Title: Fathers of Biology
Author: McRae, Charles
Language: English
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             FATHERS OF BIOLOGY


                     BY
        CHARLES McRAE, M.A., F.L.S.
 FORMERLY SCHOLAR OF EXETER COLLEGE, OXFORD


               PERCIVAL & CO.
        _KING STREET, COVENT GARDEN_
                   LONDON
                    1890



Transcriber's Note:

    Minor typographical errors have been corrected without note. Archaic
    and variant spellings remain as originally printed. Greek text
    appears as originally printed.



PREFACE.


It is hoped that the account given, in the following pages, of the lives
of five great naturalists may not be found devoid of interest. The work
of each one of them marked a definite advance in the science of Biology.

There is often among students of anatomy and physiology a tendency to
imagine that the facts with which they are now being made familiar have
all been established by recent observation and experiment. But even the
slight knowledge of the history of Biology, which may be obtained from a
perusal of this little book, will show that, so far from such being the
case, this branch of science is of venerable antiquity. And, further, if
in the place of this misconception a desire is aroused in the reader for
a fuller acquaintance with the writings of the early anatomists the
chief aim of the author will have been fulfilled.



CONTENTS.


                      PAGE

 HIPPOCRATES             1

 ARISTOTLE              19

 GALEN                  45

 VESALIUS               63

 HARVEY                 83



HIPPOCRATES.



_HIPPOCRATES._


Owing to the lapse of centuries, very little is known with certainty of
the life of Hippocrates, who was called with affectionate veneration by
his successors "the divine old man," and who has been justly known to
posterity as "the Father of Medicine."

He was probably born about 470 B.C., and, according to all accounts,
appears to have reached the advanced age of ninety years or more. He
must, therefore, have lived during a period of Greek history which was
characterized by great intellectual activity; for he had, as his
contemporaries, Pericles the famous statesman; the poets Æschylus,
Sophocles, Euripides, Aristophanes, and Pindar; the philosopher
Socrates, with his disciples Xenophon and Plato; the historians
Herodotus and Thucydides; and Phidias the unrivalled sculptor.

In the island of Cos, where he was born, stood one of the most
celebrated of the temples of Æsculapius, and in this temple--because he
was descended from the Asclepiadæ--Hippocrates inherited from his
forefathers an important position. Among the Asclepiads the habit of
physical observation, and even manual training in dissection, were
imparted traditionally from father to son from the earliest years, thus
serving as a preparation for medical practice when there were no written
treatises to study.[1]

Although Hippocrates at first studied medicine under his father, he had
afterwards for his teachers Gorgias and Democritus, both of classic
fame, and Herodicus, who is known as the first person who applied
gymnastic exercises to the cure of diseases.

The Asclepions, or temples of health, were erected in various parts of
Greece as receptacles for invalids, who were in the habit of resorting
to them to seek the assistance of the god. These temples were mostly
situated in the neighbourhood of medicinal springs, and each devotee at
his entrance was made to undergo a regular course of bathing and
purification. Probably his diet was also carefully attended to, and at
the same time his imagination was worked upon by music and religious
ceremonies. On his departure, the restored patient usually showed his
gratitude by presenting to the temple votive tablets setting forth the
circumstances of his peculiar case. The value of these to men about to
enter on medical studies can be readily understood; and it was to such
treasures of recorded observations--collected during several
generations--that Hippocrates had access from the commencement of his
career.

Owing to the peculiar constitution of the Asclepions, medical and
priestly pursuits had, before the time of Hippocrates, become combined;
and, consequently, although rational means were to a certain extent
applied to the cure of diseases, the more common practice was to resort
chiefly to superstitious modes of working upon the imagination. It is
not surprising, therefore, to find that every sickness, especially
epidemics and plagues, were attributed to the anger of some offended
god, and that penance and supplications often took the place of personal
and domestic cleanliness, fresh air, and light.

It was Hippocrates who emancipated medicine from the thraldom of
superstition, and in this way wrested the practice of his art from the
monopoly of the priests. In his treatise on "The Sacred Disease"
(possibly epilepsy), he discusses the controverted question whether or
not this disease was an infliction from the gods; and he decidedly
maintains that there is no such a thing as a sacred disease, for all
diseases arise from natural causes, and no one can be ascribed to the
gods more than another. He points out that it is simply because this
disease is unlike other diseases that men have come to regard its cause
as divine, and yet it is not really more wonderful than the paroxysms
of fevers and many other diseases not thought sacred. He exposes the
cunning of the impostors who pretend to cure men by purifications and
spells; "who give themselves out as being excessively religious, and as
knowing more than other people;" and he argues that "whoever is able, by
purifications and conjurings, to drive away such an affection, will be
able, by other practices, to excite it, and, according to this view, its
divine nature is entirely done away with." "Neither, truly," he
continues, "do I count it a worthy opinion to hold that the body of a
man is polluted by the divinity, the most impure by the most holy; for,
were it defiled, or did it suffer from any other thing, it would be like
to be purified and sanctified rather than polluted by the divinity." As
an additional argument against the cause being divine, he adduces the
fact that this disease is hereditary, like other diseases, and that it
attacks persons of a peculiar temperament, namely, the phlegmatic, but
not the bilious; and "yet if it were really more divine than the
others," he justly adds, "it ought to befall all alike."

Again, speaking of a disease common among the Scythians, Hippocrates
remarks that the people attributed it to a god, but that "to me it
appears that such affections are just as much divine as all others are,
and that no one disease is either more divine or more human than
another, but that all are alike divine, for that each has its own
nature, and that no one arises without a natural cause."

From this it will be seen that Hippocrates regarded all phenomena as at
once divine and scientifically determinable. In this respect it is
interesting to compare him with one of his most illustrious
contemporaries, namely, with Socrates, who distributed phenomena into
two classes: one wherein the connection of antecedent and consequent was
invariable and ascertainable by human study, and wherein therefore
future results were accessible to a well-instructed foresight; the
other, which the gods had reserved for themselves and their
unconditional agency, wherein there was no invariable or ascertainable
sequence, and where the result could only be foreknown by some omen or
prophecy, or other special inspired communication from themselves. Each
of these classes was essentially distinct, and required to be looked at
and dealt with in a manner radically incompatible with the other.
Physics and astronomy, in the opinion of Socrates, belonged to the
divine class of phenomena in which human research was insane, fruitless,
and impious.[2]

Hippocrates divided the causes of diseases into two classes: the one
comprehending the influence of seasons, climates, water, situation, and
the like; the other consisting of such causes as the amount and kind of
food and exercise in which each individual indulges. He considered that
while heat and cold, moisture and dryness, succeeded one another
throughout the year, the human body underwent certain analogous changes
which influenced the diseases of the period. With regard to the second
class of causes producing diseases, he attributed many disorders to a
vicious system of diet, for excessive and defective diet he considered
to be equally injurious.

In his medical doctrines Hippocrates starts with the axiom that the body
is composed of the four elements--air, earth, fire, and water. From
these the four fluids or humours (namely, blood, phlegm, yellow bile,
and black bile) are formed. Health is the result of a right condition
and proper proportion of these humours, disease being due to changes in
their quality or distribution. Thus inflammation is regarded as the
passing of blood into parts not previously containing it. In the course
of a disorder proceeding favourably, these humours undergo spontaneous
changes in quality. This process is spoken of as _coction_, and is the
sign of returning health, as preparing the way for the expulsion of the
morbid matters--a state described as the _crisis_. These crises have a
tendency to occur at certain periods, which are hence called _critical
days_. As the critical days answer to the periods of the process of
coction, they are to be watched with anxiety, and the actual condition
of the patient at these times is to be compared with the state which it
was expected he ought to show. From these observations the physician may
predict the course which the remainder of the disease will probably
take, and derive suggestions as to the practice to be followed in order
to assist Nature in her operations.

Hippocrates thus appears to have studied "the natural history of
diseases." As stated above, his practice was to watch the manner in
which the humours were undergoing their fermenting coction, the
phenomena displayed in the critical days, and the aspect and nature of
the critical discharges--not to attempt to check the process going on,
but simply to assist the natural operation. His principles and practice
were based on the theory of the existence of a restoring essence (or
φύσις) penetrating through all creation; the agent which is constantly
striving to preserve all things in their natural state, and to restore
them when they are preternaturally deranged. In the management of this
_vis medicatrix naturæ_ the art of the physician consisted. Attention,
therefore, to regimen and diet was the principal remedy Hippocrates
employed; nevertheless he did not hesitate, when he considered that
occasion required, to administer such a powerful drug as hellebore in
large doses.

The writings which are extant under the name of Hippocrates cannot all
be ascribed to him. Many were doubtless written by his family, his
descendants, or his pupils. Others are productions of the Alexandrian
school, some of these being considered by critics as wilful forgeries,
the high prices paid by the Ptolemies for books of reputation probably
having acted as inducements to such fraud. The following works have
generally been admitted as genuine:--

     1. On Airs, Waters, and Places.
     2. On Ancient Medicine.
     3. On the Prognostics.
     4. On the Treatment in Acute Diseases.
     5. On Epidemics [Books I. and III.].
     6. On Wounds of the Head.
     7. On the Articulations.
     8. On Fractures.
     9. On the Instruments of Reduction.
    10. The Aphorisms [Seven Books].
    11. The Oath.

The works "On Fractures," "On the Articulations," "On Injuries to the
Head," and "On the Instruments of Reduction," deal with anatomical or
surgical matters, and exhibit a remarkable knowledge of osteology and
anatomy generally. It has sometimes been doubted if Hippocrates could
ever have had opportunities of gaining this knowledge from dissections
of the human body, for it has been thought that the feeling of the age
was diametrically opposed to such a practice, and that Hippocrates would
not have dared to violate this feeling. The language used, however, in
some passages in the work "On the Articulations," seems to put the
matter beyond doubt. Thus he says in one place, "But if one will strip
the point of the shoulder of the fleshy parts, and where the muscle
extends, and also lay bare the tendon that goes from the armpit and
clavicle to the breast," etc. And again, further on in the same
treatise, "It is evident, then, that such a case could not be reduced
either by succussion or by any other method, unless one were to cut open
the patient, and then, having introduced the hand into one of the great
cavities, were to push outwards from within, which one might do in the
dead body, but not at all in the living."

His descriptions of the vertebræ, with all their processes and
ligaments, as well as his account of the general characters of the
internal viscera, would not have been as free from error as they are if
he had derived all his knowledge from the dissection of the inferior
animals. Moreover, it is indisputable that, within less than a hundred
years from the death of Hippocrates, the human body was openly dissected
in the schools of Alexandria--nay, further, that even the vivisection of
condemned criminals was not uncommon. It would be unreasonable to
suppose that such a practice as the former sprang up suddenly under the
Ptolemies, and it seems, therefore, highly probable that it was known
and tolerated in the time of Hippocrates. It is not surprising, when we
remember the rude appliances and methods which then obtained, that in
his knowledge of minute anatomy Hippocrates should compare unfavourably
with anatomists of the present day. Of histology, and such other
subjects as could not be brought within his direct personal observation,
the knowledge of Hippocrates was necessarily defective. Thus he wrote of
the tissues without distinguishing them; confusing arteries, veins, and
nerves, and speaking of muscles vaguely as "flesh." But with matters
within the reach of the Ancient Physician's own careful observation, the
case is very different. This is well shown in his wonderful chapter on
the club-foot, in which he not only states correctly the true nature of
the malformation, but gives some very sensible directions for rectifying
the deformity in early life.

When human strength was not sufficient to restore a displaced limb, he
skilfully availed himself of all the mechanical powers which were then
known. He does not appear to have been acquainted with the use of
pulleys for the purpose, but the axles which he describes as being
attached to the bench which bears his name (_Scamnum Hippocratis_) must
have been quite capable of exercising the force required.

The work called "The Aphorisms," which was probably written in the old
age of Hippocrates, consists of more than four hundred short pithy
sentences, setting forth the principles of medicine, physiology, and
natural philosophy. A large number of these sentences are evidently
taken from the author's other works, especially those "On Air," etc.,
"On Prognostics," and "On the Articulations." They embody the result of
a vast amount of observation and reflection, and the majority of them
have been confirmed by the experience of two thousand years. A proof of
the high esteem in which they have always been held is furnished by the
fact that they have been translated into all the languages of the
civilized world; among others, into Hebrew, Arabic, Latin, English,
Dutch, Italian, German, and French. The following are a few examples of
these aphorisms:--

    "Spontaneous lassitude indicates disease."

    "Old people on the whole have fewer complaints than the young; but
    those chronic diseases which do befall them generally never leave
    them."

    "Persons who have sudden and violent attacks of fainting without any
    obvious cause die suddenly."

    "Of the constitutions of the year, the dry upon the whole are more
    healthy than the rainy, and attended with less mortality."

    "Phthisis most commonly occurs between the ages of eighteen and
    thirty-five years."

    "If one give to a person in fever the same food which is given to a
    person in good health, what is strength to the one is disease to the
    other."

    "Such food as is most grateful, though not so wholesome, is to be
    preferred to that which is better, but distasteful."

    "Life is short and the art long; the opportunity fleeting;
    experience fallacious and judgment difficult. The physician must not
    only do his duty himself, but must also make the patient, the
    attendants and the externals, co-operate."

Hippocrates appears to have travelled a great deal, and to have
practised his art in many places far distant from his native island. A
few traditions of what he did during his long life remain, but
differences of opinion exist as to the truth of these stories.

Thus one story says that when Perdiccas, the King of Macedonia, was
supposed to be dying of consumption, Hippocrates discovered the disorder
to be love-sickness, and speedily effected a cure. The details of this
story scarcely seem to be worthy of credence, more especially as similar
legends have been told of entirely different persons belonging to widely
different times. There are, however, some reasons for believing that
Hippocrates visited the Macedonian court in the exercise of his
professional duties, for he mentions in the course of his writings,
among places which he had visited, several which were situated in
Macedonia; and, further, his son Thessalus appears to have afterwards
been court physician to Archelaus, King of Macedonia.

Another story connects the name of Hippocrates with the Great Plague
which occurred at Athens in the time of the Peloponnesian war. It is
said that Hippocrates advised the lighting of great fires with wood of
some aromatic kind, probably some species of pine. These, being kindled
all about the city, stayed the progress of the pestilence. Others
besides Hippocrates are, however, famous for having successfully adopted
this practice.

A third legend states that the King of Persia, pursuing the plan (which
in the two celebrated instances of Themistocles and Pausanias had proved
successful) of attracting to his side the most distinguished persons in
Greece, wrote to Hippocrates asking him to pay a visit to his court, and
that Hippocrates refused to go. Although the story is discarded by many
scholars, it is worthy of note that Ctesias, a kinsman and contemporary
of Hippocrates, is mentioned by Xenophon in the "Anabasis" as being in
the service of the King of Persia. And, with regard to the refusal of
the venerable physician to comply with the king's request, one cannot
lose sight of the fact that such refusal was the only course consistent
with the opinions he professed of a monarchical form of government.

After his various travels Hippocrates, as seems to be pretty generally
admitted, spent the latter portion of his life in Thessaly, and died at
Larissa at a very advanced age.

It is difficult to speak of the skill and painstaking perseverance of
Hippocrates in terms which shall not appear exaggerated and
extravagant. His method of cultivating medicine was in the true spirit
of the inductive philosophy. His descriptions were all derived from
careful observation of its phenomena, and, as a result, the greater
number of his deductions have stood unscathed the test of twenty
centuries.

Still more difficult is it to speak with moderation of the candour which
impelled Hippocrates to confess errors into which in his earlier
practice he had fallen; or of that freedom from superstition which
entitled him to be spoken of as a man who knew not how to deceive or be
deceived ("qui tam fallere quam falli nescit"); or, lastly, of that
purity of character and true nobility of soul which are brought so
distinctly to light in the words of the oath translated below:--

    "I swear by Apollo the Physician and Æsculapius, and I call Hygeia
    and Panacea and all the gods and goddesses to witness, that to the
    best of my power and judgment I will keep this oath and this
    contract; to wit--to hold him, who taught me this Art, equally dear
    to me as my parents; to share my substance with him; to supply him
    if he is in need of the necessaries of life; to regard his offspring
    in the same light as my own brothers, and to teach them this Art, if
    they shall desire to learn it, without fee or contract; to impart
    the precepts, the oral teaching, and all the rest of the instruction
    to my own sons, and to the sons of my teacher, and to pupils who
    have been bound to me by contract, and who have been sworn according
    to the law of medicine.

    "I will adopt that system of regimen which, according to my ability
    and judgment, I consider for the benefit of my patients, and will
    protect them from everything noxious and injurious. I will give no
    deadly medicine to any one, even if asked, nor will I give any such
    counsel, and similarly I will not give to a woman the means of
    procuring an abortion. With purity and with holiness I will pass my
    life and practise my art.... Into whatever houses I enter I will go
    into them for the benefit of the sick, keeping myself aloof from
    every voluntary act of injustice and corruption and lust. Whatever
    in the course of my professional practice, or outside of it, I see
    or hear which ought not to be spread abroad, I will not divulge, as
    reckoning that all such should be kept secret. If I continue to
    observe this oath and to keep it inviolate, may it be mine to enjoy
    life and the practice of the Art respected among all men for ever.
    But should I violate this oath and forswear myself, may the reverse
    be my lot."


FOOTNOTES:

[1] Grote's "Aristotle," vol. i. p. 3.

[2] Grote's "History of Greece," vol. i. p. 358.



ARISTOTLE.



_ARISTOTLE._


About the time that Hippocrates died, Aristotle, who may be regarded as
the founder of the science of "Natural History," was born (B.C. 384) in
Stagira, an unimportant Hellenic colony in Thrace, near the Macedonian
frontier. His father was a distinguished physician, and, like
Hippocrates, boasted descent from the Asclepiadæ. The importance
attached by the Asclepiads to the habit of physical observation, which
has been already referred to in the life of Hippocrates, secured for
Aristotle, from his earliest years, that familiarity with biological
studies which is so clearly evident in many of his works.

Both parents of Aristotle died when their son was still a youth, and in
consequence of this he went to reside with Proxenus, a native of
Atarneus, who had settled at Stagira. Subsequently he went to Athens and
joined the school of Plato. Here he remained for about twenty years, and
applied himself to study with such energy that he became pre-eminent
even in that distinguished band of philosophers. He is said to have
been spoken of by Plato as "the intellect" of the school, and to have
been compared by him to a spirited colt that required the application of
the rein to restrain its ardour.

Aristotle probably wrote at this time some philosophical works, the fame
of which reached the ears of Philip, King of Macedonia, and added to the
reputation which the young philosopher had already made with that
monarch; for Philip is said to have written to him on the occasion of
Alexander's birth, B.C. 356: "King Philip of Macedonia to Aristotle,
greeting. Know that a son has been born to me. I thank the gods not so
much that they have given him to me, as that they have permitted him to
be born in the time of Aristotle. I hope that thou wilt form him to be a
king worthy to succeed me and to rule the Macedonians."

After the death of Plato, which occurred in 347 B.C., Aristotle quitted
Athens and went to Atarneus, where he stayed with Hermias, who was then
despot of that town. Hermias was a remarkable man, who, from being a
slave, had contrived to raise himself to the supreme power. He had been
at Athens and had heard Plato's lectures, and had there formed a
friendship for Aristotle. With this man the philosopher remained for
three years, and was then compelled suddenly to seek refuge in Mitylene,
owing to the perfidious murder of Hermias. The latter was decoyed out of
the town by the Persian general, seized and sent prisoner to
Artaxerxes, by whom he was hanged as a rebel. On leaving Atarneus,
Aristotle took with him a niece of Hermias, named Pythias, whom he
afterwards married. She died young, leaving an infant daughter.

Two or three years after this, Aristotle became tutor to Alexander, who
was then about thirteen years old. The philosopher seems to have been a
favourite with both the king and the prince, and, in gratitude for his
services, Philip rebuilt Stagira and restored it to its former
inhabitants, who had either been dispersed or carried into slavery. The
king is said also to have established there a school for Aristotle. The
high respect in which Alexander held his teacher is expressed in his
saying that he honoured him no less than his own father, for while to
one he owed life, to the other he owed all that made life valuable.

In 336 B.C. Alexander, who was then only about twenty years of age,
became king, and Aristotle soon afterwards quitted Macedonia and took up
his residence in Athens once more, after an absence of about twelve
years. Here he opened a school in the Lycæum, a gymnasium on the eastern
side of the city, and continued his work there for about twelve years,
during which time Alexander was making his brilliant conquests. The
lectures were given for the most part while walking in the garden, and
in consequence, perhaps, of this, the sect received the name of the
Peripatetics. The discourses were of two kinds--the _esoteric_, or
abstruse, and the _exoteric_, or familiar; the former being delivered to
the more advanced pupils only. During the greater part of this time
Aristotle kept up correspondence with Alexander, who is said[3] to have
placed at his disposal thousands of men, who were busily employed in
collecting objects and in making observations for the completion of the
philosopher's zoological researches. Alexander is, moreover, said to
have given the philosopher eight hundred talents for the same purpose.

In spite of these marks of friendship and respect, Alexander, who was
fast becoming intoxicated with success, and corrupted by Asiatic
influences, gradually cooled in his attachment towards Aristotle. This
may have been hastened by several causes, and among others by the
freedom of speech and republican opinions of Callisthenes, a kinsman and
disciple of Aristotle, who had been, by the latter's influence,
appointed to attend on Alexander. Callisthenes proved so unpopular, that
the king seems to have availed himself readily of the first plausible
pretext for putting him to death, and to have threatened his former
friend and teacher with a similar punishment. The latter, for his part,
probably had a deep feeling of resentment towards the destroyer of his
kinsman.

Meanwhile the Athenians knew nothing of these altered relations between
Aristotle and Alexander, but continued to regard the philosopher as
thoroughly imbued with kingly notions (in spite of his writings being
quite to the contrary); so that he was an object of suspicion and
dislike to the Athenian patriots. Nevertheless, as long as Alexander was
alive, Aristotle was safe from molestation. As soon, however, as
Alexander's death became known, the anti-Macedonian feeling of the
Athenians burst forth, and found a victim in the philosopher. A charge
of impiety was brought against him. It was alleged that he had paid
divine honours to his wife Pythias and to his friend Hermias. Now, for
the latter, a eunuch, who from the rank of a slave had raised himself to
the position of despot over a free Grecian community, so far from
coupling his name (as Aristotle had done in his hymn) with the greatest
personages of Hellenic mythology, the Athenian public felt that no
contempt was too bitter. To escape the storm the philosopher retired to
Chalcis, in Eubœa, then under garrison by Antipater, the Governor of
Macedonia, remarking in a letter, written afterwards, that he did so in
order that the Athenians might not have the opportunity of sinning a
second time against philosophy (the allusion being, of course, to the
fate of Socrates).

He probably intended to return to Athens again so soon as the political
troubles had abated, but in September, 322 B.C., he died at Chalcis. An
overwrought mind, coupled with indigestion and weakness of the stomach,
from which he had long suffered, was most probably the cause of death.
Some of his detractors, however, have asserted that he took poison, and
others that he drowned himself in the Eubœan Euripus.

It is not easy to arrive at a just estimate of the character of
Aristotle. By some of his successors he has been reproached with
ingratitude to his teacher, Plato; with servility to Macedonian power,
and with love of costly display. How far these two last charges are due
to personal slander it is impossible to say. The only ground for the
first charge is, that he criticised adversely some of Plato's doctrines.

The manuscripts of Aristotle's works passed through many vicissitudes.
At the death of the philosopher they were bequeathed to Theophrastus,
who continued chief of the Peripatetic school for thirty-five years.
Theophrastus left them, with his own works, to a philosophical friend
and pupil, Neleus, who conveyed them from Athens to his residence at
Scepsis, in Asia Minor. About thirty or forty years after the death of
Theophrastus, the kings of Pergamus, to whom the city of Scepsis
belonged, began collecting books to form a library on the Alexandrian
plan. This led the heirs of Neleus to conceal their literary treasures
in a cellar, and there the manuscripts remained for nearly a century
and a half, exposed to injury from damp and worms. At length they were
sold to Apellicon, a resident at Athens, who was attached to the
Peripatetic sect. Many of the manuscripts were imperfect, having become
worm-eaten or illegible. These defects Apellicon attempted to remedy;
but, being a lover of books rather than a philosopher, he performed the
work somewhat unskilfully. When Athens was taken by Sylla, 86 B.C., the
library of Apellicon was transported to Rome. There various literary
Greeks obtained access to it; and, among others, Tyrannion, a grammarian
and friend of Cicero, did good service in the work of correction.
Andronicus of Rhodes afterwards arranged the whole into sections, and
published the manuscripts with a tabulated list.

The three principal works on biology which are extant are: "The History
of Animals;" "On the Parts of Animals;" "On the Generation of Animals."
The other biological works are: "On the Motion of Animals;" "On
Respiration;" "Parva Naturalia;"--a series of essays which are planned
to form an entire work on sense and the sensible.

"The History of Animals" is the largest and most important of
Aristotle's works on biology. It contains a vast amount of information,
not very methodically arranged, and spoiled by the occurrence here and
there of very gross errors. It consists of nine books.

The first book opens with a division of the body into similar and
dissimilar parts. Besides thus differing in their parts, animals also
differ in their mode of life, their actions and dispositions. Thus some
are aquatic, others terrestrial; of the former, some breathe water,
others air, and some neither. Of aquatic animals, some inhabit the sea,
and others rivers, lakes, or marshes. Again, some animals are
locomotive, and others are stationary. Some follow a leader, others act
independently. Various differences are in this way pointed out, and
there is no lack of illustration and detail, but a suspicion is excited
that the generalizations are sometimes based upon insufficient facts.
The book closes with a description of the different parts of the human
body, both internal and external. In speaking of the ear, Aristotle
seems to have been aware of what we now call the Eustachian tube, for he
says, "There is no passage from the ear into the brain, but there is to
the roof of the mouth."[4]

In the second book he passes on to describe the organs of animals. The
animals are dealt with in groups--viviparous and oviparous quadrupeds,
fish, serpents, birds, etc. The ape, elephant, chameleon, and some
others are especially noticed.

The third book continues the description of the internal organs.
References which are made to a diagram by letters, _a_, _b_, _c_, _d_,
show that the work was originally illustrated. At the close of this
book Aristotle has some remarks on milk, and mentions the occasional
appearance of milk in male animals. He speaks of a male goat at Lemnos
which yielded so much that cakes of cheese were made from it. Similar
instances of this phenomenon have been recorded by Humboldt, Burdach,
Geoffroy St. Hilaire, and others.

In the first four chapters of the fourth book the anatomy of the
invertebrata is dealt with, and the accounts given of certain mollusca
and crustacea are very careful and minute. The rest of the book is
devoted to a description of the organs of sense and voice; of sleep, and
the distinctions of sex. The accurate knowledge which Aristotle exhibits
of the anatomy and habits of marine animals, such as the Cephalopoda and
the larger Crustacea, leaves no doubt that he derived it from actual
observation. Professor Owen says, "Respecting the living habits of the
Cephalopoda, Aristotle is more rich in detail than any other zoological
author." What is now spoken of as the _hectocotylization_ of one or more
of the arms of the male cephalopod did not escape Aristotle's eye. And
while he speaks of the teeth and that which serves these animals for a
tongue, it is plain from the context that he means in the one case the
two halves of the parrot-like beak, and in the other the anterior end of
the odontophore.

Books five to seven deal with the subject of generation.

The eighth book contains a variety of details respecting animals, their
food, migrations, hibernation, and diseases; with the influence of
climate and locality upon them.

The ninth book describes the habits and instincts of animals. The
details are interesting; but there is, as usual, very little attempt at
classification. Disjointed statements and sudden digressions occur, the
subjects being treated in the order in which they presented themselves
to the author. Such curious statements as the following are met with:
"The raven is an enemy to the bull and the ass, for it flies round them
and strikes their eyes." "If a person takes a goat by the beard, all the
rest of the herd stand by, as if infatuated, and look at it." "Female
stags are captured by the sound of the pipe and by singing. When two
persons go out to capture them, one shows himself, and either plays upon
a pipe or sings, and the other strikes behind, when the first gives him
the signal." "Swans have the power of song, especially when near the end
of their life; for they then fly out to sea, and some persons sailing
near the coast of Libya have met many of them in the sea singing a
mournful song, and have afterwards seen some of them die." "Of all wild
animals, the elephant is the most tame and gentle; for many of them are
capable of instruction and intelligence, and they have been taught _to
worship the king_."

In the work "On the Parts of Animals," the author considers not only the
phenomena of life exhibited by each species, but also the cause or
causes to which these phenomena are attributable. After a general
introduction, he proceeds to enumerate the three degrees of composition,
viz.:--

 (1) "Composition out of what some call the elements, such as air,
       earth, water, and fire," or "out of the elementary forces, hot
       and cold, solid and fluid, which form the material of all
       compound substances."

 (2) Composition out of these primary substances of the homogeneous
       parts of animals, e.g. blood, fat, marrow, brain, flesh, and
       bone.

 (3) Composition into the heterogeneous parts or organs. These parts he
       describes in detail, considering those belonging to sanguineous
       animals first and most fully.

These divisions correspond roughly to the threefold study of structure
which we nowadays recognize as chemical, histological, and anatomical.

As examples of Aristotle's method of treatment, his descriptions of
blood, the brain, the heart, and the lung may be considered.

Of the _blood_ he says, "What are called fibres are found in the blood
of some animals, but not of all. There are none, for instance, in the
blood of deer and of roes, and for this reason the blood of such
animals as these never coagulates.... Too great an excess of water makes
animals timorous.... Such animals, on the other hand, as have thick and
abundant fibres in their blood are of a more choleric temperament, and
liable to bursts of passion.... Bulls and boars are choleric, for their
blood is exceedingly rich in fibres, and the bull's, at any rate,
coagulates more rapidly than that of any other animal.... If these
fibres are taken out of the blood, the fluid that remains will no longer
coagulate."

From these quotations it will be noted that Aristotle attributed the
coagulum to the presence of fibres, and in this he anticipated
Malpighi's discovery made in the seventeenth century. His remarks on the
proportion of coagulum and serum in different animals, which is enlarged
upon in the "History of Animals,"[5] harmonize with modern observations.
In another of his works[6] he remarks that the blood in certain diseased
conditions will not coagulate. This is known to be the case in cholera,
certain fevers, asphyxia, etc.; and the fact was probably obtained from
Hippocrates. Although Aristotle speaks here of entire absence of
coagulation in the blood of the deer and the roe, in the "History of
Animals" he admits an imperfect coagulation, for he says, "so that their
blood does not coagulate like that of other animals." The animals named
are commonly hunted, and it was probably after they had been hunted to
death that he examined them. Now, it is generally admitted that
coagulation under such circumstances is imperfect and even uncommon. The
statement as to the richness in fibres of the blood of bulls and boars
has been confirmed by some modern investigations, which have shown that
the clot bears a proportion to the strength and ferocity of the animal.
The remarks, however, as to the relative rapidity of coagulation would
appear to be contradicted by later observations, for Thackrah came to
the conclusion that coagulation commenced sooner in small and weak
animals than in strong.

Of the _brain_ Aristotle makes the following among other assertions: "Of
all parts of the body there is none so cold as the brain.... Of all the
fluids of the body it is the one that has the least blood, for, in fact,
it has no blood at all in its proper substance.... That it has no
continuity with the organs of sense is plain from simple inspection, and
still more closely shown by the fact that when it is touched no
sensation is produced.... The brain tempers the heat and seething of the
heart.... In order that it may not itself be absolutely without heat,
blood-vessels from the aorta end in the membrane which surrounds the
brain.... Of all animals man has the largest brain in proportion to his
size: and it is larger in men than in women. This is because the region
of the heart and of the lung is hotter and richer in blood in man than
in any other animal; and in men than in women. This again explains why
man alone of animals stands erect. For the heat, overcoming any opposite
inclination, makes growth take its own line of direction, which is from
the centre of the body upwards.... Man again has more sutures in his
skull than any other animal, and the male more than the female. The
explanation is to be found in the greater size of the brain, which
demands free ventilation proportionate to its bulk.... There is no brain
in the hinder part of the head.... The brain in all animals that have
one is placed in the front part of the head ... because the heart, from
which sensation proceeds, is in the front part of the body."

Although it would perhaps be difficult to find anywhere as many errors
in as few words, yet it should be observed that Aristotle here shows
himself to have been aware of the existence of the membranes of the
brain--the _pia mater_ and the _dura mater_; and elsewhere[7] he says
more explicitly, "Two membranes enclose the brain; that about the skull
is the stronger; the inner membrane is slighter than the outer one." And
further, it should be noted that he describes the latter membrane as a
vascular one. The fact of the brain substance being insensible to
mechanical irritation was known to Aristotle, and may have been learnt
from the practice of Hippocrates. Lastly, it should be remembered
that--though this may have been but a lucky guess on Aristotle's
part--the relative weight of brain to the entire body has been shown,
with few exceptions, to be greater in man than in any other animal.

In describing the _heart_ Aristotle says: "The heart lies about the
centre of the body, but rather in its upper than in its lower half, and
also more in front than behind.... In man it inclines a little towards
the left, so that it may counterbalance the chilliness of that side. It
is hollow, to serve for the reception of the blood; while its wall is
thick, that it may serve to protect the source of heat. For here, and
here alone, in all the viscera, and in fact in all the body, there is
blood without blood-vessels, the blood elsewhere being always contained
within vessels. The heart is the first of all the parts of the body to
be formed, and no sooner is it formed than it contains blood.... For no
sooner is the embryo formed than its heart is seen in motion like a
living creature, and this before any of the other parts. The heart is
abundantly supplied with sinews.... In no animal does the heart contain
a bone, certainly in none of those that we ourselves have inspected,
with the exception of the horse and a certain kind of ox. In animals of
great size the heart has three cavities; in smaller animals it has two;
and in all it has at least one."

It will be observed that here Aristotle so correctly describes the
position of the human heart as to render it probable that he is speaking
from actual inspection; although man is not the only animal in which the
heart is turned towards the left. In contrasting the heart with the
other viscera he appears to have overlooked the existence of the
coronary vessels, and to have imagined that the nutrition of the heart
was effected directly by the blood in its cavities. Although the heart
is not really the first part to appear, the observation of its very
early appearance in the embryo, which he treats more fully elsewhere,[8]
is alone enough to establish his reputation as an original observer. It
is remarkable that Aristotle should have overlooked the presence of the
valves of the heart, the structure and functions of which were fully
investigated within thirty years of his death by the anatomists of the
Alexandrian school. This is the more remarkable, as he calls attention
here, and in the "History of Animals," to the sinews or tendons (νεῦρα)
with which, he says, the heart is supplied, and by which he probably
meant chiefly the _chordæ tendineæ_. The "bone in the heart" of which he
speaks was probably the cruciform ossification which is normally found
in the ox and the stag below the origin of the aorta. It is found in the
horse only in advanced age, or under abnormal conditions. The statement
that the heart contains no more than three chambers has always been
considered as a very gross blunder on the part of Aristotle. Even
Cuvier, who generally lavishes upon the philosopher the most extravagant
praise, sneers at this. Professor Huxley,[9] however, has shown, by a
comparison of several passages from the "History of Animals," that what
we now call the right auricle was regarded by the author as a venous
sinus, as being a part not of the heart, but of the great vein (_i.e._
the superior and the inferior _venæ cavæ_).

Aristotle speaks of the _lung_ as a single organ, sub-divided, but
having a common outlet--the trachea. Elsewhere[10] he says, "Canals from
the heart pass to the lung and divide in the same fashion as the
windpipe does, closely accompanying those from the windpipe through the
whole lung." His theory of respiration, as explained in his treatise on
the subject, is that it tempers the excessive heat produced in the
heart. The lung is compared to a pair of bellows. When the lung is
expanded, air rushes in; when it is contracted, the air is expelled. The
heat from the heart causes the lung to expand--cold air rushes in, the
heat is reduced, the lung collapses, and the air is expelled. The cold
air drawn into the lung reaches the bronchial tubes, and as the vessels
containing hot blood run alongside these tubes, the air cools it and
carries off its superfluous heat. Some of the air which enters the lung
gets from the bronchial tubes into the blood-vessels by transudation,
for there is no direct communication between them; and this air,
penetrating the body, rapidly cools the blood throughout the vessels.
But Aristotle did not consider the "pneuma," which thus reached the
interior of the blood-vessels, to be exactly the same thing as air--it
was "a subtilized and condensed air."[11] And this we now know to be
oxygen.

The treatise "On the Generation of Animals" is an extraordinary
production. "No ancient and few modern works equal it in
comprehensiveness of detail and profound speculative insight. We here
find some of the obscurest problems of biology treated with a mastery
which, when we consider the condition of science at that day, is truly
astounding. That there are many errors, many deficiencies, and not a
little carelessness in the admission of facts, may be readily imagined;
nevertheless at times the work is frequently on a level with, and
occasionally even rises above, the speculations of many advanced
embryologists."[12]

It commences with the statement that the present work is a sequel to
that "On the Parts of Animals;" and first the masculine and feminine
_principles_ are defined. The masculine principle is the origin of all
motion and generation; the feminine principle is the origin of the
material generated. Aristotle's philosophy of nature was teleological,
and the imperfect character of his anatomical knowledge often gives him
occasion to explain particular phenomena by final causes. Thus animals
producing soft-shelled eggs (_e.g._ cartilaginous fish and vipers) are
said to do so because they have so little warmth that the external
surface of the egg cannot be dried.

Among insects, some (_e.g._ grasshopper, cricket, ant, etc.) produce
young in the ordinary way, by the union of the sexes; in other cases
(_e.g._ flies and fleas) this union of the sexes results in the
production of a _skolex_; while others have no parents, nor do they have
congress--such are the ephemera, tipula, and the like. Aristotle
discusses and rejects the theory that the male reproductive element is
derived from every part of the body. He concludes that "instead of
saying that it comes _from_ all parts of the body, we should say that it
goes _to_ them. It is not the nutrient fluid, but that which is _left
over_, which is secreted. Hence the larger animals have fewer young than
the smaller, for by them the consumption of nutrient material will be
larger and the secretion less. Another point to be noticed is, that the
nutrient fluid is universally distributed through the body, but each
secretion has its separate organ.... It is thus intelligible why
children resemble their parents, since that which makes all the parts of
the body, resembles that which is left over as secretion: thus the
hand, or the face, or the whole animal pre-exists in the sperm, though
in an undifferentiated state (ἀδιορίστως); and what each of these is in
actuality (ἐνεργείᾳ), such is the sperm in potentiality (δυνάμει)."

In later times the two great rival theories put forward to account for
the development of the embryo have been--

 (_a_) The theory of Evolution, which makes the embryo pre-existent in
         the germ, and only rendered visible by the unfolding and
         expansion of its organs.

 (_b_) The theory of Epigenesis, which makes the embryo arise, by a
         series of successive differentiations, from a simple
         homogeneous mass into a complex heterogeneous organism.

The above quotation will show how closely Aristotle held to the theory
of Epigenesis; and in another place he says, "Not at once is the animal
a man or a horse, for the end is last attained; and the specific form is
the end of each development."

Spontaneous generation is nowadays rejected by science; but Aristotle
went so far as to believe that insects, molluscs, and even eels, were
spontaneously generated. It is, however, noteworthy, in view of modern
investigations, that he looked upon _putrefying_ matter as the source of
such development.

A chapter of this work is devoted to the consideration of the hereditary
transmission of peculiarities from parent to offspring.

The fifth and last book contains inquiries into the cause of variation
in the colour of the eyes and hair, the abundance of hair, the sleep of
the embryo, sight and hearing, voice and the teeth.

Widely different opinions have been held from time to time of the value
of Aristotle's biological labours. This philosopher's reputation has,
perhaps, suffered most from those who have praised him most. The praise
has often been of such an exaggerated character as to have become
unmeaning, and to have carried with it the impression of insincerity on
the part of the writer. Such are the laudations of Cuvier. To say as he
does, "Alone, in fact, without predecessors, without having borrowed
anything from the centuries which had gone before, since they had
produced nothing enduring, the disciple of Plato discovered and
demonstrated more truths and executed more scientific labours in a life
of sixty-two years than twenty centuries after him were able to do," is
of course to talk nonsense, for the method which Aristotle applied was
that which Hippocrates had used so well before him; and it is evident to
any one that both his predecessors and contemporaries are frequently
laid under contribution by Aristotle, although the authority is rarely,
if ever, stated by him unless he is about to refute the view put
forward. Exaggerated praise of any author has a tendency to excite
depreciation correspondingly unjust and untrue. It has been so in the
case of this great man. In the endeavour to depose him from the
impossible position to which his panegyrists had exalted him, his
detractors have gone to any length. The principal charges brought
against his biological work have been inaccuracy and hasty
generalization. In support of the charge of inaccuracy, some of the
extraordinary statements which are met with in his works are adduced.
"These," Professor Huxley says, "are not so much to be called errors as
stupidities." Some, however, of the inaccuracies alleged against
Aristotle are fancied rather than real. Thus he is charged with having
represented that the arteries contained nothing but air; that the aorta
arose from the right ventricle; that the heart did not beat in any other
animal but man; that reptiles had no blood, etc.; although in reality he
made no one of these assertions. There remain, nevertheless, the gross
misstatements referred to above, and which really do occur. Such, for
instance, as that there is but a single bone in the neck of the lion;
that there are more teeth in male than in female animals; that the mouth
of the dolphin is placed on the under surface of the body; that the back
of the skull is empty, etc. Although these absurdities undoubtedly occur
in Aristotle's works, it by no means follows that he is responsible for
them. Bearing in mind the curious history of the manuscripts of his
treatises, we shall find it far more reasonable to conclude that such
errors crept in during the process of correction and restoration, by men
apparently ignorant of biology, than that (to take only one case) an
observer who had distinguished the cetacea from fishes and had detected
their hidden mammæ, discovered their lungs, and recognized the distinct
character of their bones, should have been so blind as to fancy that the
mouth of these animals was on the under surface of the body.

That Aristotle made hasty generalizations is true; but it was
unavoidable. Biology was in so early a stage that a theory had often of
necessity to be founded on a very slight basis of facts. Yet,
notwithstanding this drawback, so great was the sagacity of this
philosopher, that many of his generalizations, which he himself probably
looked upon as temporary, have held their ground for twenty centuries,
or, having been lost sight of, have been discovered and put forward as
original by modern biologists. Thus "the advantage of physiological
division of labour was first set forth," says Milne-Edwards, "by myself
in 1827;" and yet Aristotle had said[13] that "whenever Nature is able
to provide two separate instruments for two separate uses, without the
one hampering the other, she does so, instead of acting like a
coppersmith, who for cheapness makes a spit-and-a-candlestick in
one.[14] It is only when this is impossible that she uses one organ for
several functions."

In conclusion, we may say that the great Stagirite expounded the true
principles of science, and that when he failed his failure was caused by
lack of materials. His desire for completeness, perhaps, tempted him at
times to fill in gaps with such makeshifts as came to his hand; but no
one knew better than he did that "theories must be abandoned unless
their teachings tally with the indisputable results of observation."[15]


FOOTNOTES:

[3] Pliny, "Natural History," viii. c. 16.

[4] "History of Animals," i. 11.

[5] Bk. iii. 19.

[6] "Meteorology," iv. 7-11.

[7] "History of Animals," i. 16.

[8] "History of Animals," vi. 3.

[9] "On some of the errors attributed to Aristotle."

[10] "History of Animals," i. 17.

[11] See Professor Huxley's article already referred to.

[12] "Aristotle," by G. H. Lewes, p. 325.

[13] "De Part. Anim.," iv. 6.

[14] ὀβελισκολύχνιον.

[15] "De Gener.," iii. 10, quoted by Dr. Ogle.



GALEN.



_GALEN._


Under the Ptolemies a powerful stimulus was given to biological studies
at Alexandria. Scientific knowledge was carried a step or two beyond the
limit reached by Aristotle. Thus Erasistratus and Herophilus thoroughly
investigated the structure and functions of the valves of the heart, and
were the first to recognize the nerves as organs of sensation. But,
unfortunately, no complete record of the interesting work carried on by
these men has come down to our times. The first writer after Aristotle
whose works arrest attention is Caius Plinius Secundus, whose so-called
"Natural History," in thirty-seven volumes, remains to the present day
as a monument of industrious compilation. But, as a biologist properly
so called, Pliny is absolutely without rank, for he lacked that
practical acquaintance with the subject which alone could enable him to
speak with authority. Of information he had an almost inexhaustible
store; of actual knowledge, the result of observation and experience, so
far as biological studies were concerned, he had but little. This was
largely due to the encyclopædic character of the work he undertook; his
mental powers were weighed down by an enormous mass of unarranged and
ill-digested materials. But it was due also to the peculiar bent of
Pliny's mind. He was not, like Aristotle, an original thinker; he was
essentially a student of books, an immensely industrious but not always
judicious compiler. Often his selections from other works prove that he
failed to appreciate the relative importance of the different subjects
to which he made reference. His knowledge of the Greek language appears,
too, to have been defective, for he gives at times the wrong Latin names
to objects described by his Greek authorities. To these defects must be
added his marvellous readiness to believe any statement, provided only
that it was uncommon; while, on the other hand, he showed an
indefensible scepticism in regard to what was really deserving of
attention. The chief value of his work consists in the historical and
chronological notes of the progress of some of the subjects of which he
treats--fragments of writings which would otherwise be lost to us. Pliny
was killed in the destruction of Pompeii, A.D. 79.

Claudius Galenus was born at Pergamus, in Asia Minor, in the hundred and
thirty-first year of the Christian era. Few writers ever exercised for
so long a time such an undisputed sway over the opinions of mankind as
did this wonderful man. His authority was estimated at a much higher
rate than that of all the biological writers combined who flourished
during a period of more than twelve centuries, and it was often
considered a sufficient argument against a hypothesis, or even an
alleged matter of fact, that it was contrary to Galen.

Endowed by nature with a penetrating genius and a mind of restless
energy, he was eminently qualified to profit by a comprehensive and
liberal education. And such he received. His father, Nicon, an
architect, was a man of learning and ability--a distinguished
mathematician and an astronomer--and seems to have devoted much time and
care to the education of his son. The youth appears to have studied
philosophy successively in the schools of the Stoics, Academics,
Peripatetics, and Epicureans, without attaching himself exclusively to
any one of these, and to have taken from each what he thought to be the
most essential parts of their system, rejecting, however, altogether the
tenets of the Epicureans. At the age of twenty-one, on the death of his
father, he went to Smyrna to continue the study of medicine, to which he
had now devoted himself. After leaving this place and having travelled
extensively, he took up his residence at Alexandria, which was then the
most favourable spot for the pursuit of medical studies. Here he is said
to have remained until he was twenty-eight years of age, when his
reputation secured his appointment, in his native city of Pergamus, to
the office of physician in charge of the athletes in the gymnasia
situated within the precincts of the temple of Æsculapius. For five or
six years he lived in Pergamus, and then a revolt compelled him to leave
his native town. The advantages offered by Rome led him to remove
thither and take up his residence in the capital of the world. Here his
skill, sagacity, and knowledge soon brought him into notice, and excited
the jealousy of the Roman doctors, which was still further increased by
some wonderful cures the young Greek physician succeeded in effecting.
Possibly it was owing to the ill feeling shown to Galen that, on the
outbreak of an epidemic a year afterwards, he left the imperial city and
proceeded to Brindisi, and embarked for Greece. It was his intention to
devote his time to the study of natural history, and for this purpose he
visited Cyprus, Palestine, and Lemnos. While at the last-named place,
however, he was suddenly summoned to Aquileia to meet the Emperors
Marcus Aurelius and Lucius Verus. He travelled through Thrace and
Macedonia on foot, met the imperial personages, and prepared for them a
medicine, for which he seems to have been famous, and which is spoken of
as the _theriac_. It was probably some combination of opium with various
aromatics and stimulants, for antidotes of many different kinds were
habitually taken by the Romans to preserve them from the ill effects of
poison and of the bites of venomous animals.[16]

With the Emperor M. Aurelius he returned to Rome, and became afterwards
doctor to the young Emperor Commodus. He did not, however, remain for a
long period at Rome, and probably passed the greater part of the rest of
his life in his native country.

Although the date of his death is not positively known, yet it appears
from a passage[17] in his writings that he was living in the reign of
Septimius Severus; and Suidas seems to have reason for asserting that he
reached his seventieth year.

Galen's writings represent the common depository of the anatomical
knowledge of the day; what he had learnt from many teachers, rather than
the results of his own personal research. Roughly speaking, they deal
with the following subjects: Anatomy and Physiology, Dietetics and
Hygiene, Pathology, Diagnosis and Semeiology, Pharmacy and Materia
Medica, Therapeutics.

The only works of this voluminous writer at which we can here glance are
those dealing with Anatomy and Physiology. These exhibit numerous
illustrations of Galen's familiarity with practical anatomy, although it
was most likely comparative rather than human anatomy at which he
especially worked. Indeed, he seems to have had but few opportunities of
carrying on human dissections, for he thinks himself happy in having
been able to examine at Alexandria two human skeletons; and he
recommends the dissection of monkeys because of their exact resemblance
to man. To this disadvantage may, perhaps, be attributed the readiness,
which sometimes appears, to assume identity of organization between man
and the brutes. Thus, because in certain animals he found a double
biliary duct, he concluded the same to be the case in man, and in one
instance he proceeded to deduce the cause of disease from this erroneous
assumption.

He supposed that there were three modes of existence in man, namely--

 (_a_) The nutritive, which was common to all animals and plants, of
         which the liver was the source.

 (_b_) The vital, of which the heart was the source.

 (_c_) The rational, of which the brain was the source.

Again, he considered that the animal economy possessed four natural
powers--

 (1) The attractive.

 (2) The alterative or assimilative.

 (3) The retentive or digestive.

 (4) The expulsive.

Like his predecessors, he asserted that there were four humours, namely,
blood, yellow bile, black bile, and aqueous serum. He held that it was
the office of the liver to complete the process of sanguification
commenced in the stomach, and that during this process the yellow bile
was attracted by the branches of the hepatic duct and gall-bladder; the
black bile being attracted by the spleen, and the aqueous humour by the
two kidneys; while the liver itself retained the pure blood, which was
afterwards attracted by the heart through the vena cava, by whose
ramifications it was distributed to the various parts of the body.

Following Aristotle especially, he regarded hair, nails, arteries,
veins, cartilage, bone, ligament, membranes, glands, fat, and muscle as
the simplest constituents of the body, formed immediately from the
blood, and perfectly homogeneous in character. The organic members,
_e.g._ lungs, liver, etc., he looked upon as formed of several of the
foregoing simple parts.

The osteology contained in Galen's works is nearly as perfect as that of
the present day. He correctly names and describes the bones and sutures
of the cranium; notices the quadrilateral shape of the parietals, the
peculiar situation and shape of the sphenoid, and the form and character
of the ethmoid, malar, maxillary, and nasal bones. He divides the
vertebral columns into cervical, dorsal, and lumbar portions.

With regard to the nervous system, he taught that the nerves of the
senses are distinct from those which impart the power of motion to
muscles--that the former are derived from the anterior parts of the
brain, while the latter arise from the posterior portion, or from the
spinal cord. He maintained that the nerves of the finer senses are
formed of matter too soft to be the vehicles of muscular motion;
whereas, on the other hand, the nerves of motion are too hard to be
susceptible of fine sensibility. His description of the method of
demonstrating the different parts of the brain by dissection is very
interesting, and, like his references to various instruments and
contrivances, proves him to have been a practical and experienced
anatomist.

In his description of the organs and process of nutrition, absorption by
the veins of the stomach is correctly noticed, and the union of the
mesenteric veins into one common _vena portæ_ is pointed out. The
communications between the ramifications of the vena portæ and of the
proper veins of the liver are supposed by Galen to be effected by means
of anastomosing pores or channels. Although it is evident that Galen was
ignorant of the true absorbent system, yet he appears to have been aware
of the _lacteals_; for he says that in addition to those mesenteric
veins which by their union form the vena portæ, there are visible in
every part of the mesentery other veins, proceeding also from the
intestines, which terminate in glands; and he supposes that these veins
are intended for the nourishment of the intestines themselves. Some of
Galen's contemporaries asserted that upon exposing the mesentery of a
sucking animal several small vessels were seen filled _first_ with air,
and _afterwards_ with milk. They had, doubtless, mistaken colourless
lymph for air; but Galen ridicules both assertions, and thereby shows
that he had not examined the contents of the lacteals. This is somewhat
remarkable, because as a rule he omitted no opportunity of determining
with certainty, by vivisection and experiments on living animals, the
uses of the various parts of the body. As an illustration of this, we
have his correct statement, established by experiment, that the pylorus
acts as a valve _only_ during the process of digestion, and that it is
relaxed when digestion is completed.

He recognizes that the flesh of the heart is somewhat different to that
of the muscles of voluntary motion. Its fibres are described as being
arranged in longitudinal and transverse bundles; the former by their
contractions shortening the organ, the latter compressing and narrowing
it. Such statements show that he regarded the heart as essentially
muscular. He thought, however, that it was entirely destitute of nerves.
Although he admitted that possibly it had one small branch derived from
the _nervus vagus_ sent to it, yet he entirely overlooked the great
nervous plexus surrounding the roots of the blood-vessels, from which
branches proceed in company with the branches of the coronary arteries
and veins, and penetrate the muscular substance of the ventricles. He
endeavoured to prove, by experiment, observation, and reasoning, that
the arteries as well as the veins contained blood, and in this
connection he tells an amusing story. A certain teacher of anatomy, who
had declared that the aorta contained no blood, was earnestly desired by
his pupils, who were ardent disciples of Galen, to exhibit the requisite
demonstration, they themselves offering animals for the experiment. He,
however, after various subterfuges, declined, until they promised to
give him a suitable remuneration, which they raised by subscription
among themselves to the amount of a thousand drachmæ (perhaps £30). The
professor, being thus compelled to commence the experiment, totally
failed in his attempt to cut down upon the aorta, to the no small
amusement of his pupils, who, thereupon taking up the experiment
themselves, made an opening into the thorax in the way in which they had
been instructed by Galen, passed one ligature round the aorta at the
part where it attaches itself to the spine, and another at its origin,
and then, by opening the intervening portion of the artery, showed that
blood was contained in it.

The arteries, Galen thought, possessed a pulsative and attractive power
of their own, independently of the heart, the moment of their dilatation
being the moment of their activity. They, in fact, _drew_ their charge
from the heart, as the heart by its diastole _drew_ its charge from the
vena cava and the pulmonary vein. The pulse of the arteries, he also
thought, was propagated by their coats, not by the wave of blood thrown
into them by the heart. He taught that at every systole of the arteries
a certain portion of their contents was discharged at their extremities,
namely, by the exhalents and secretory vessels. Though he demonstrated
the anastomosis of arteries and veins, he nowhere hints his belief that
the contents of the former pass into the latter, to be conveyed back to
the heart, and from it to be again diffused over the body. He made a
near approach to the Harveian theory of the circulation, as Harvey
himself admits in his "De Motu Cordis;"[18] but the grand point of
difference between Galen and Harvey is the question whether or not, at
every systole of the left ventricle, more blood is thrown out than is
expended on exhalation, secretion, and nutrition. Upon this point Galen
held the negative, and Harvey, as we all know, the affirmative.

The famous Asclepiads held that respiration was for the generation of
the soul itself, breath and life being thus considered to be identical.
Hippocrates thought it was for the nutrition and refrigeration of the
innate heat, Aristotle for its ventilation, Erasistratus for the
filling of the arteries with spirits. All these opinions are discussed
and commented upon by Galen, who determines the purposes of respiration
to be (1) to preserve the animal heat; (2) to evacuate from the blood
the products of combustion.

He conjectured that there was in atmospheric air not only a quality
friendly to the vital spirit, but also a quality inimical to it, which
conjecture he drew from observation of the various phenomena
accompanying the support and the extinction of flame; and he says that
if we could find out why flame is extinguished by absence of the air, we
might then know the nature of that substance which imparts warmth to the
blood during the process of respiration.

On another occasion he says that it is evidently the _quality_ and not
the _quantity_ of the air which is necessary to life. He further shows
that he recognized the analogy between respiration and combustion, by
comparing the lungs to a lamp, the heart to its wick, the blood to the
oil, and the animal heat to the flame.

From certain observations in various parts of his works, it appears
that, although ignorant of the doctrine of atmospheric pressure, he was
acquainted with some of its practical effects. Thus, he says, if you put
one end of an open tube under water and suck out the air with the other
end, you will draw up water into the mouth, and that it is in this way
that infants extract the milk from the mother's breast.

Again, Erasistratus supposed that the vapour of charcoal and of certain
pits and wells was fatal to life because _lighter_ than common air, but
Galen maintained it to be _heavier_.

He describes two kinds of respiration, one by the mouths of the arteries
of the lungs, and one by the mouths of the arteries of the skin. In each
case, he says, the surrounding air is drawn into the vessels during
their diastole, for the purpose of cooling the blood, and during their
systole the fuliginous particles derived from the blood and other fluids
of the body are forced out.

He considers the diaphragm to be the principal muscle of respiration,
but he makes a clear distinction between ordinary respiration, which he
calls a natural and involuntary effort, and that deliberate and forced
respiration which is obedient to the will; and he says that there are
different muscles for the two purposes. Elsewhere he particularly points
out the two sets of intercostal muscles and their mode of action, of
which, before his time, he asserts that anatomists were ignorant.

He describes various effects produced on respiration and on the voice by
the division of those nerves which are connected with the thorax; and
shows particularly the effect of dividing the recurrent branch of his
sixth pair of cerebral nerves (the pneumogastric of modern anatomy). He
explains how it happens that after division of the spinal cord, provided
that division be _beneath_ the lower termination of the neck, the
diaphragm will still continue to act--in consequence, namely, of the
origin of the phrenic nerve being _above_ the lower termination of the
neck.

Before the time of Galen the medical profession was divided into several
sects, _e.g._ Dogmatici, Empirici, Eclectici, Pneumatici, and
Episynthetici, who were always disputing with one another. After his
time all sects seem to have merged in his followers. The subsequent
Greek and Roman biological writers were mere compilers from his works,
and as soon as his writings were translated into Arabic they were at
once adopted throughout the East to the exclusion of all others. He
remained paramount throughout the civilized world until within the last
three hundred years. In the records of the College of Physicians of
England we read that Dr. Geynes was cited before the college in 1559 for
impugning the infallibility of Galen, and was only admitted again into
the privileges of his fellowship on acknowledgment of his error, and
humble recantation signed with his own hand. Kurt Sprengel has well said
that "if the physicians who remained so faithfully attached to Galen's
system had inherited his penetrating mind, his observing glance, and his
depth, the art of healing would have approached the limit of perfection
before all the other sciences; but it was written in the book of
destiny that mind and reason were to bend under the yoke of superstition
and barbarism, and were only to emerge after centuries of lethargic
sleep."


FOOTNOTES:

[16] Hence the name θηρίακαι.

[17] "De Antidotis," i. 13, vol. xiv. p. 65, Kuhn.

[18] "Ex ipsius etiam Galeni verbis hanc veritatem confirmari posse,
scilicet: non solum posse sanguinem e vena arteriosa in arteriam venosam
et inde in sinistrum ventriculum cordis, et postea in arterias
transmitti."--"De Motu Cordis," cap. vii.



VESALIUS.



_VESALIUS._


The authority of Galen, at once a despotism and a religion, was scarcely
ever called in question until the sixteenth century. No attempt worth
recording was made during thirteen hundred years to extend the boundary
of scientific knowledge in anatomy and physiology. It is true that the
scholastic philosopher, Albertus Magnus, who was for a short time
(1260-1262) Bishop of Ratisbon, in the middle of the thirteenth century
wrote a "History of Animals," which was a remarkable production for the
age in which he lived; although Sir Thomas Browne, in his famous
"Enquiries into Common Errors," speaks of these "Tractates" as requiring
to be received with caution, adding as regards Albertus that "he was a
man who much advanced these opinions by the authoritie of his name, and
delivered most conceits, with strickt enquirie into few."

As regards human anatomy, it was considered, during the Middle Ages, to
be impiety to touch with a scalpel "the dead image of God," as man's
body was called. Mundinus, the professor of medicine at Bologna from
1315 to 1318, was the first to attempt any such thing. He exhibited the
public dissection of three bodies, but by this created so great a
scandal that he gave up the practice, and contented himself with
publishing a work, "De Anatome," which formed a sort of commentary on
Galen. This work, with additions, continued to be the text-book of the
schools until the time of Vesalius, who founded the study of anatomy as
nowadays pursued.

Andreas Vesalius was born at Brussels, on the last day of the year 1514,
of a family which for several generations had been eminent for medical
attainments. He was sent as a boy to Louvain, where he spent the greater
part of his leisure in researches into the mechanism of the lower
animals. He was a born dissector, who, after careful examination, in his
early days, of rats, moles, dogs, cats, monkeys, and the like, came, in
after-life, to be dissatisfied with any less knowledge of the anatomy of
man.

He acquired great proficiency in the scholarship of the day. Indeed the
Latin, in which he afterwards wrote his great work, is so singularly
pure that one of his detractors pretended that Vesalius must have got
some good scholar to write the Latin for him. Latin was not the only
language in which he was proficient; he added Greek and Arabic to his
other accomplishments, and this for the purpose of reading the great
biological works in the languages in which they were originally written.
From Louvain the youth went to Paris, where he studied anatomy under a
most distinguished physician, Sylvius. It was the practice of that
illustrious professor to read to his class Galen on the "Use of Parts,"
omitting nearly all the sections where exact knowledge of anatomical
detail was necessary. Sometimes an attempt was made to illustrate the
lecture by the dissection of a dog, but such illustration more often
exposed the professor's ignorance than it added to the student's
knowledge. Indirectly, however, it did good, for whenever Sylvius, after
having tried in vain to demonstrate some muscle, or nerve, or vein, left
the room, his pupil Vesalius slipped down to the table, dissected out
the part with great neatness, and triumphantly called the professor's
attention to it on his return.

Besides studying under Sylvius, Vesalius had for his teacher at Paris
the famous Winter, of Andernach, who was physician to Francis I. This
learned man, in a work published three years after this period, speaks
of Vesalius as a youth of great promise. At the age of nineteen Vesalius
returned to Louvain; and here for the first time he openly demonstrated
from the human subject. In this connection a somewhat ghastly story is
told, which serves to show the intensity of the enthusiasm with which
our anatomist was inspired. On a certain evening it chanced that
Vesalius, in company with a friend, had rambled out of the gates of
Louvain to a spot where the bodies of executed criminals were wont to
be exposed. A noted robber had been executed. His body had been chained
to a stake and slowly roasted; and the birds had so entirely stripped
the bones of every vestige of flesh, that a perfect skeleton, complete
and clean, was suspended before the eyes of the anatomist, who had been
striving hitherto to piece together such a thing out of the bones of
many people, gathered as occasion offered. Mounting upon the shoulder of
his friend, Vesalius ascended the charred stake and forcibly tore away
the limbs, leaving only the trunk, which was securely bound by iron
chains. With these stolen bones under their clothes the two youths
returned to Louvain. In the night, however, and alone, the sturdy
Vesalius found his way again to the place--which to most men, at any
rate in those times, would have been associated with unspeakable
horrors--and there, by sheer force, wrenched away the trunk, and buried
it. Then leisurely and carefully, day after day, he smuggled through the
city gates bone after bone. Afterwards, when he had set up the perfect
skeleton in his own house, he did not hesitate to demonstrate from it.
But such an act of daring plunder could not escape detection, and he was
banished from Louvain for the offence. This story is here quoted only to
show the extraordinary physical and moral courage which the anatomist
possessed; which upheld him through toils, dangers, and disgusts; and by
which he was strengthened to carry on, even in a cruel and
superstitious age, and placed, as he was, on the very threshold of the
Inquisition, a work at all times repulsive to flesh and blood.

After serving for a short time as a surgeon in the army of the Emperor
Charles V., Vesalius went to Italy, where he at once attracted the
attention of the most learned men, and became, at the age of twenty-two,
Professor of Anatomy at the University of Padua. This was the first
purely anatomical professorship that had been established out of the
funds of any university. For seven years he held the office, and he was
at the same time professor at Bologna and at Pisa. During these years
his lectures were always well attended, for they were a striking
innovation on the tameness of conventional routine. In each university
the services of the professor were confined to a short course of
demonstrations, so that his duties were complete when he had spent,
during the winter, a few weeks at each of the three towns in succession.
He then returned to Venice, which he appears to have made his
head-quarters. At this city, as well as at Pisa, special facilities were
offered to the professor for obtaining bodies either of condemned
criminals or others. At Padua and Bologna the enthusiasm of the
students, who became resurrectionists on their teacher's behalf, kept
the lecture-table supplied with specimens. They were in the habit of
watching all the symptoms in men dying of a fatal malady, and noting
where, after death, such men were buried. The seclusion of the graveyard
was then invaded, and the corpse secretly conveyed by Andreas to his
chamber, and concealed sometimes in his own bed. A diligent search was
at once made to determine accurately the cause of death. This pitiless
zeal for correct details in anatomy, associated as it was with
indefatigable practice in physic, appeared to Vesalius, as it does to
his successors of to-day, to be the only satisfactory method of
acquiring that knowledge which is essential to a doctor. Thus it was
that he, who at the age of twenty-two was able to name, with his eyes
blindfolded, any human bone put into his hand, who was deeply versed in
comparative anatomy, and had more accurate knowledge of the human frame
than any graybeard of the time, enjoyed afterwards a reputation as a
physician which was unbounded. One illustration of his sagacity in
diagnosis will suffice. A patient of two famous court physicians at
Madrid had a big and wonderful tumour on the loins. It would have been
easily recognized in these days as an aneurismal tumour, but it greatly
puzzled the two doctors. Vesalius was therefore consulted, and said,
"There is a blood-vessel dilated; that tumour is full of blood." They
were surprised at such a strange opinion; but the man died, the tumour
was opened; blood was actually found in it, and we are told _in
admirationem rapti fuère omnes_.

It was not until after Vesalius had been three years professor that he
began to distrust the infallibility of Galen's anatomical teaching.
Constant practical experience in dissection, both human and comparative,
slowly convinced him that--great anatomist as the "divus homo" had
undoubtedly been--his statements were not only incomplete, but often
wrong; further, that Galen very rarely wrote from actual inspection of
the human subject, but based his teaching on a belief that the structure
of a monkey was exactly similar to that of a man. With this conviction
established, Vesalius proceeded to note with great care all the
discrepancies between the text of Galen and the actual parts which it
endeavoured to describe, and in this way a volume of considerable
thickness was soon formed, consisting entirely of annotations upon
Galen. The generally received authorities being thus found to be
unreliable, it became necessary in the next place to collect and arrange
the fundamental facts of anatomy upon a new and sounder basis. To this
task Vesalius, at the age of twenty-five, devoted himself, and began his
famous work on the "Fabric of the Human Body." Owing possibly to the
good fortune of his family, and to the income which he derived from his
professorships, Andreas was able to secure for his work the aid of some
of the best artists of the day. To Jean Calcar, one of the ablest of the
pupils of Titian, are due the splendid anatomical plates which
illustrate the "Corporis Humani Fabrica," and which are incomparably
better than those of any work which preceded it. To him most likely is
due also the woodcut which adorns the first page, and which represents
the young Vesalius, wearing professor's robes, standing at a
lecture-table and pointing out, from a robust subject that lies before
him, the inner secrets of the human body; while the tiers of benches
that surround the professor are completely crowded with grave doctors
struggling to see, even climbing upon the railings to do so.

But throughout the work the plates are used simply to illustrate and
elucidate the text, and the information furnished in the latter is
minute and accurate, and stated in well-polished Latin. As the author
proceeds, he finds it necessary to disagree with Galen, and the reasons
for this disagreement are given. The inevitable result follows that
Vesalius is placed at issue not only with "the divine man," but also
with all those who for thirteen centuries had unquestioningly followed
him. Such a result Vesalius must have foreseen. It was not, therefore, a
great surprise to him, perhaps, to receive, soon after the publication
of his work, a violent onslaught from his old master Sylvius. He simply
replied to it by a letter full of respect and friendly feeling,
inquiring wherein he had been guilty of error. The answer he got was
that he must show proper respect for Galen, if he wished to be regarded
as a friend of Sylvius.

In 1546, three years after the publication of his great work, Andreas
was summoned to Ratisbon to exercise his skill upon the emperor, and
from that date he was ranked among the court physicians. In the same
year, 1546, in a long letter, entitled "De usu Radicis Chinæ," he not
only treats of the medicine by which the emperor's health had been
restored, but he vindicates his teaching against his assailants, and
again gives cumulative proof of the fact that Galen had dissected only
brutes.

It was the practice of Vesalius, while he was professor in Italy, to
issue a public notice the day before each demonstration, stating the
time at which it would take place, and inviting all who decried his
errors to attend and make their own dissections from his subject, and
confound him openly. It does not appear that any one was rash enough
ever to accept the challenge; yet, although the majority of the young
men were on the side of Vesalius, the older teachers continued to regard
him as a heretic, and in 1551 Sylvius published a bitterly personal
attack. It was nothing to him that the results of actual dissection were
against him--he even went so far as to assert that the men of his time
were constructed somewhat differently to those of the time of Galen!
Thus, to the proof that Vesalius gave that the carpal bones were not
absolutely without marrow, as Galen had asserted, Sylvius replied that
the bones were harder and more solid among the ancients, and were, in
consequence, destitute of medullary substance. Again, when Vesalius
showed that Galen was wrong in describing the human femur and humerus as
greatly curved, Sylvius explained the discrepancy by saying that the
wearing of narrow garments by the moderns had straightened the limbs.

Through these attacks, however, the writings of Vesalius fell into
somewhat bad odour in the court; for in that very superstitious age
there was a kind of vague dread felt of reading the works of a man
against whom such serious charges of arrogance and impiety were brought.
And so it came about that when he received the summons to take up his
residence permanently at Madrid, and the orthodoxy of the day seemed for
the moment to triumph, in a fit of proud indignation, he burned all his
manuscripts; destroying a huge volume of annotations upon Galen; a whole
book of medical formulæ; many original notes on drugs; the copy of Galen
from which he lectured, and which was covered with marginal notes of new
observations that had occurred to him while demonstrating; and the
paraphrases of the books of Rhases, in which the knowledge of the
Arabian was collated with that of the Greeks and others. The produce of
the labour of many years was thus reduced to ashes in a short fit of
passion, and from this time Vesalius lived no more for controversy or
study. He gave himself up to pleasure and the pursuit of wealth, resting
on his reputation and degenerating into a mere courtier. As a
practitioner he was held in high esteem. When the life of Don Carlos,
Philip's son, was despaired of, it was Vesalius who was called in, and
who, seeing that the surgeons had bound up the wound in the head so
tightly that an abscess had formed, promptly brought relief to the
patient by cutting into the pericranium. The cure of the prince,
however, was attributed by the court to the intercession of St. Diego,
and it is possible that on the subject of this alleged miraculous
recovery Vesalius may have expressed his opinion rather more strongly
than it was safe for a Netherlander to do. At any rate, the priests
always looked upon him with dislike and suspicion, and at length they
and the other enemies of the great anatomist had their revenge.

A young Spanish nobleman had died, and Vesalius, who had attended him,
obtained permission to ascertain, if possible, by a post-mortem
examination, the cause of death. On opening the body, the heart was
said--by the bystanders--to beat; and a charge, not merely of murder,
but of impiety also, was brought against Vesalius. It was hoped by his
persecutors that the latter charge would be brought before the
Inquisition, and result in more rigorous punishment than any that would
be inflicted by the judges of the common law. The King of Spain,
however, interfered and saved him, on condition that he should make a
pilgrimage to the Holy Land. Accordingly he set out from Madrid for
Venice, and thence to Cyprus, from which place he went on to Jerusalem,
and was returning, not to Madrid, but to Padua, where the professorship
of physic had been offered him, when he suffered shipwreck on the island
of Zante, and there perished miserably of hunger and grief, on October
15, 1564, before he had reached the age of fifty. His body was found by
a travelling goldsmith, who recognized, notwithstanding their starved
outlines, the features of the renowned anatomist, and respectfully
buried his remains and raised a statue to his memory.

Two of the works of this great man have been already referred to,
namely: "De Corporis Humani Fabrica;" "De usu Radicis Chinæ." Besides
these the following have appeared: "Examen Observationum Gabrielis
Fallopii;" "Gabrielis Cunei Examen, Apologiæ Francisci Putei pro Galeno
in Anatome;" a great work on Surgery in seven books.

With respect to the last of these, it may be sufficient to remark that
there is every reason to believe that the name of the famous anatomist
was stolen after his death to give value to the production, which was
compiled and published by a Venetian named Bogarucci; and that Vesalius
is not responsible for the contents.

The other works are undoubtedly genuine. In 1562 Andreas seems to have
been roused for a short time from the lethargy into which he had sunk,
by an attack from Franciscus Puteus; for to this attack a reply
appeared--from a writer calling himself Gabriel Cuneus--which has always
been attributed by the most competent authorities to Vesalius himself.
In this rather long work, covering as it does more than fifty pages in
the folio edition, the views of Vesalius, which are at variance with
Galen, are gone through _seriatim_ and defended.

In 1561 Fallopius, who had studied under Vesalius, published his
"Anatomical Observations," containing several points in which he had
extended the knowledge of anatomy beyond the limits reached by his
master. He had taught publicly for thirteen years at Ferrara, and had
presided for eight years over an anatomical school, so that he was no
novice in the field of biology. Yet so completely had Vesalius lost the
philosophic temperament that he regarded this publication as an
infringement of his rights, and in this spirit wrote an "Examen
Observationum Fallopii," in which he decried the friend who had made
improvements on himself, as he had been decried for his improvements on
Galen. The manuscript of this work, finished at the end of December,
1561, was committed by the author to the care of Paulus Teupulus of
Venice, orator to the King of Spain, who was to give it to Fallopius.
The orator, however, did not reach Padua until after the death of
Fallopius, and he consequently retained the document until Vesalius, on
his way to Jerusalem, took possession of it, and caused it to be
published without delay. It appeared at Venice in 1564.[19]

The letter on the China root--a plant we know nowadays as
sarsaparilla--by the use of which the emperor's recovery was effected,
has been already referred to. It was addressed to the anatomist's
friend, Joachim Roelants. Very little space, however, is taken up with a
description of the medicine which gives title to the letter. Something
certainly is said of the history and nature of the plant, the
preparation of the decoction and its effects; but the writer soon
introduces the subject which was at that time of very vital importance
to him, namely, his position with regard to the statements of Galen and
his followers. He collects together various assertions of the Greek
anatomist, on the bones, the muscles and ligaments, the relations of
veins and arteries, the nerves, the character of the peritoneum, the
organs of the thorax, the skull and its contents, etc., and shows from
each and all of these that reference had not been made to the human
subject, and that therefore the statements were unreliable.

To the work on the "Fabric of the Human Body" we have already alluded,
as well as to the causes which led to its being written. More than half
of this great treatise is occupied with a minute description of the
build of the human body--its bones, cartilages, ligaments, and muscles.
It may have been owing to the thorough acquaintance which Vesalius
showed with these parts that his detractors pretended afterwards that he
only understood superficial injuries. But other branches of anatomy are
fully dealt with. The veins and arteries are described in the third
book, and the nerves in the fourth; the organs of nutrition and
reproduction are treated of in the next; while the remaining two books
are devoted to descriptions of the heart and brain.

Vesalius gives a good account of the sphenoid bone, with its large and
small wings and its pterygoid processes; and he accurately describes the
vestibule in the interior of the temporal bone. He shows the sternum to
consist, in the adult, of three parts and the sacrum of five or six. He
discovered the valve which guards the _foramen ovale_ in the fœtus; and
he not only verified the observation of Etienne as to the valve-like
fold guarding the entrance of each hepatic vein into the inferior vena
cava, but he also fully described the _vena azygos_. He observed, too,
the canal which passes in the fœtus between the umbilical vein and vena
cava, and which has since been known as the _ductus venosus_. He was the
first to study and describe the mediastinum, correcting the error of the
ancients, who believed that this duplicature of the pleura contained a
portion of the lungs. He described the omentum and its connections with
the stomach, the spleen, and the colon; and he enunciated the first
correct views of the structure of the pylorus, noticing at the same time
the small size of the cæcal appendix in man. His account of the anatomy
of the brain is fuller than that of any of his predecessors, but he does
not appear to have well understood the inferior recesses, and his
description of the nerves is confused by regarding the optic as the
first pair, the third as the fifth, and the fifth as the seventh. The
ancients believed the optic nerve to be hollow for the conveyance of the
visual spirit, but Vesalius showed that no such tube existed. He
observed the elevation and depression of the brain during respiration,
but being ignorant of the circulation of the blood, he wrongly explained
the phenomenon.

Exclusively an anatomist, he makes but brief references in his great
work to the functions of the organs which he describes. Where he differs
from Galen on these matters he does so apologetically. He follows him in
regarding the heart as the seat of the emotions and passions--the
hottest of all the viscera and source of heat of the whole body;
although he does not, as Aristotle did, look upon the heart as giving
rise to the nerves. He considers the heart to be in ceaseless motion,
alternately dilating and contracting, but the diastole is in his opinion
the influential act of the organ. He knows that eminences or projections
are present in the veins, and indeed speaks of them as being analogous
to the valves of the heart, but he denies to them the office of valves.
To him the motion of the blood was of a to-and-fro kind, and valves in
the veins acting as such would have interfered with anything of the
sort. He expresses clearly the idea, that was entertained in the old
physiology, of the attractions exerted by the various parts of the body
for the blood; and especially that of the veins and heart for the blood
itself. "The right sinus of the heart," he says, "attracts blood from
the vena cava, and the left attracts air from the lungs through the
_arteria venalis_ (pulmonary vein), the blood itself being attracted by
the veins in general, the vital spirit by the arteries." Again, he
speaks of the blood filtering through the septum between the ventricles
as if through a sieve, although he knows perfectly well from his
dissection that the septum is quite impervious.

It will thus be seen that the physiological teaching of Galen was left
undisturbed by Vesalius.


FOOTNOTES:

[19] See Professor Morley's article on "Anatomy in Long Clothes," in
_Fraser's Magazine_, 1853, from which most of the facts in this sketch
have been taken.



HARVEY.



_HARVEY._


The importance of Harvey's discovery of the circulation of the blood can
only be properly estimated by bearing in mind what was done by his
predecessors in the same field of inquiry. Aristotle had taught that in
man and in the higher brutes the blood was elaborated from the food in
the liver, conveyed to the heart, and thence distributed by it through
the veins to the whole body. Erasistratus and Herophilus held that,
while the veins carried blood from the heart to the members, the
arteries carried a subtle kind of air or spirit. Galen discovered that
the arteries were not merely air-pipes, but that they contained blood as
well as vital air or spirit. Sylvius, the teacher of Vesalius, was aware
of the presence of valves in the veins; and Fabricius, Harvey's teacher
at Padua, described them much more accurately than Sylvius had done; but
neither of these men had a true idea of the significance of the
structures of which they wrote. Servetus, the friend and contemporary of
Vesalius, writing in 1533, correctly described the course of the lesser
circulation in the following words: "This communication (_i.e._ between
the right and left sides of the heart) does not take place through the
partition of the heart, as is generally believed; but by another
admirable contrivance, whereby from the right ventricle the subtle blood
is agitated in a lengthened course through the lungs, wherein prepared,
it becomes of a crimson colour, and from the vena arterialis (pulmonary
artery) is transferred into the arteria venalis (pulmonary vein).
Mingled with the inspired air in the arteria venalis, freed by
respiration from fuliginous matter, and become a suitable home of the
vital spirit, it is attracted at length into the left ventricle of the
heart by the diastole of the organ." But when Servetus comes to speak of
the systemic circulation, what he has to say is as old as Galen.

The opinions, therefore, on the subject of the blood and its
distribution which were prevalent at the end of the sixteenth century
prove--

 (1) That although the blood was not regarded as stagnant, yet its
       circulation, such as is nowadays recognized, was unknown;

 (2) That one kind of blood was thought to flow from the liver to the
       right ventricle, and thence to the lungs and general system by
       the veins, while another kind flowed from the left ventricle to
       the lungs and general system by the arteries;

 (3) That the septum of the heart was regarded as admitting of the
       passage of blood directly from the right to the left side;

 (4) That there was no conception of the functions of the heart as the
       motor power of the movement of the blood, for biologists of that
       day doubted whether the substance of the heart were really
       muscular; they supposed the pulsations to be due to expansion of
       the spirits it contained; they believed the only dynamic effect
       which it had on the blood to be that of sucking it in during its
       active diastole, and they supposed the chief use of its constant
       movements to be the due mixture of blood and spirits.

This was the state of knowledge before Harvey's time. By his great work
he established--

 (1) That the blood flows continuously in a circuit through the whole
       body, the force propelling it in this unwearied round being the
       rhythmical contractions of the muscular walls of the heart;

 (2) That a portion only of the blood is expended in nutrition each time
       that it circulates;

 (3) That the blood conveyed in the systemic arteries communicates heat
       as well as nourishment throughout the body, instead of exerting a
       cooling influence, as was vulgarly supposed; and

 (4) That the pulse is not produced by the arteries enlarging and so
       filling, but by the arteries being filled with blood and so
       enlarging.

We can now consider the method by which Harvey arrived at these results.
The work, "De Motu Cordis et Sanguinis," after giving an account of the
views of preceding physiologists, ancient and modern, commences with a
description of the heart as seen in a living animal when the chest has
been laid open and the pericardium removed. Three circumstances are
noted--

 (_a_) The heart becomes erect, strikes the chest, and gives a beat;

 (_b_) It is constricted in every direction;

 (_c_) Grasped by the hand, it is felt to become harder during the
         contraction.

From these circumstances it is inferred--

 (1) That the action of the heart is essentially of the same nature as
       that of voluntary muscles, which become hard and condensed when
       they act;

 (2) That, as the effect of this, the capacity of the cavities is
       diminished, and the blood is expelled;

 (3) That the intrinsic motion of the heart is the systole, and not the
       diastole, as previously imagined.

The motions of the arteries are next shown to be dependent upon the
action of the heart, because the arteries are distended by the wave of
blood that is thrown into them, being filled like sacs or bladders, and
not expanding like bellows. These conclusions are confirmed by the
jerking way in which blood flows from a cut artery.

In the heart itself two distinct motions are observed--first of the
auricles, and then of the ventricles. These alternate contractions and
dilatations can have but one result, namely, to force the blood from the
auricle to the ventricle, and from the ventricle, on the right side, by
the pulmonary artery to the lungs, and on the left side by the aorta to
the system.

These considerations suggest to the mind of Harvey the idea of the
circulation. "I began to think," he says, "whether there might not be a
motion, as it were, in a circle." This is next established by proving
the three following propositions:--

 (1) The blood is incessantly transmitted by the action of the heart
       from the vena cava to the arteries in such quantity that it
       cannot be supplied from the ingesta, and in such wise that the
       whole mass must very quickly pass through the organ;

 (2) The blood, under the influence of the arterial pulse, enters, and
       is impelled in a continuous, equable, and incessant stream
       through every part and member of the body, in much larger
       quantity than were sufficient for nutrition, or than the whole
       mass of fluids could supply;

 (3) The veins in like manner return this blood incessantly to the heart
       from all parts and members of the body.

As to the first proposition Harvey says, "Did the heart eject but two
drachms of blood on each contraction, and the beats in half an hour were
a thousand, the quantity expelled in that time would amount to twenty
pounds and ten ounces; and were the quantity an ounce, it would be as
much as eighty pounds and four ounces. Such quantities, it is certain,
could not be supplied by any possible amount of meat and drink consumed
within the time specified. It is the same blood, consequently, that is
now flowing out by the arteries, now returning by the veins; and it is
simply matter of necessity that the blood should perform a circuit, or
return to the place from whence it went forth."

Demonstration of the second proposition--that the blood enters a limb by
the arteries and returns from it by the veins--is afforded by the
effects of a ligature. For if the upper part of the arm be _tightly_
bound, the arteries below will not pulsate, while those above will throb
violently. The hand under such circumstances will retain its natural
colour and appearance, although, if the bandage be kept on for a minute
or two, it will begin to look livid and to fall in temperature. But if
the bandage be now slackened a little, the hand and the arm will
immediately become suffused, and the superficial veins show themselves
tumid and knotted, the pulse at the wrist in the same instant beginning
to beat as it did before the application of the bandage. The tight
bandage not only compresses the veins, but the arteries also, so that
blood cannot flow through either. The slacker ligature obstructs the
veins only, for the arteries lie deeper and have firmer coats. "Seeing,
then," says Harvey, "that the moderately tight ligature renders the
veins turgid, and the whole hand full of blood, I ask, Whence is this?
Does the blood accumulate below the ligature coming through the veins,
or through the arteries, or passing by certain secret pores? Through the
veins it cannot come; still less can it come by any system of invisible
pores; it must needs, then, arrive by the arteries."

The third position to be proved is that the veins return the blood to
the heart from all parts of the body. That such is the case might be
inferred from the presence and disposition of the valves in the veins;
for the office of the valves is by no means explained by the theory that
they are to hinder the blood from flowing into inferior parts by
gravitation, since the valves do not always look upwards, but always
towards the trunks of the veins, invariably towards the seat of the
heart. The action of the valves is then demonstrated experimentally on
the arm bound as for blood-letting. The point of a finger being kept on
a vein, the blood from the space above may be streaked upwards till it
passes the valve, when that portion of the vein between the valve and
the point of pressure will not only be emptied of its contents, but will
remain empty as long as the pressure is continued. If the pressure be
now removed, the empty part of the vein will fill instantly and look as
turgid as before.

Other confirmatory evidence is then added, e.g. the absorption of animal
poisons and of medicines applied externally, the muscular structure of
the heart and the necessary working of its valves.

William Harvey, the illustrious physiologist, anatomist, and physician,
to whom this discovery is due, was the eldest son of a Kentish yeoman,
and was born in April, 1578. At the age of ten he entered the Canterbury
Grammar School, where he appears to have remained for some years. At
sixteen he passed to Caius-Gonvil College, Cambridge, and three years
afterwards took his B.A. degree and quitted the university. Like most
students of medicine of that day, he found it necessary to seek the
principal part of his professional education abroad. He travelled to
Italy, selected Padua as his place of study, and there continued to
reside for four years, having as one of his teachers the famous
Fabricius of Aquapendente. On his return to England, in 1602, he took
his doctor's degree at Cambridge, and entered on the practice of his
profession.

In 1604 he joined the College of Physicians, and three years later was
elected a Fellow of that learned body. Two years afterwards he applied
for the post of physician to St. Bartholomew's Hospital; and his
application being supported by letters of recommendation to the
governor, from the king and from the president of the College of
Physicians, he was duly elected to the office in the same year, as soon
as a vacancy occurred.

In 1615, when thirty-seven years of age, Harvey was chosen to deliver
the lectures on surgery and anatomy to the College of Physicians, and it
is possible that at this time he gave an exposition of his views on the
circulation. He continued to lecture on the same subject for many years
afterwards, although he did not publish his views until 1628, when they
appeared in the work "De Motu Cordis."

Some few years after his appointment as lecturer to the college, he was
chosen one of the physicians extraordinary to King James I., and about
five or six years after the accession of Charles I. he became physician
in ordinary to that unfortunate monarch. The physiologist's
investigations seem to have interested King Charles, for he had several
exhibitions made of the _punctum saliens_ in the embryo chick, and also
witnessed dissections from time to time.

When, in 1630, the young Duke of Lennox made a journey on the Continent,
Harvey was chosen to travel with him, and probably remained abroad
about two years. During this time Harvey most likely visited Venice. Of
this tour the doctor speaks in the following terms in a letter written
at the time: "I can only complayne that by the waye we could scarce see
a dogg, crow, kite, raven, or any bird or any thing to anatomise; only
sum few miserable poeple the reliques of the war and the plauge, where
famine had made anatomies before I came."

Six years after this, in April, 1636, he accompanied the Earl of Arundel
in his embassy to the emperor. Having to visit the principal cities of
Germany, he was thus afforded an opportunity of meeting the leading
biologists of the time, and at Nuremberg he probably met Caspar
Hoffmann, and made that public demonstration of the circulation of the
blood which he had promised in his letter dated from that city, and
which convinced every one present except Hoffmann himself. Hollar, the
artist, informs us that Harvey's enthusiasm in his search for specimens
often led him into danger, and caused grave anxiety to the Earl of
Arundel. "For he would still be making of excursions into the woods,
making observations of strange trees, plants, earths, etc., and
sometimes like to be lost; so that my lord ambassador would be really
angry with him, for there was not only danger of wild beasts, but of
thieves."

Soon after his return to England, as court physician, his movements
became seriously restricted by the fortunes of the king. Aubrey says,
"When King Charles I., by reason of the tumults, left London, Harvey
attended him, and was at the fight of Edgehill with him; and during the
fight the Prince and the Duke of York were committed to his care. He
told me that he withdrew with them under a hedge, and tooke out of his
pockett a booke and read; but he had not read very long before a bullet
of a great gun grazed on the ground neare him, which made him remove his
station.... I first sawe him at Oxford, 1642, after Edgehill fight, but
was then too young to be acquainted with so great a doctor. I remember
he came severall times to our Coll. (Trin.) to George Bathurst, B.D.,
who had a hen to hatch egges in his chamber, which they dayly opened to
see the progress and way of generation."

In 1645, Charles, after the execution of Archbishop Laud, took upon
himself the functions of visitor of Merton College, and having removed
Sir Nathaniel Brent from the office of warden for having joined "the
Rebells now in armes against" him, he directed the Fellows to take the
necessary steps for the election of a successor. This course consisted
in giving in three names to the visitor, in order that one of the three
(the one named first, probably) should be appointed. Harvey was so named
by five out of the seven Fellows voting, and was accordingly duly
elected. A couple of days after his admission he summoned the Fellows
into the hall and made a speech to them, in which he pointed out that
it was likely enough that some of his predecessors had sought the office
in order to enrich themselves, but that his intentions were quite of
another kind, wishing as he did to increase the wealth and prosperity of
the college; and he finished by exhorting them to cherish mutual concord
and amity. After the surrender of Oxford, July, 1646, Harvey retired
from the court. He was in his sixty-ninth year, and doubtless found the
hardships and inconveniences which the miserable war entailed far from
conducive to health. The rest and seclusion to be had at the residence
of one or other of his brothers offered him the much-needed opportunity
of renewing his inquiries into the subject of generation, and it is of
this time that Dr. Ent speaks in the preface to the published work on
that subject which appeared in 1651. "Harassed with anxious and in the
end not much availing cares, about Christmas last, I sought to rid my
spirit of the cloud that oppressed it, by a visit to that great man, the
chief honour and ornament of our college, Dr. William Harvey, then
dwelling not far from the city. I found him, Democritus-like, busy with
the study of natural things, his countenance cheerful, his mind serene,
embracing all within its sphere. I forthwith saluted him, and asked if
all were well with him. 'How can it,' said he, 'whilst the Commonwealth
is full of distractions, and I myself am still in the open sea? And
truly,' he continued, 'did I not find solace in my studies, and a balm
for my spirit in the memory of my observations of former years, I should
feel little desire for longer life. But so it has been, that this life
of obscurity, this vacation from public business, which causes tedium
and disgust to so many, has proved a sovereign remedy to me.'"

Harvey died in June, 1657. Aubrey, his contemporary, says, "On the
morning of his death, about ten o'clock, he went to speake, and found he
had the dead palsey in his tongue; then he sawe what was to become of
him, he knew there was then no hopes of his recovery, so presently sends
for his young nephews to come up to him, to whom he gives one his watch,
to another another remembrance, etc.; made sign to Sambroke his
Apothecary to lett him blood in the tongue, which did little or no good,
and so he ended his dayes.... The palsey did give him an easie
passeport.... He lies buried in a vault at Hempsted in Essex, which his
brother Eliab Harvey built; he is lapt in lead, and on his brest, in
great letters, 'Dr. William Harvey.' I was at his Funerall, and helpt to
carry him into the vault."

The publication of Harvey's views on the movement of the blood excited
great surprise and opposition. The theory of a complete circulation was
at any rate novel, but novelty was far from being a recommendation in
those days. According to Aubrey, the author was thought to be
crackbrained, and lost much of his practice in consequence. He himself
complains that contumelious epithets were levelled at the doctrine and
its author. It was not until after many years had elapsed, and the facts
had become familiar, that men were struck with the simplicity of the
theory, and tried to prove that the idea was not new after all, and that
it was to be found in Hippocrates, or in Galen, or in Servetus, or in
Cæsalpinus--anywhere, in fact, except where alone it existed, namely, in
the work, "De Motu Cordis et Sanguinis." No one seems to have denied,
while Harvey lived, that he was the discoverer of the circulation of the
blood; indeed, Hobbes of Malmesbury, his contemporary, said of him, "He
is the only man, perhaps, that ever lived to see his own doctrine
established in his lifetime."

In one important respect Harvey's account of the circulation was
incomplete. He knew nothing of the vessels which we now speak of as
capillaries. Writing to Paul Marquard Slegel, of Hamburg, in 1651, he
says, "When I perceived that the blood is transferred from the veins
into the arteries through the medium of the heart, by a grand mechanism
and exquisite apparatus of valves, I judged that in like manner,
wherever transudation does not take place through the pores of the
flesh, the blood is returned from the arteries to the veins, not
without some other admirable artifice" (_non sine artificio quodam
admirabili_). It was this _artificium admirabile_ of which Harvey was
unable to give a description. On account of the minuteness of their
structure, the capillaries were beyond his sight, aided as it was by a
magnifying glass merely. He indeed demonstrated physiologically the
existence of some such passages; but it remained for a later observer,
with improved appliances, to verify the fact. This was done by Malpighi
in 1661, who saw in the lung of a frog, which was so mounted in a frame
as to be viewed by transmitted light, the network of capillaries which
connect the last ramifications of the arteries with the radicles of the
veins.

Harvey rightly denied that the arteries possessed any pulsific power of
their own, and maintained that their pulse is owing solely to the sudden
distension of their walls by the blood thrown into them at each
contraction of the ventricles. But the remission which succeeds the
pulse was regarded by him as caused simply by collapse of the walls of
the arteries due to elastic reaction. Knowing nothing of the muscular
coat of the arteries, he was unaware of the fact that the elastic
reaction of the arteries, after their distension, is aided by the tonic
contractility of their walls; the two forces, physical and vital, acting
in concert with each other--the former converting the intermittent flow
from the heart into an even stream in the capillaries and veins; the
latter, through the vaso-motor system, regulating the flow of blood to
particular parts in order to meet changing requirements.

It is somewhat surprising to find that such an accurate observer as
Harvey should have failed to recognize the significance and importance
of the system of lacteal vessels. But such was the case. Eustachius, in
the sixteenth century, had discovered the thoracic duct in the horse,
although he seems to have thought that it was peculiar to that animal.
Aselli, while dissecting the body of a dog in 1622, accidentally
discovered the lacteals, and thought at first that they were nerves; but
upon puncturing one of them, and seeing the milky fluid which escaped,
found them to be vessels. He, however, failed to trace them to the
thoracic duct, and believed them to terminate in the liver. Pecquet of
Dieppe followed them from the intestines to the mesenteric glands, and
from these into a common sac or reservoir, which he designated
_receptaculum chyli_, and thence to their entry by a single slender
conduit into the venous system at the junction of the jugular and
subclavian veins. The existence of the lacteals had not entirely escaped
Harvey, however. He had himself noticed them in the course of his
dissections before Aselli's book was published, but "for various
reasons" could not bring himself to believe that they contained chyle.
The smallness of the thoracic duct seemed to him a difficulty, and as
it was a demonstrated fact that the gastric veins were largely
absorptive, the lacteals appeared to him superfluous. He is not
"obstinately wedded to his own opinion," and does not doubt "but that
many things, now hidden in the well of Democritus, will by-and-by be
drawn up into day by the ceaseless industry of a coming age."

Late in the author's life, as we have seen, the work on the "Generation
of Animals" appeared; but neither physiological nor microscopical
science was sufficiently advanced to admit of the production of an
enduring work on a subject necessarily so abstruse as that of
generation. It was impossible, however, for so shrewd and able an
investigator as Harvey to work at a subject even as difficult as this
without leaving the impress of his original genius. He first announced
the general truth, "Omne animal ex ovo," and clearly proved that the
essential part of the egg, that in which the reproductive processes
begin, was not the _chalazæ_, but the _cicatricula_. This Fabricius had
looked upon as a blemish, a scar left by a broken peduncle. Harvey
described this little cicatricula as expanding under the influence of
incubation into a wider structure, which he called the eye of the egg,
and at the same time separating into a clear and transparent part, in
which later on, according to him, there appeared, as the first rudiment
of the embryo, the heart, or _punctum saliens_, together with the
blood-vessels. He was clearly of opinion that the embryo arose by
successive formation of parts out of the homogeneous and nearly liquid
mass. This was the doctrine of epigenesis, which, notwithstanding its
temporary overthrow by the erroneous theory of evolution,[20] is, with
modifications, the doctrine now held.

Of Harvey's scholarship and culture we are not left in ignorance. Bishop
Pearson, writing about seven years after the doctor's death, and
Aubrey[21] have told us of his appreciation of the works of Aristotle,
and in his own writings he refers more frequently to the Stagirite than
to any other individual. Sir William Temple[22] has also put it on
record that the famous Dr. Harvey was a great admirer of Virgil, whose
works were frequently in his hands. His store of individual knowledge
must have been great; and he seems never to have flagged in his anxiety
to learn more. He made himself master of Oughtred's "Clavis Mathematica"
in his old age, according to Aubrey, who found him "perusing it and
working problems not long before he dyed."

Nor should it be forgotten that this illustrious physiologist and
scholar was also the first English comparative anatomist. Of his
knowledge of the lower animals he makes frequent use, and he says (in
his work on the heart), "Had anatomists only been as conversant with the
dissection of the lower animals as they are with that of the human body,
many matters that have hitherto kept them in a perplexity of doubt,
would, in my opinion, have met them freed from every kind of
difficulty." Aubrey says that Harvey often told him "that of all the
losses he sustained, no grief was so crucifying to him as the loss of
his papers (containing notes of his dissections of the frog, toad, and
other animals), which, together with his goods in his lodgings at
Whitehall, were plundered at the beginning of the rebellion."


FOOTNOTES:

[20] According to the theory of evolution, the egg contained from the
first an excessively minute, but complete animal, and the changes which
took place during incubation consisted not in a formation of parts, but
in a growth, _i.e._ in an expansion of the already existing embryo (see
p. 40).

[21] See p. lxxxii. of "Life," by Dr. Willis.

[22] "Miscellanies:" Part II. on Poetry, p. 314.



INDEX.


 Albertus Magnus, 65

 Alexander the Great, 23, 24

 Andronicus of Rhodes, 27

 "Animals, History of," by Aristotle, 27

 "Animals, On the Parts of," by Aristotle, 31

 Antipater, Governor of Macedonia, 25

 Apellicon, 27

 "Aphorisms" of Hippocrates, 12

 Aristotle, birth, 21;
   youth, 22;
   zoological researches, 24;
   charge against, 25;
   death, 26;
   history of the manuscripts of his works, 26;
   account of his biological writings, 27-44;
   his philosophy of nature teleological, 39

 Arundel, Earl of, 94

 Asclepiads, physical training among the, 4

 Asclepions, description of the, 4

 Aselli, 100

 Aubrey, 95, 97, 98, 102


 Bathurst, George, 95

 Blood, description of, by Aristotle, 31

 Blood, opinions before the time of Harvey as to the movements of the,
          85, 86

 Bogarucci, 76

 Brain, description of the, by Aristotle, 33

 Browne, Sir Thomas, 65


 Cæsalpinus, 98

 Calcar, Jean, 71

 Callisthenes, 24

 Capillaries, discovery of the, 99

 "Corporis Humani Fabrica," 72

 Cuvier's exaggerated praise of Aristotle, 41


 "Dead image of God," the, 65

 "De Anatome," 66

 "De Motu Cordis et Sanguinis," 88-92

 "De usu Radicis Chinæ," 73

 Disease, causes of, 7

 "Disease, The Sacred," 6

 Diseases, natural history of, 9

 Dissection of the human body, 10, 52

 "Divine old man," the, 3

 Don Carlos, cure of, 75

 _Ductus venosus_, observed by Vesalius, 79


 Ent, Dr., 96

 "Epigenesis" and "evolution" compared, 40, 102

 Erasistratus, 47, 58, 85

 Etienne's observation confirmed by Vesalius, 79

 Eustachius, discovery of the thoracic duct of the horse by, 100


 Fabricius of Aquapendente, 85, 92

 Fallopius, anatomical observations of, 77

 "Father of medicine," the, 3

 _Foramen ovale_, valve guarding the, 79

 Franciscus Puteus, reply to, by Gabriel Cuneus, 77


 Galen, birth, 48;
   influence, 49, 60, 65;
   education, 49;
   at Smyrna, 49;
   at Alexandria, 49;
   at Pergamus, 50;
   at Rome, 50;
   return to Greece, 50;
   summoned to meet the Emperors at Aquileia, 50;
   death, 51;
   writings, 51;
   views as to the modes of existence, 52;
   and osteology, 53;
   and the nervous system, 53;
   and the lacteals, 54;
   the heart, 55;
   the arteries, 56;
   and respiration, 57-59;
   made a near approach to the Harveian theory of the circulation, 57

 Generation of animals, the, 38, 101

 Geynes, Dr., 60


 Harvey, date and place of birth, 92;
   at Canterbury School, 92;
   at Cambridge, 92;
   at Padua, 92;
   elected Fellow of the College of Physicians, 93;
   appointed physician to St. Bartholomew's Hospital, 93;
   physician to Charles I., 93;
   foreign travels, 94;
   present at the battle of Edgehill, 95;
   elected Warden of Merton College, 95;
   death, 97;
   discovery of the circulation incomplete in one respect, 98, 99;
   work on the generation of animals, 101;
   a scholar, 102;
   and comparative anatomist, 103

 Heart, description of the, by Aristotle, 35

 Hellebore, administered by Hippocrates, 9

 Hermias, despot of Atarneus, 22;
   murder of, 23

 Herophilus, 47, 58, 85

 Hippocrates, date of birth, 3;
   Greek contemporaries, 3;
   birthplace, 3;
   his freedom from superstition, 5, 16;
   compared with Socrates, 7;
   medical doctrines of, 8;
   works, 10;
   knowledge of osteology, 10;
   traditions concerning, 14;
   oath of, 16

 Hobbes of Malmesbury, 98

 Hoffmann, Caspar, 94

 Humours, the four, 8

 Huxley, Professor, on errors attributed to Aristotle, 37, 42


 Lacteals, the, 54, 100

 Lennox, Duke of, 93

 Lungs, Aristotle's description of the, 37


 Malpighi, discovery of the capillaries by, 99

 Marcus Aurelius, 50

 Marine animals, description of, by Aristotle, 29

 _Mediastinum_, correct description of the, by Vesalius, 79

 Milk in male animals, occasional appearance of, 29

 Mundinus, 66


 Neleus, 26

 Nicon, father of Galen, 49


 _Omentum_, the, and its connections, 80

 Owen, Professor, on Aristotle's knowledge of the cephalopoda, 29


 "Parva naturalia," 27

 Pausanias, 15

 Pecquet of Dieppe, 100

 Peripatetics, the, 24

 Philip, father of Alexander, 22, 23

 "Physiological division of labour," 43

 Plato, 22

 Pliny, 47, 48

 _Pneuma_, 38

 _Punctum saliens_, 35, 93, 101

 _Pylorus_, the, described by Vesalius, 80

 Pythias, 23


 _Receptaculum chyli_, 100

 Roelants, Joachim, 78


 _Scamnum Hippocratis_, 12

 Servetus, 86

 Septimius Severus, 51

 Slegel of Hamburg, 98

 Socrates compared with Hippocrates, 7

 Sprengel's opinion of Galen, 60

 Sylla, 27

 Sylvius, 67, 72, 73, 74


 Teupulus, Paulus, 77

 Theophrastus, 26

 _Theriac_, the, 50

 Thoracic duct, discovery of, 100

 Tyrannion, 27


 Vesalius, birth, 66;
   scholarship, 66;
   studied under Sylvius, 67;
   and Winter of Andernach, 67;
   adventure at Louvain, 67, 68;
   appointed professor at Padua, at Bologna, and at Pisa, 69;
   zeal for correctness in anatomy, 70;
   skill in diagnosis, 70;
   distrusts infallibility of Galen's teaching, 71;
   writes "Fabric of the Human Body," 72;
   is summoned to Ratisbon, 73;
   destroys his manuscripts, 74;
   his success as a practitioner, 75;
   charged with impiety, 75;
   is sent on pilgrimage, 75;
   shipwreck and death at Zante, 76;
   works, 76-80

 _Vis medicatrix naturæ_, 9


 Winter of Andernach, 67





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