We find, on opening the body, the bronchia filled with a frothy,
and sometimes a bloody fluid; the lungs are engorged, and the
divisions of the pulmonary artery are much distended with very
black blood.
From all that has now been stated, it is natural to conclude that,
in this last case, the animals die because respiration can no
longer be effected, the lungs being so altered that the air cannot
get into the bronchial cells. To this cause should be added also
the difficulty which the blood experiences in passing from the
arteries to the pulmonary veins.
[111] These words _passion_, _emotion_, _affection_, &c. have, I
know, real differences in the language of metaphysicians; but as
the general effect of the sensations which they express is always
the same on the organic life; as this general effect is what alone
concerns me, and as the secondary phenomena are of no importance, I
use these words indifferently for each other.
[112] We have said in a preceding note, that the division of the
nerves of the eighth pair could produce death in two ways; first,
by closing the glottis, and preventing the entrance of the air into
the air tubes; secondly, by altering the lungs and preventing the
production of the chemical phenomena. Of these two kinds of death
the first is in some measure accidental; it is an indirect effect
of the interruption of the action of the brain; but it is not so
with the second, and though it may not be instantaneous, it is not
less a direct effect of the division. It might be supposed that
the motions of the glottis being destroyed, and the entrance of
the air being rendered consequently more difficult, that it is in
consequence of this obstruction that respiration is embarrassed,
and that the alteration of the lungs is only a consecutive
phenomenon. But in the experiments made by M. Dupuy at Alfort,
a free passage was given to the air, by an opening made in the
trachea. Now it cannot be believed that the small wound necessary
for this opening, could contribute to produce the disturbance of
the respiration, for a similar operation is daily performed on
horses, without producing the slightest inconvenience.
[113] The experiments of Legallois have clearly proved, that this
point is at the origin of the nerves of the eighth pair.
CHAPTER XI.
OF THE INFLUENCE OF THE DEATH OF THE BRAIN OVER THAT OF THE HEART.
In the preceding chapter we have shewn how the lungs remain
inactive, when the brain ceases to act.--The same phenomenon, under
the same circumstances, takes place also in the heart, and must
happen either immediately or mediately.
I. _Does the Heart cease to act immediately in consequence of the
interruption of the cerebral action?_
The greater number of medical men, speak in much too vague a manner
of the cerebral influence. They do not sufficiently determine its
extent and limits, with respect to the different organs of the
system.
It is evident that we shall have answered the question proposed at
the head of this section, if we can determine what the influence of
the brain is with regard to the heart. Now, we have every reason to
suppose, that no direct influence is exercised by the former over
the latter of these organs, which, on the contrary, is immediately
dependent with regard to its operations, on the movement
communicated to it by the blood. This assertion is by no means a
new one. It has been admitted by all sound physiologists; but as
many opinions in medicine are founded upon a contrary principle,
it will not be amiss to dwell upon it a little. It is equally
demonstrated both by observation and experiment--and to begin with
the former:
1st, All violent irritation made upon the brain, produces either
partial, or general convulsion in the muscles of the animal life.
Examine those of the organic life, on the contrary, and little will
be found amiss in their actions.
2dly, All compression of the cerebral mass, whether made by pus,
water or blood, has ordinarily the effect of paralyzing the
voluntary muscles; but so long as the affection does not extend to
the muscles of the breast, the action of the heart is in no degree
diminished.
3dly, Opium and wine, when taken in a certain quantity, diminish
the cerebral energy for the moment and render the brain unfit for
the functions of the animal life. The action of the heart, on the
contrary, is increased.
4thly, In palpitation, and the different irregular movements
of the heart, it is not observable that the principle of these
derangements exists in the brain.--In this respect, as well as on
the subject of syncope, Cullen has been mistaken. The brain during
such time, continues in action as usual.
5thly, The numerous phenomena of apoplexy, and epilepsy, and
concussion, &c. do certainly all of them tend to shew, how
independent the heart is of the brain.
6thly, Every organ which is subject to the direct influence of the
brain, is for that very reason an organ of volition. Now, I should
suppose, that few persons of the present day, would be inclined to
maintain with Stahl, that the heart is among the number of such
organs. What would life be, were we able at will, to suspend the
action of the organ, by which the system is animated? From simple
observation, then, we might conclude, that it is not immediately
that the heart ceases to act, when the functions of the brain
are interrupted, but this fundamental datum of physiology and
pathology, we shall further establish, upon actual experiment.
1st, If the brain of an animal be exposed, and irritated either
with mechanical or chemical agents, a variety of alterations will,
indeed, be produced in the organs of the animal life, but none in
the heart, so long as the muscles of the breast continue to perform
their functions.
2dly, Experiments made in the same manner upon the spinal marrow of
the neck, present the same results.
3dly, If the eighth pair of nerves be irritated, the movements of
the heart will not be accelerated; they will not be arrested if
these two nerves be divided. In all these experiments, however, we
must be careful to make a proper distinction between the emotions
and passions of the animal, and what it really suffers from the
experiment.
4thly, The nature of the great sympathetic nerve, I suppose to be
known;[114] now if the same experiments be made on the cardiac
branches of this nerve, as were made upon the eighth pair, the same
results will follow.
I do not offer in detail the whole of these experiments; the
greater part of them are well known: I was induced to repeat them,
as authors are not agreed upon their consequences.
The experiments of galvanism, are well calculated to throw light
upon the relations existing between the heart and the brain; these
I have taken care to repeat with the utmost exactness, and whatever
authors may have advanced, they are all in favour of the above
opinions--for 1st, If the galvanic apparatus be applied to the
brain, and to the heart, and inferior extremities of a frog, and
the communication made between the metals, there will constantly be
seen a strong contraction in the muscles of the limb, and little or
none in the heart. The same will be the case, to whatever voluntary
muscle the zinc be applied. 2dly, The same results will be had, on
the communication being made between the metals applied on the one
hand to the spinal marrow above the giving off of the sympathetic,
and on the other hand to the heart, and any of the voluntary
muscles.
3dly, On establishing a communication between the metals applied
to the cardiac nerves, and to the heart of the animal, there
has been no contraction in the heart. In all these essays, the
natural disposition between the parts which serve to unite the two
organs, is preserved: there are other experiments which consist in
detaching the heart from the breast. 2dly, In placing two points of
its surface in contact with two different metals. 3dly, In making
the communication between them with a third. From this experiment,
Humboldt and other philosophers have procured contractions, but I
have taken care to repeat it with the greatest accuracy, and must
assert, that I have seen little or nothing of the kind; indeed, if
I had, I should have concluded nothing from it; for it appears to
me, that to decide upon the influence of the brain over the heart,
a portion at least of the nervous system, should be in contact with
one of the metals.
I shall now pass to my experiments on red and warm-blooded animals.
They are necessary for the decision of the question before us, as
the mode of contractility in these animals differs much from that
of the animals submitted to the experiments already mentioned.
1st, In the winter of the year 1798, I was authorized to make
different essays on the bodies of persons who had been guillotined.
I had them at my disposal thirty or forty minutes after they
had undergone the punishment. In some of them, all mobility was
extinct; in others, this property could be reanimated in all the
muscles by the common agents, and in those of the animal life, by
galvanism especially.[115] Notwithstanding which, I could never
occasion the least motion, in applying the apparatus either
to the spinal marrow and the heart, or to this latter organ
and the nerves, which it receives from the ganglions of the
sympathetic, or the par vagum. Nevertheless, the common mechanical
excitant, immediately applied to the fleshy fibre, occasioned
its contraction. Could this have happened in consequence of the
separation of the nervous fillets from the brain? assuredly not;
because the voluntary muscles were equally separated from it,
and yet affected strongly. If any doubt remain, the following
experiments will clear it up.
2dly, In dogs and guinea pigs, I have repeatedly applied the
metals, first to the brain and the heart, then to the trunk of the
spinal marrow, and the heart; then to the par vagum and the heart.
The communication being made, was followed by no apparent result.
3dly, On making the communication between the metals, when applied
to the cardiac nerves and the heart, there was no very sensible
motion.
4thly, Humboldt has asserted, that when the heart is speedily
detached with some of its nervous threads about it, a contraction
may be excited, by arming the nerves with a metal, and then by
touching this metal with another. I have many times tried this
experiment in vain. I confess, however, that once it appeared to me
to succeed.
5thly, On the contrary, I have almost always succeeded in producing
contractions in the heart, by cutting it away from the breast,
and making a communication between a couple of metals, applied to
different points of its surface. This, if I am not mistaken, is
the only means of evidently producing the phenomena of galvanism
in this organ, but with respect to our present question, the
experiment is wholly inconclusive.
All these experiments I have repeated many times, and with the most
scrupulous precautions, nevertheless I do not pretend to call in
question the reality of those results, which other physicians have
remarked. It is well known how very variable those experiments
are, which have the vital powers for their object. Besides, in
admitting even these different results, I do not see how it is
possible to refuse acknowledging, that with respect to the stimulus
of galvanism, there is a wide difference between the susceptibility
of the muscles of the animal life, and those of the organic life.
Again, supposing that the galvanic phenomena were the same in
both sorts of muscles, the fact would prove nothing more, than
that these phenomena with regard to their succession, follow
laws directly the contrary of those, which are displayed in the
phenomena which take place, when any common cause of irritation is
applied to the nerves and their corresponding muscles.
The proofs adduced, will allow us to conclude, that the brain
exercises no direct influence over the heart, and consequently,
that when it ceases to act, the functions of the latter must be
interrupted indirectly.
II. _In case of lesion of the brain, is the death of the heart
occasioned by that of any intermediate organ?_
When the brain dies, the heart dies, but not directly. There must
be some intermediate organ then, the death of which occasions that
of the heart.[116] That intermediate organ is the lungs. In this
sort of death, the following is the series of the phenomena which
may be observed.
1st, The cerebral action is interrupted. 2dly, The action of
all the muscles of the animal life, and consequently of the
intercostals and diaphragm, is annihilated. 3dly, The mechanical
functions of the lungs are suspended. 4thly, The like ensues with
respect to their chemical functions. 5thly, The fibres of the
heart are penetrated with black blood. 6thly, The fibres when so
penetrated, die.
Such sort of death then, has much resemblance with that which is
occasioned by the different asphyxiæ. It is only more sudden, and
that for reasons which I shall presently point out. The following
experiments are an evident proof that the phenomena take place as
I have described them to do.
1st, I have always found black blood in the red-blooded system of
all animals, killed by concussion or compression of the brain; the
heart livid, and the different surfaces coloured as in asphyxia.
2dly, I opened the carotid artery of a dog; the red blood instantly
gushed out, but was immediately suppressed, and the artery tied.
I then killed the creature, by striking him with violence on the
occipital bone.[117] The animal life, and consequently both the
mechanical and chemical functions of the lungs, were suddenly
suppressed. The artery was then united. It poured forth the black
blood with a feeble jet, for some little time, and after some
minutes, the heart entirely ceased to move.
3dly, I have always obtained a similar result in opening the
arteries of different animals which I afterwards killed, either by
dividing the marrow between the first vertebra and occiput, or by
strongly compressing the brain, which I had previously exposed.--It
is thus also that animals perish, by the carotids of which a
deleterious substance has been injected.
4thly, The preceding experiments explain the reason why the blood
is black which flows from the arteries of animals, which are bled
in our slaughter-houses, after having been knocked in the head.
If the blow has been violent, the blood issues such as it was in
the veins, but if the action of the diaphragm and intercostals has
only been weakened by the blow, the redness of the blood is only
diminished.
The state in which the respiration may be (and it is altered from
a variety of circumstances during profuse hemorrhagy) occasions a
great variety in the colour of the arterial blood: hence we have
the reason why it is found of so many different shades in the great
operations of surgery. At the beginning of these, it often flows
out quite red; at the end of them, is sometimes almost black. The
easy or embarrassed state of the respiration of the patient, is the
occasion of these varieties. This I have frequently remarked, when
attending Desault, and was often struck with the appearance, before
I knew the cause of it.
I have never found any relation whatever, between the obscure
colour of the blood, and the compression exercised above the
artery, as some have asserted to take place. There is, indeed, a
connection between the colour and the impetuosity of the jet, but
the reason of this is evident to any one who has read the foregoing
pages.
To return to the point of doctrine on which we are at present
occupied, I am persuaded from the considerations and experiments
which are adduced in the course of this chapter, that the manner
in which the heart ceases to act, when the cerebral functions are
suspended, can no longer admit of a doubt, and that we may resolve
the question proposed, in affirming that under such circumstances,
the death of the heart is occasioned through the medium of that of
the lungs.
There is this difference, then, between the death of the heart,
in consequence of that of the brain, and the death of the brain
in consequence of that of the heart, that the one is indirect,
the other direct, as we have already seen. If some men, as Stahl
asserts, have really been able to suspend the movements of the
heart, the fact is not a proof of the influence of the mind over
the muscles of the organic life, but of its power over the
mechanical, and consequently, the chemical phenomena of respiration.
In red and cold-blooded animals, the death of the heart does not
succeed the death of the brain so quickly as it does in red and
warm-blooded animals. Cut off the head of a frog, and the heart
will continue to beat for some time afterwards. This phenomenon
will be easily accounted for, if we recollect that respiration with
these animals may be suspended a length of time, without arresting
the movements of the heart.
In fact, as the heart dies only because the lungs die in the
first place, when the cerebral functions are interrupted, it is
plain that there ought to exist between the violent death of the
heart and that of the brain, an interval nearly equal to that
during which, in the natural state, there may be a suspension of
respiration.
FOOTNOTES:
[114] Physiologists have paid much attention to the great
sympathetic nerve. They have made, in relation to its uses, many
conjectures but few experiments; so that we have not on this
subject any very precise notions. The deep situation of the
ganglions renders them almost inaccessible, the superior cervical
is almost the only one that can be taken out without producing
death. M. Dupuy, Professor of the Veterinary School at Alfort, has
discovered a method by which he can remove them with ease. We shall
now relate some of his observations.
“_1st Experiment._ The first experiment was made on a young and
vigorous horse, who had been treated for the glanders; it soon
appeared that he was not affected with it, and that it was merely
the caries of a tooth that had led to the belief of the existence
of the disease.
“On the 24th of June his left guttural ganglion was extirpated.
Soon after the operation, the eye of that side appeared to be
more sunk in its socket, the eyelids were swelled and the pupil
contracted.
“On the 28th of June the sub lingual ganglion appeared swollen,
hard and attached; a discharge of fetid, greyish matter was
discovered in the nostril of the same side.
“On the 29th of June, the wound suppurated copiously.
“From the 30th of June till the 16th of July the wound advanced
rapidly towards cicatrization.
“From the 18th of July to the 15th of August the animal continued
in the same state of health.
“On the 15th of August, the right guttural ganglion with a portion
of the nerve was removed; this operation was followed by the
same phenomena as the preceding, with this difference, that two
days after the animal could not swallow water, it run out at the
nostrils. There was in fact a communication between the nostrils
and mouth from the caries of the back molar tooth, the roots of
which were opposite the maxillary sinus, that had an opening into
the nostril; the voice was lost.
“On the 20th of August, he was much emaciated, with the skin dry
and adherent; the cheeks, below the jaw, were constantly moistened
with sweat, which had been observed for twelve or fifteen days. The
wound of the right side remained fistulous; the skin was covered
with scurf, the sheath and scrotum, as well as the hind legs, were
oedematous; the animal died. Nothing remarkable was discovered on
dissection. Below the sub-occipital foramen the great sympathetic
was slightly swelled, in the form of a knot, in the place where the
division had been made.”
“_2d Experiment._ On the 26th of April, the right guttural
ganglion, with a portion of the nerve, was removed from a sound
horse, four and a half years old, strong and in good condition.
The ganglion of the left side was first a little mutilated, and
the nerve was removed posteriorly to the extent of thirty three
centimetres. The animal did not manifest so much pain as might have
been expected.
“The conjunctiva soon became red and the eyelids partly covered the
eyes; the respiration became painful and loud; the pulse was hard,
strong and frequent. The animal refused all food, and drank with
great difficulty.
“This state continued till the 10th of May following. The two
wounds were almost healed; the animal eat and drank well; but the
hind legs and scrotum were still so much swollen as to interfere
with his walking; the conjunctiva remained red and the pupil
contracted.
“Towards the 13th of May the skin became adherent and covered with
scurf; the cutaneous respiration was nearly destroyed.
“On the 25th of May, the swelling of the legs and the scrotum
became considerable, notwithstanding the frictions with water and
turpentine, which were made several times a day since the 13th; he
could, with difficulty be got out of the stable to be examined. The
pulse retained its hardness and frequency. The dung was hard, black
and small.
“During the month of June the phenomena were similar to those we
have enumerated; the swelling of the scrotum and the legs resisted
the tonic and stimulating applications.
“On examining the body, the ends of the nerves that had been drawn
out were found swollen as in the first horse. Similar results have
been obtained in all the other experiments that have been made on
this subject. It may be said in conclusion, that the phenomena
which appear after the removal of this ganglion, and which do
not depend on the operation, are the contraction of the pupil,
the redness of the conjunctiva, general emaciation, accompanied
with swelling of the legs, and a scurfy eruption which ultimately
affects the whole cutaneous surface.”
[115] Galvanic experiments have at different times been made on the
bodies of those who have been executed. Vassali, Julio and Rossi
made a great number of them at Turin; but the piles that were then
used were very weak compared with those that are now employed. In
the experiments made at Newgate on the body of a criminal, the
limbs were violently agitated, the eyes opened and shut, the mouth
and the jaws moved in every direction, and the face was thrown
into the most frightful convulsions. The last and most complete
experiments, that we know of, were made at Glasgow in November 1818
by Dr. Andrew Ure. He used for these experiments a battery composed
of two hundred and seventy pair of plates four inches square, with
communicating wires, and so arranged that they could be insulated
for the purpose of applying the electricity in a more convenient
manner.
The subject, on whom these experiments were made, was of middle
height, about thirty years of age and of an athletic constitution.
He was on the gallows almost an hour, and he was not convulsed
after being hung, whilst a robber executed at the same time was
violently agitated for a considerable time. He was carried to the
anatomical theatre of the university, about ten minutes after he
was removed from the gallows. His face had a perfectly natural
appearance being neither livid nor swollen, and the neck was not
dislocated.
About five minutes before the arrival of the police officers with
the body, the battery was charged with diluted nitro-sulphuric
acid, which quickly put it in a state to exert an intense action.
_1st Experiment._ A large incision was made immediately below the
occiput. The posterior half of the first vertebra was then removed
and the spinal marrow laid bare, at the same time a considerable
incision was made in the great glutæus muscle, in order to expose
the sciatic nerve. A slight incision was made in the heel; no blood
escaped from any part. A wire which communicated with one extremity
of the battery was put in contact with the spinal marrow, whilst
the other was applied to the sciatic nerve. All the muscles of the
body were in an instant agitated with convulsive motions which
resembled a violent shuddering. The strongest convulsions were on
the left side; at each time of renewing the electric contact by
moving the second wire from the haunch to the heel the knee being
previously bent, the leg was thrown out with so much force, that it
threw down one of the assistants who in vain endeavoured to prevent
the extension.
_2d Experiment._ The left phrenic nerve was laid bare towards the
external edge of the sterno-thyroideus muscle, three or four inches
above the clavicle; as this nerve goes to the diaphragm, and as it
communicates with the heart by the eighth pair, it was expected,
that by throwing the galvanic fluid through it, the action of
respiration would be renewed. In consequence a small incision
having been made under the cartilage of the seventh rib, the point
of an insulated wire was placed in contact with the diaphragm,
whilst the other was applied to the phrenic nerve of the neck. This
muscle, the principal agent of respiration, contracted immediately,
but with less force than was expected. As I knew by numerous
experiments that we could produce the most powerful effects from
the galvanic fluid, by leaving the extreme communicating wires
perfectly in contact with the parts on which we wished to operate,
whilst, in order to complete the electric chain, we carried the
end of the wires the length of the plates, into the last trough
of one of the poles and immediately plunged the other wire into
the last cell of the opposite side, I had recourse to this measure
without loss of time. The success was truly astonishing; instantly
commenced a strong and laborious respiration. The chest rose and
fell; the abdomen was pushed forward and then flattened, and the
diaphragm contracted and relaxed. All these motions appeared
without interruption as long as I continued the electric excitement.
In the opinion of many scientific persons who were witnesses of
this scene, this experiment was perhaps the most striking that
had ever been made with an electrical apparatus. It should be
recollected that during half an hour at least, before this, the
body had been nearly exhausted of blood and the spinal marrow had
been much lacerated.
No pulsation could be perceived either in the heart or at the wrist.
_3d Experiment._ The suborbitar nerve was laid bare at its
exit from the suborbitar foramen. One of the conducting wires
was applied to the nerve and the other to the heel; the most
extraordinary grimaces were produced. All the muscles were put
simultaneously in action in a frightful manner; rage, horrour,
despair, anguish and frightful smiles united their hideous
expression in the face of the assassin. At the sight of this, many
of the spectators were obliged to leave the room and one of them
fainted.
_4th Experiment._ The last galvanic experiment was made by
transmitting the electric fluid from the spinal marrow to the
cubital nerve near the elbow; the fingers moved quickly like those
of a performer on a violin; one of the assistants who endeavoured
to keep the hand shut, found that it opened in spite of his
efforts. A wire was applied to a slight incision made at the end of
the first finger; the hand had been previously shut; the finger was
instantly extended, and, after a convulsive agitation of the arm,
the dead man seemed to point his finger at the spectators, some of
whom thought that he had come to life.
An hour was consumed in these experiments.
[116] It is shewn by the beautiful experiments of M. Legallois,
that the heart derives the principle of its forces from the spinal
marrow, and from the whole spinal marrow, since the destruction of
one of its three portions can arrest completely the circulation.
The destruction of the spinal marrow does not entirely annihilate
the motions of the heart; but it weakens them sufficiently to
prevent the circulation, and this weakening is so much the greater,
as the portion of spinal marrow destroyed is larger. It may be
presumed from this, that notwithstanding the weakening which
follows the removal of a part of this marrow, the circulation
may still continue if we lessen the sum of the forces which the
heart must expend to maintain it. For this it is only necessary to
diminish by ligatures on the arteries, the extent of the circle to
which the heart distributes the blood. This conjecture is confirmed
by experiment. It has been seen, for example, that the destruction
of the marrow which is very suddenly fatal in full grown rabbits,
ceases to be so, if before doing it the abdominal aorta is tied
between the coeliac and the superior mesentric arteries. The
application of the same principle to other parts of the body leads
to a still more surprising result, it is this, that in order to
support life in rabbits of a certain age, after having destroyed
the cervical marrow, it is necessary first to cut off the head.
They will be completely dead if the marrow be destroyed before they
are decapitated; this arises from the fact, that by cutting off the
head all this part is taken out of the domain of the circulation,
and that by it the heart having need of less force to continue
its function, we can weaken it by the destruction of the cervical
marrow without its ceasing to perform it.
[117] When an animal is thus struck, it is not certain that the
concussion has not extended its effects upon a greater or less
part of the spinal marrow; and it is not known consequently if the
motions of the heart would not cease, even when asphyxia might be
prevented by means of artificial respiration.
CHAPTER XII.
OF THE INFLUENCE OF THE DEATH OF THE BRAIN OVER THAT OF ALL THE
ORGANS.
When the brain dies, the animal life dies, for the functions of
this life, either directly or indirectly, have their seat in the
brain. It is manifest, that all the operations and affections of
the mind, together with sensation, locomotion, and the voice, must
be put an end to in such case. The difficulty then respects the
functions of the organic life.
I. _Is the interruption of the functions of the organic life a
direct consequence of the cessation of the cerebral actions?_
We shall here adduce both observation and experiment to prove, that
the internal functions are all of them, as well as the action of
the heart, withdrawn from the immediate influence of the brain.
1st, There are a number of diseases affecting the brain, which
occasion so general a suspension of the animal life, as to leave
neither sensation nor voluntary motion, excepting some feeble
oscillations of the intercostals and the diaphragm. In this state
the individual has lost the half of his existence, but the one
half composed of the organic functions, continues in the meanwhile
to subsist, and in many cases with energy. This phenomenon is
exemplified continually in apoplexy, in concussion of the brain,
and extravasation of blood upon its surface.
2dly, During sleep the secretions certainly go on, though Bordeu
insists upon the contrary opinion, with the view of proving the
influence of the nerves over the glands. During a state of sleep,
digestion goes on as usually it does. The exhalations of the
body are made with perfect freedom, and often augmented beyond
their natural quantity; the process of nutrition continues to be
effected, and is probably under such circumstances, increased.
There are many proofs in favor of this opinion; but a state of
sleep is a state of collapse in the brain. Then, neither is the
relaxation of the functions of the internal organs the consequence
of a relaxation of action in the brain, nor the death of the former
the immediate effect of the death of the latter.
3dly, The sleep of animals, which pass a certain part of the year
in a state of torpor, is a very strong proof of the co-existence of
a suspension of the cerebral functions, with a permanent action of
those of the organic life.[118]
4thly, In the different palsies; in those for instance which affect
the lower limbs, and the viscera of the pelvis, in consequence
of some concussion or compression of the medulla spinalis, the
communication of the paralyzed parts with the brain, is either
entirely cut off, or only enfeebled. It is entirely interrupted
when all feeling and power of moving have ceased--it is enfeebled,
when the one and the other of these properties are only enfeebled.
But in these two cases the general and the capillary circulations
continue. The exhalations from the cutaneous surface and in the
cellular substance, are made as usual; the process of absorption
goes on, for without absorption, we should soon see dropsy. The
secretions also are effected, for nothing in such sort of palsy is
more common than a copious secretion of mucus from the bladder.
As for nutrition if it be diminished in energy, the process is
certainly never entirely arrested.
5thly, Spasms and convulsions, which proceed from an unnatural
energy of the cerebral action, have little influence over the
exhalation, secretion, and nutrition of the parts in which they
make their appearance. The trouble and excessive agitation of the
animal life of such parts, compared with the calm of their organic
life, are facts well worthy of remark.
6thly, Fœtuses without heads, in the uterus, possess as active
an organic life, as those which have no defect of conformation
whatever, and sometimes at the time of birth, are monstrous even in
bulk; this circumstance I have frequently had occasion to observe
at my amphitheatre; the functions of nutrition then and circulation
may take place with activity, though deprived of the influence of
the brain:
7thly, In animals, which have no cerebral mass, and in those (the
polypes for instance) where not even a nervous system is apparent,
these organic processes are admirably well conducted,[119] the
greater part of them indeed are common to the vegetable, and the
animal.
8thly, If the different proofs, which Bordeu has given of the
influence of the brain over the functions be well examined, it will
seem that no one of them is decisive. The sudden interruption of
the secreted fluid, in consequence of the division of the nerves
of the part, would be the only proof which I should be inclined to
admit as positive. Now I am not acquainted with any means of making
such division with exactness. We have heard much of an experiment
of this nature upon the parotids; but the disposition of the nerves
distributed to these glands is such, that I have not been even
tempted to repeat the experiment. The testicle is better adapted
for the attempt, and accordingly without touching the vessels, I
divided the spermatic nerves, but an inflammation and a deposit of
matter took place in the gland, and with respect to the secretion
of the semen, I could not judge of the effect of the division of
the nerves. But here this very inflammation coming on without the
influence of the brain, appears to me to infer a possibility of the
seminal secretion under the same circumstances. In this experiment,
the spermatic artery cannot be separated from the plexus which it
receives from the great sympathetic, so intricate is the network
of these nerves about it; their division however is of little
consequence, as they come from the ganglions. It is easy to break
off all communication with the brain, by destroying the lumbar
fillets of nerves.
I might add a number of other considerations to the above, but
here I have to remark that the distinction of the sensibility and
contractility into their two kinds is particularly worth attention.
In fact, the idea of sensibility in our usual way of seeing things,
suggests the idea of the nerves, the nerves again make us think
upon the brain, we associate the three ideas, but excepting for the
animal life they should not be associated. In the organic life, at
least their union is not immediate.
I do not mean to say that the cerebral nerves have no influence
whatever over the organic sensibility, but I maintain that such
influence is not direct and not of the nature of that which is
observed in the animal sensibility.
Many authors have already discovered a number of difficulties
resulting from the opinion which makes the nerves the exclusive
seat of sensibility, they have even sought for other means of
explaining the phenomena of great living bodies. But of its
agents we know as little as we do of its nature, and have no
means of elucidating questions of this sort. Let us be contented
with analyzing, collecting and comparing facts with seizing their
general results; the aggregate of these researches will compose the
true theory of the vital powers; the rest is only conjecture: but
besides the considerations which I have offered, there is another
which manifestly goes to prove that the organic functions are not
under the immediate influence of the brain, and this is, that the
viscera, which perform such functions do not receive their nerves
from the brain but from the ganglions.
This anatomical fact is observable in the liver, the kidney, the
spleen, pancreas, intestines, &c. even in the organs of the animal
life there are nerves which serve for the external, and nerves
which serve for the internal functions. In such the former come
directly from the brain, the latter from the ganglions. Thus the
ciliary nerves, which come off from the opthalmic ganglion, are
those which preside over the secretions and nutrition of the eyes,
the optic nerve which is derived from the brain is the nerve of
vision.[120] In the same way the olfactory nerves of the pituitary
membrane are the agents by which we have the perception of odours,
the threads which come off from the ganglions of Mekel, relate only
to the organic phenomena of the membranes.
Now the nerves of the ganglions cannot transmit the action of the
brain; for we have seen that the nervous system derived from these
bodies should be considered as entirely independent of the nervous
system of the brain; and that the great sympathetic does not derive
its origin from the brain, from the spinal marrow, or from the
nerves of the animal life; but from the ganglions exclusively;
this nerve indeed does not exist, it is only the aggregate of so
many small nervous systems as there are ganglions, which are the
particular centres of the organic life, just in the same way as the
brain is the great and only centre of the animal life.
To establish it as a fact that the great sympathetic such as it
is understood does not in reality exist, I might add a number
of proofs to those, which I have already mentioned. The nervous
communications, which are taken for it, are nothing more than
accessories to the system of the ganglions; for 1st, These nervous
communications, as Cuvier has observed, are not met with in the
necks of birds; between the upper cervical and first thoracic
ganglion there is no vestige of a sympathetic. In birds then,
the upper cervical ganglion is that which in man the opthalmic
ganglion, the ganglion of Mekel and others are. This disposition,
which is natural in birds, agrees with what I have sometimes
observed in the human subject between the first lumbar and the
last thoracic ganglions, as well as between the lumbar and
sacral ganglions themselves. 2dly, In many instances there are
no ganglions in the spot where the pretended sympathetic nerve
communicates with the spinal marrow. This may be seen in the
human neck, and in the abdomen of fish, but such disposition
should be thus regarded. The inferior cervical ganglion furnishes
a great branch which ascends to the superior cervical ganglion,
and establishes between the two a direct communication; but in
ascending it distributes many branches to each of the cervical
nerves, which form a secondary communication.
If we reflect on these considerations, together with those
which have been already offered, we shall be more and more
convinced--1st, That the great sympathetic is only an assemblage
of small nervous systems, having each of them a ganglion for its
centre, and all of them independent of each other, though generally
communicating with the spinal marrow and between themselves.
2dly, That the nerves belonging to these small systems, cannot be
considered as a part of the great nervous system of the animal
life. 3dly, That the organs, which are provided exclusively with
the nerves, are not under the immediate influence of the brain.
Notwithstanding which, we must not suppose that all the organs
which serve for the internal functions, receive their nerves
exclusively from the ganglions: many of these organs are furnished
from the brain, and yet from experiment, it is found that they are
not under the immediate influence of the brain.
As yet we have only observation and reasoning for the basis of the
important principle which we are labouring to establish, namely,
that the organic functions are not directly put a stop to in
consequence of the death of the brain; but experiments upon living
animals are not a less evident demonstration of this principle.
1st, I have always observed, that in producing palsy or convulsion,
I have never been able to impair in any very sensible or sudden
manner, either the exhalation, the absorption, or the nutrition of
the convulsed or palsied part.
2dly, It has been for a long time known, that no spasm of the
muscular fibres of the stomach, bladder, or intestines, can be
produced by irritating the nerves of the ganglions which go to
these organs.
3dly, The division of the nerves of the ganglions, will not
immediately paralyze the hollow organs. Their vermicular motions
continue for a long time after the experiment.
4thly, With respect to the stomach, intestines, bladder and uterus,
I have repeated the galvanic experiments which, with respect to
the heart, have already been mentioned at length; but never could
obtain contractions.[121]
5thly, The same experiments being made upon the organic muscles,
and the great sympathetic nerve of a dog, there was no contraction.
6thly, The issue of the latter operation may be easily conceived,
according to our manner of regarding things. In fact, the
ganglions, which are situated between the gastric organs and the
nervous trunk of the chest, might possibly have interrupted the
series of the galvanic phenomena. With a view, then, to remove
all doubt of this kind, I exposed the nerves, which go from the
ganglions immediately to the stomach, bladder and rectum, and in
this way galvanised the organs but no contraction appeared to me to
be the result of the experiment; at least no contraction, which I
could suppose to be the effect of galvanism, for here I cannot too
much recommend a proper distinction to be made between that which
should be the effect of this fluid, and that which results from the
mechanical contact of the metals.
7thly, These experiments are not easily made upon the intestines,
on account of the tenuity of their nerves; but as these nerves
compose a very perceptible plexus about the mesenteric artery, the
intestine may be galvanized by surrounding the artery with one of
the metals, while the other is placed under the intestinal tube.
This experiment I have made, but could not obtain any sensible
result.
8thly, The preceding essays were made upon warm and red-blooded
animals. Similar attempts were repeated on cold and red-blooded
animals, but with no effect.
9thly, The nerves which immediately supply the gastric organs of
the frog, are so delicate as to make it an extremely difficult
matter to get them into proper contact with the zinc: a small
contraction of the stomach was, however, obtained by Jadelot on
operating directly on these nerves; but this contraction was
similar, no doubt, to those which I have so frequently observed
in other experiments, and not to be compared to the astonishing
effects which are observable in the voluntary muscles. I shall
conclude, therefore, that with respect to the galvanic phenomena,
there exists a wide difference between the muscles of the animal
life and those of the organic life.
I have now collected proof enough, I trust, for resolving, with
certainty, the question proposed in the above chapter, and for
establishing it as a fundamental principle.--1st, That the brain
does not directly influence the organs and the functions of the
internal life; and 2dly, That, therefore, the interruption of these
functions, in case of any great lesion of the brain, is not an
immediate effect of such lesion.
Nevertheless, I am far from considering the cerebral action as
foreign entirely to the organic life. I only maintain that its
influence upon it is indirect, and as yet but little known. I have
been somewhat prolix upon this subject; for certainly nothing in
medicine is more vague than the sense which is commonly attached to
the words _nervous action_, _cerebral action_, &c. There is never a
proper distinction made between that which belongs to one life, and
that which is the attribute of the other. Cullen, in particular,
may be reproached with having exaggerated the influence of the
brain.
II. _Is the interruption of the functions of the organic life, the
indirect effect of the cessation of the cerebral action?_
The organic life continues to subsist for a certain time, after the
apparent death of the individual. There must be some intermediate
agents then, the cessation of the action of which, occasions the
death of the inward organs. Such agents are chiefly the mechanical
organs of respiration. The series of the phenomena are the
following:
1st, The cerebral actions are interrupted.--2dly, The mechanical
functions of the lungs are put an end to.--3dly, There is an
annihilation of their chemical functions.--4thly, The black blood
circulates in all the parts.--5thly, The movement of the heart and
the action of all the parts is weakened.--6thly, Suspended.
All the inward organs then, die nearly as they do in asphyxia;
that is to say--1st, Because they are penetrated by the black
blood.--2dly, Because the circulation ceases to communicate that
motion which is essential to their life.
Nevertheless, there are many differences between death from
asphyxia, and death from lesion of the brain. 1st, The animal
life in the latter sort of death, is generally interrupted at the
very instant of the shock or blow. In the former it is terminated
only in proportion as the black blood penetrates the substance
of the brain.--2dly, In the greater number of the asphyxiæ,
the circulation does not immediately cease, the blood is only
gradually blackened, and continues for some time to be moved
onwards by the agitation of such parts as are still under the
influence of the brain. On the contrary, in lesion of the brain,
the interruption of respiration is sudden; the blood also loses
its red colour at once: on the other hand, the animal life being
suddenly arrested, the organs of volition become immovable on the
spot, and are capable no longer of favouring the motion of the
blood. This remark is particularly applicable to the breast, the
parietes of which facilitate very much the pulmonary circulation,
and even the movements of the heart by their rise and fall, for in
such alternation of motion consists the true influence which the
circulation receives from the respiratory process.
But after all, these two sorts of death may be more or less
similar to each other according to the way in which they happen.
The differences which I have pointed out are by no means general.
Thus, when asphyxia is sudden, as when for instance the air of the
lungs is pumped out with a syringe, there are neither livid spots,
or fulness of the lungs to be met with. The circulation ceases
quickly, and the phenomena of death are such as are observable when
the brain is suddenly destroyed.
On the contrary, if the death of the brain be slow, and the process
of respiration for a certain time continued, the capillary system
of the lungs will be gorged with blood, and the general capillary
system be filled also. The circulation in such case will be slow
to cease, and the phenomena of death like those of many of the
asphyxiæ. Thus the promptitude or slowness of death, proceeding
from lesion of the brain, will occasion all the differences.
It has been often a question in what way criminals die, who are
hanged. In some, the vertebral column is luxated, and in others,
want of respiration is the cause of death.[122] But whenever there
is luxation, there is at the same time asphyxia, and in such
case asphyxia is produced, both because the pressure of the cord
intercepts the passage of the air, and because the intercostals and
diaphragm are paralyzed.
From what I have now said, a comparison may be made between the
three kinds of death upon which I have expatiated. This comparison,
according to my ideas, is of importance: I shall give some features
of it. Generally speaking, there is a greater similarity in the
two modes by which the death of the brain, or that of the lungs
produces the death of the organs, than between either of these
modes, and that, where the death of the heart is followed by the
same effect.
But 1st, There is always black blood in the red-blooded system,
when death begins either by the brain or the lungs. When the
functions of the heart are suddenly suspended, the arterial system
contains a portion of red blood only.
2dly, In the two first cases, the circulation continues for awhile;
in the third, it is immediately suppressed.
3dly, When the death of the organs is a consequence of the death of
the heart, they die, because they cease to receive that excitement,
to which they are accustomed from the motion of the blood. When
their death is produced by that of the brain or lungs, they die not
only because they lose the excitement above-mentioned, but because
they are penetrated by a fluid which is incapable of keeping up
their actions, &c. The reader will easily finish the parallel which
I have thus begun.
In red and cold-blooded animals, the death of the organs succeeds
much more slowly to that of the brain, than in red and warm-blooded
animals. We cannot assign the reason of this fact, because we do
not know the difference of the arterial blood from the venous blood
of these animals, nor the effect which is produced on their organs
by the contact of either sort of blood with them.
When reptiles remain for a length of time under water, does the
arterial blood become black from want of respiration? is the
influx of such blood into their organs, pernicious or not?[123]
or is there a sufficient quantity of air contained in the large
vesicles of the lungs of these animals to oxydate their blood for a
length of time, as but little blood is capable of passing into the
pulmonary artery, which is only a branch of the aorta. The latter
opinion appears to be confirmed by the experiment of injecting the
lungs of a dog with a large quantity of air, in which case the
blood of the creature is reddened for a greater length of time. But
all these questions, notwithstanding the essays of Goodwyn, require
much elucidation.
FOOTNOTES:
[118] When two states, which are not perfectly similar, are
designated by a common name, it is very difficult, whatever care
may be taken to distinguish them, not to apply to one something
which exclusively belongs to the other. This is perhaps one of the
most frequent sources of our errours. In this case, for example, it
does not seem that there is a great inconvenience in designating by
the word sleep the state of torpor of certain animals during a part
of the year. It is well known that we understand by it altogether
a different thing from the sleep, which in warmer seasons of the
year, comes on periodically every day; yet in consequence of
the identity of the name, we are disposed to admit identity of
character and to infer from one respecting the other.
[119] What is the circulation of an animal which exhibits no trace
of vessels? what inferences can be drawn for man from the mode of
nutrition of a polypus? what relation can be established between
the complex function which presides in the mammalia over the
support of the organs, and the kind of imbibition by means of which
the zoophyte is developed and preserved?
[120] The external ciliary nerves only come from a ganglion. The
internal ciliary ones which have precisely the same distribution
and serve also very probably the same uses, come from a cerebral
nerve, from the nasal branch of the ophthalmic.
[121] The galvanic stimulus usually produces very evident effects
upon the contraction of the intestinal tube; these motions are less
evident in the stomach than in any other part of the canal; but
the same difference is always observed whatever be the stimulus
employed.
[122] Death does not always take place in the same way. It has
been remarked, for example, that those who were hung at Lyons
died quicker than those who were hung at Paris. In seeking for
the cause of this difference, it was ascertained that in those
who were executed at Lyons there was almost always a luxation of
the first or the second vertebra, which was owing to a rotatory
motion, which the executioner gave to the criminal in throwing him
from the scaffold. The death was quick, because it was produced by
compression or laceration of the spinal marrow; it was slower in
the other case in which it was only the result of asphyxia.
[123] It appears by the beautiful experiments of M. Edwards that
frogs can live but a very short time in water deprived of air by
boiling. Immersed in a small body of water containing air they
soon die, no doubt after they have exhausted the air held in
solution in the water. They can on the contrary live an indefinite
time in this state of immersion, if care be taken to renew the
water sufficiently often. The same thing happens, and still more
certainly, if they are immersed in running water.
It is not by passing the water through the lungs, as the fish
does through the branchiæ, that the frog obtains the air held in
solution by the water in which he is immersed, the skin is in
this case the sole respiratory organ. M. Edwards is satisfied
that this mode of respiration is not sufficient to support life,
except between certain limits of temperature; a frog immersed in a
volume of water which is not changed, continues to live so much the
longer as the temperature of this fluid approaches nearer 32°. At
this degree frogs are not torpid, as might be supposed, only their
motions are slower.
As long as the animal immersed in the water remains perfectly
alive, which may be known by the vivacity of his motions, it is
certain that the respiratory phenomena continue to be performed
by him; we see in fact on the membranes in the interstices of the
toes, the vessels filled with vermilion blood. When the black
colour begins to appear, the animal soon becomes immoveable and
insensible.
CHAPTER XIII.
OF THE INFLUENCE OF THE DEATH OF THE BRAIN OVER THAT OF THE BODY IN
GENERAL.
From the consideration of what has been said in the preceding
chapter, nothing can be more easy than to form an accurate idea of
the manner in which the phenomena of general death, commencing by
the brain, are concatenated. The series is as follows:
1st, The cerebral action is annihilated. 2dly, There is a sudden
cessation of sensation and voluntary motion. 3dly, A simultaneous
paralysis of the intercostals and diaphragm. 4thly, An interruption
of the mechanical phenomena of respiration and the voice. 5thly,
An annihilation of the chemical phenomena of the lungs. 6thly, A
passage of black blood into the arteries. 7thly, A slowness of
circulation owing to the influx of such blood into the arteries,
and the absolute immobility of all the parts, of the intercostals
and diaphragm in particular. 8thly, The heart dies and the general
circulation ceases. 9thly, The organic life vanishes. 10thly, The
animal heat, which is the product of all the functions, disappears,
11thly, The white organs die.
Though in this kind of death, as well as in the two preceding
kinds, the functions are suddenly annihilated; the parts retain,
for a certain time, a number of the properties of life. The
organic sensibility and contractility, continue for some time, to
be manifest in the muscles of the two lives; and in those of the
animal life, the susceptibility of being affected by the galvanic
fluid is very great in the muscles of the animal life.
This permanence of the organic properties, is nearly the same
in every case; the only cause which affects it, is the slowness
with which the phenomena of death have succeeded each other. In
every case where their duration has been the same, whatever may
have been the cause of death, experiments instituted upon these
properties, are attended with similar results; for it is evident
that concussion of the brain, luxation of the vertebræ, the section
of the spinal marrow, apoplexy, compression of the brain, or
inflammation, are all of them causes which are attended with a like
effect.
The same, however, is not the case with respect to the asphyxiæ
produced by the different gases. We have shown the reason of this
in the more or less deleterious nature of the gases which produce
asphyxiæ.
The state of the lungs also, is very various in the bodies of
persons who have died from lesions of the brain. This organ is
sometimes gorged and sometimes almost empty: it shews, however,
whether the death of the individual has been sudden or gradual. The
same indication may be had from the state of the exterior surfaces.
The death, which is the consequence of disease, commences much more
rarely in the brain, than in the lungs. Nevertheless, in certain
paroxysms of acute fever, the blood is violently carried to the
head, and is the occasion of death. The concatenation of its
phenomena, are then the same as take place in sudden death.
There are a great number of other cases besides those of fever,
where the commencement of death may be in the brain, though the
brain itself may not have been previously affected by the disease.
In these cases, the state of the lungs is very various; but little
can be learnt from it with respect to the nature of the disease.
It is only an indication of the manner in which the functions have
been terminated.
TRANSCRIBER’S NOTE
Footnote [28] is referenced from Footnote [27] not from the text itself.
Footnote [101] is referenced from Footnote [100].
Footnote [108] is referenced from Footnote [107].
Obvious typographical errors and punctuation errors have been
corrected after careful comparison with other occurrences within
the text and consultation of external sources.
Except for those changes noted below, all misspellings in the text,
and inconsistent or archaic usage, have been retained. For example,
air-cells, air cells; economy, œconomy; no-wise, nowise, no wise;
errors, errours; mechanicians; contractility; hemorrhagy; hebetate.
In the main text:
Pg 17, ‘not of the mattter’ replaced by ‘not of the matter’.
Pg 20, ‘its accessaries’ replaced by ‘its accessories’.
Pg 25, ‘TH TWO LIVES’ replaced by ‘THE TWO LIVES’.
Pg 33, ‘make a differerence’ replaced by ‘make a difference’.
Pg 36, ‘at the expence’ replaced by ‘at the expense’.
Pg 58, ‘nearly analagous’ replaced by ‘nearly analogous’.
Pg 59, ‘sudden alteratian’ replaced by ‘sudden alteration’.
Pg 69, ‘whick Authors’ replaced by ‘which Authors’.
Pg 79, ‘it is succeptible’ replaced by ‘it is susceptible’.
Pg 144, ‘at utterence’ replaced by ‘at utterance’.
Pg 149, ‘then the nutrive’ replaced by ‘then the nutritive’.
Pg 173, ‘physiolgist. Now’ replaced by ‘physiologist. Now’.
Pg 173, ‘is ther esult’ replaced by ‘is the result’.
Pg 176, ‘the body ensuses’ replaced by ‘the body ensues’.
Pg 196, ‘which its practicles’ replaced by ‘which its particles’.
Pg 213, ‘cut the treachea’ replaced by ‘cut the trachea’.
Pg 235, ‘is propogated from’ replaced by ‘is propagated from’.
Pg 236, ‘Ex-riments upon’ replaced by ‘Experiments upon’.
Pg 240, ‘to the concominant’ replaced by ‘to the concomitant’.
Pg 248, ‘the venons system’ replaced by ‘the venous system’.
Pg 252, ‘when the functious’ replaced by ‘when the functious’.
Pg 258, ‘swells and cantracts’ replaced by ‘swells and contracts’.
Pg 259, ‘pipe, then when’ replaced by ‘pipe, than when’.
Pg 261, ‘that livid tin’ replaced by ‘that livid tint’.
Pg 278, ‘in sulphureted’ replaced by ‘in sulphurated’.
Pg 278, ‘azot, in pure’ replaced by ‘azote, in pure’.
Pg 293, ‘extensive hemorhagy’ replaced by ‘extensive hemorrhagy’.
Pg 293, ‘have began in’ replaced by ‘has begun in’.
Pg 310, ‘I was authorzied’ replaced by ‘I was authorized’.
Pg 333, ‘of accute fever’ replaced by ‘of acute fever’.
In the Footnotes:
FN 4 (Footnote [4] referenced from) pg 12, ‘the maunmalia’ replaced by ‘the mammalia’.
FN 5 pg 17, ‘opake colour’ replaced by ‘opaque colour’.
FN 5 pg 17, ‘cogulum of milk’ replaced by ‘coagulum of milk’.
FN 13 pg 43, ‘In somnambulition’ replaced by ‘In somnambulism’.
FN 15 pg 57, ‘perfect iudifference’ replaced by ‘perfect indifference’.
FN 27 pg 90, ‘and peritoreum’ replaced by ‘and peritoneum’.
FN 31 pg 105, ‘the duoderum’ replaced by ‘the duodenum’.
FN 31 pg 105, ‘as the ileo-coecal’ replaced by ‘as the ileo-cecal’.
FN 34 pg 118, ‘to the indiosyncrasy’ replaced by ‘to the idiosyncrasy’.
FN 76 pg 206, ‘name of hypocondria’ replaced by ‘name of hypochondria’.
FN 90 pg 236, ‘vena porta, as’ replaced by ‘vena portæ, as’.
FN 92 pg 241, ‘soon ofter grew’ replaced by ‘soon after grew’.
FN 92 pg 241, ‘the plantive cries’ replaced by ‘the plaintive cries’.
FN 103 pg 281, ‘prot-phosphuretted’ replaced by ‘proto-phosphuretted’.
FN 115 pg 311, ‘of middle heighth’ replaced by ‘of middle height’.
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