|
"It will not be beside the question to show also from
certain
familiar reasonings, that the circulation is both convenient
and
necessary. In the first place, since death is corruption
from
deficiency of heat[117] and since all living things are
warm,
all dying things cold, the heat requires a seat and origin,
a
home and hearth, as it were, in which the tinder of nature,
the first beginning of the innate fire, may be contained and
preserved;
a place from which, as from their origin, heat and
life may flow out
into all the parts, whence nutriment may come
and upon which concoction
and nutrition and all quickening may
depend. That this place is the
heart, that this is the origin of
life as aforesaid, I should hope that
none would doubt.
"Hence the blood has need of motion, of motion
such that it may
return to the heart; for, if sent to the outer parts of
the
body, far from its source,[118] and left unmoved, it would
become coagulated. Heat and spirits are seen to be generated
and
preserved in all by motion, to vanish if quiet supervene.
Therefore, the
blood, thickened or stiffened by the cold of the
extremities and of the
ambient [air] and destitute of spirits,
as in the dead, must needs
return to its source and origin in
order to keep itself whole, to seek
thence and repair again its
heat and spirits."...[119]
"Moreover," Harvey says, a page farther on, "since all animals
live by
nutriment concocted in their interior, it is necessary
that the
concoction and distribution thereof be perfect; and,
further, that a
place and receptacle exist where the nutriment
may be perfected and
whence it may be led off to the several
members. Now this place is the
heart, for it alone of all the
parts contains blood for the public use
in its cavities, the
auricles and ventricles, as in cisterns and
storehouse; not
merely blood for its private use in the coronary vein
and
artery."[120]
In the next chapter we obtain glimpses of the
pathological relations
of this physiology. Harvey brings forward tertian
fever as a case in
point, explaining that the febrile paroxysm is produced
when
"the preternatural heat which has been kindled in the heart
is
diffused throughout the entire body by way of the arteries,
together with the morbific matter which thus is evaporated and
dissolved
by nature."[121]
As a student of the Greek science reads the foregoing
passages,
he clearly sees that the new wine of the circulating blood
is
poured into the old bottles of the Aristotelian physiology; and
Harvey
tells us so himself, in the last chapter of his most famous
treatise. He
says:--
"No less should we agree with Aristotle as to the
sovereignty of
the heart, in dealing with the following and similar
questions:
Does it receive motion and sensation from the brain,
blood
from the liver; or is it the origin of the veins and of
the
blood? For they who try to refute him leave out, or do not
grasp, the main argument, which is that the heart is the first
part to
exist and has in it blood, life, sensation, motion,
before the brain or
the liver has been made or is clearly to
be distinguished, or at least
before either can perform any
function. So the heart with its own proper
organs constructed
for motion--as it were, an internal animal--is the
earlier
formed; and, this being the first made part, it is the will
of
nature that thereafter the entire animal be made, nourished,
preserved, perfected by the heart to be its achievement and
abode. The
heart is governor everywhere, like the chief in
a commonwealth with whom
is lodged the first and highest
authority. In an animal all power is
derived from and depends
upon the heart as its origin and
foundation."[122]
The main argument, which is that the heart is the first
part to
exist, is simply the argument from the development of the
embryo
in the hen's egg. The study of this development day by day had
been
recommended by one of the Hippocratic writers,[123] and
Aristotle had laid
stress upon the changes in the embryo during
incubation.[124] Harvey, in his
turn, had studied them carefully.
The ancients could have made their
observations only with the naked
eye, but Harvey had the aid of a simple
lens, though of nothing
approaching in power to a microscope.[125] In the
treatise of 1628
he speaks as follows of what he thus observed:--
"If you turn to the formation of the chick in the egg, the first
thing
to exist therein, as I have said, is a mere vesicle, or
auricle, or
pulsating drop of blood. Afterward, when growth has
gone on, the heart
is completed.... In a hen's egg after four
or five days of incubation I
have shown the visible presence of
the rudiment of the chick in the form
of a little cloud; in an
egg, that is, which had been immersed in clear
tepid water after
removal of the shell. In the middle of the aforesaid
little
cloud there was a palpitating bloody point, so fine that
in
contracting it disappeared and became invisible, but
reappeared
on its relaxation, looking like the point of a needle, and
of
a ruddy color; so that being now visible and now invisible,
as
though now existent and now non-existent, it evinced
palpitation
and the beginning of life."[126]
In the same treatise
Harvey promises to publish more observations
"on the formation of
the fœtus, where numerous problems of
the following order can find a
place: Why should this point be
made or perfected earlier, that later?
As regards the dominance
of the members: Which part is the cause of the
other? There are
very many problems connected with the heart, such as:
Why should
it be the first thing (as Aristotle says in his third book
on
the parts of animals)[127] to acquire consistency, and be
seen
possessed of life, motion, and sensation, before anything
has
been perfected in the rest of the body? And in like manner
regarding the blood: Why is it before all, and how possessed
of the
beginnings[128] of life and of the animal, and of the
craving to move
and be impelled hither and thither, to which end
the heart would seem to
have been made?"[129]
In Harvey's celebrated treatise, despite various
frank questionings
by the way, such as that just quoted about the blood, he
so
frankly follows in the footsteps of "the master of them that know"
that
Aristotle need not be cited at length to prove the fact. To
Aristotle are
largely due Harvey's references to the heart as
the central source of
indispensable vital heat; his references
to aliment perfected in the heart;
his blending of psychological
doctrines with the doctrine of the movement of
the blood. Therefore,
a brief account of how this became possible will be
germane.
When an ancient observer looked with the naked eye at the very
early
embryo of the fowl, he distinguished at first only a
blood-red
point, which pulsated, or "leapt." This Aristotle judged to be
the
heart, containing blood before any blood-vessel had shown itself
and
before blood was visible in any other part. Very soon, however,
two vessels
containing blood were seen, according to him, to extend
from the rudimentary
heart toward the periphery. From these and
other considerations Aristotle
inferred that both the blood and all
its containing vessels owe their first
origin to the heart; and that
throughout life the liquid made elsewhere from
the food enters the
heart, there to be perfected into blood by the action of
the vital
innate heat, of which, as we have seen, he held the fiery
central
hearth to be within the heart. Naturally, therefore, he believed
the
blood not to be hot of itself, but to acquire its vivifying heat
at
the heart, the pulsation of which he held to be caused directly by
the
seething of the blood within. When thus perfected and charged
with heat the
blood, according to him, is distributed from the heart
through the vena cava
as well as the aorta. These great vessels and
their subdivisions Aristotle
distinguished anatomically; but he
made no serious physiological distinction
between what we call the
veins and the arteries, and, himself, applied the
word "artery" to
the windpipe only. As to the cavities and contents of the
heart,
even as to the number of its cavities, he had obscure, complex,
and
erroneous ideas, and of the valves he knew nothing. He recognized
no
essential differences between the matters distributed by way of
the vena cava
and by way of the aorta, all being, alike, one thing,
blood; though the blood
was hotter or cooler, thinner or thicker,
purer or cruder, in different
regions or parts of the body, in
different sets of vessels, in different
cavities of the heart, or at
different times in the same place.
We
have seen already that, in the genuine works of Aristotle, there
is no sign
that what we call the tissues of the adult require or
receive a derivative of
the air, whether crudely mingled with the
blood in the earlier Hippocratic
way, or separate in Erasistratean
fashion, or in the form of such "spirituous
blood" as Galen
afterward accepted. We have seen that the air which
Aristotle
believed to enter the heart for cooling purposes, cannot be
traced
beyond it; that whatever spirits may exist in the body for
him,
would seem to be either of the nature of vapor produced within
the
body itself, or of a nature quite indeterminate.[130]
The living
egg of the hen has had a vast deal to do with the history
of psychology as
well as of physiology. It is partly owing to what
Aristotle believed to go on
in the egg that we speak to-day of
good hearts and bad hearts--even of
sweethearts. Aristotle knew
nothing of the nerves, and, therefore, could
reasonably fail to find
conclusive evidence that the brain and spinal cord
had to do with
what we call nervous functions. So he fell back upon a
doctrine at
least as old as the Iliad,[131] and made a psychological center
of
the heart. This being proved, for Aristotle, largely by its demeanor
in
the early embryo, to be the life-long source of the nutritive
blood; and
being, for him, the central hearth of the heat by means
of which the blood is
perfected and warmed; he held it a matter of
necessity that in the heart
should dwell the so-called "nutritive
soul"; that is, the faculty which uses
as its most immediate
instrument the "innate," "natural," "vital,"
"psychical," heat, to
bring about nutrition, growth, and generation. He
says:--
"It is impossible that the other faculties of the soul
should
exist without the nutritive, or these without the natural
fire;
for in this has nature set that faculty
aglow."[132]
Dealing with these other faculties, he sees that there must
be an
organ where the results of sight, hearing, and the other senses,
are
compared; and deliberately discussing and rejecting the claims
made
for the brain he makes the heart this "common sense-organ of all
the
sense-organs," as he styles it. He says:--
"If in all the
creatures the seat of life is in this part, it is
clear that here also
must the origin of sensation be; for we say
that the body has life
because it is an animal, but we say that
it is animal because it has
sensation."[133]
Less hollow rings the argument in the modern ear, when
the ancient
thinker bases it on conclusions drawn from observation. We
learn
from him that only those parts are sensitive which contain blood,
as
opposed to hair and nails, or even to the blood, if taken by itself.
We
learn, therefore, that as the heart of the embryo is the first
part to
contain blood, it is the first part to be sensitive and
hence is the central
source of sensation. Moreover, Aristotle, like
Plato,[134] knowing nothing of
the nerves, judges the blood-vessels
to be sensory paths; and blood-vessels
connect, not only the
sensitive flesh, but all the more special sense-organs
with the
heart. Such is the outline of the reasons why Aristotle held
the
heart to be the lifelong seat, not only of the "nutritive soul,"
but
of the "sensory soul" as well.
Pain, pleasure, and desire would
naturally dwell beside sensation
in the heart, which Aristotle held to be
obviously the seat of the
emotions, as proved by its palpitation when they
are stirred.
Moreover, it is desire, seated in the heart, which incites
to
action, to motion, movement thus resulting from sensation; and,
in
general, "the movements" of every sense both begin and end at
the heart; the
word here translated "movement"[135] being used, in
the technical diction of
Aristotle, to include not only the "molar
motion" of modern parlance, but
also subtle forms of change of
state. Further, in the early embryo the heart
itself is plainly the
first part which possesses motion; it visibly taking
the lead in
this, moving "as though itself an animal." The pulsating
movements
of the heart are the direct effects of the seething and
vaporization
within it; while, in the respiratory movements, the chest wall
is
pushed out by an expansion due to the vital heat, whose cardiac
hearth
the lungs inclose, and then follows inward a contraction due
to the cooling
air which has been drawn into the expanding lungs.
As the bodily movements,
in general, are "brought about by drawing
and slackening" and originate at
the heart, it is appropriate that
the heart contains tendinous
structures[136] within itself; "for
it needs the service and strength" of
such.[137] It is too, in a
sense, the origin of the discontinuous tendinous
and ligamentous
structures of the body. Aristotle's doctrine of the heart as
the
source of motion seems especially vague. But, hardy thinker though
he
was, he scarcely could be definite on this subject, even in
speculation. He
knew that heat expands and cold contracts; he
recognized the force which, as
he believed, confined or compressed
vapor exerts in living bodies, not only
in health but in disease;
and he knew the strength imparted to bodily effort
by holding the
breath. His genuine writings, however, bring forward no
_modus
operandi_, except in the case of respiration and of the
movements
of the heart itself. We are given no inkling as to how the
tendons
are normally drawn and slackened in obedience to the will, for
the
true function of muscle was unknown to Aristotle (Harvey to
the
contrary notwithstanding),[138] and the blood-vessels were the
only
continuous special paths between center and periphery which
Aristotle could
make out. In his time, as we have seen, the nerves
had not been
distinguished, even anatomically, from the bands and
cords of the ligaments
and tendons.
So, for Aristotle, the nutritive, sensory, and motor
faculties, the
desires and emotions, in short all the souls or parts of the
soul
(to use the ancient phraseology) that are not the most exalted,
dwell
in fire within the heart, suitably and honorably placed at the
central
"acropolis." To the divine mind of man, on the other hand,
he does not assign
a definite special dwelling-place within the body.
Harvey differed often
and widely from Aristotle. Yet even in
his old age he wrote: "The authority
of Aristotle has always
such weight with me that I never think of differing
from him
inconsiderately."[139] Cannot one fancy, may not one
conjecture,
that in the eyes of the discoverer of the circulation his
great
discovery, fundamental, new, and original, as he rightly claimed
it
to be, may at times have seemed to constitute a thorough correcting
and
filling in of a rough sketch dashed off at the Lyceum? Let
us
see.
Aristotle had no conception of anything resembling a
circulation of
the blood, nor any definite mechanical ideas as to its
movement.
While the vena cava as well as the aorta received blood from
his
valveless heart and yielded it to the body at large, blood ebbed
back
to the heart during sleep, and the warm nutrient liquid which
the vena cava
and the aorta yielded to the tissues had previously
entered the heart
continuously but in an imperfect state through
both of these great vessels,
to go forth again through both,
perfected into blood and heated, with no
perplexing differences of
color noted between that in the great vein and that
in the aorta.
The relations between the food, the blood, the heart, and the
body
at large, though recognized to be complex, may well have
presented
themselves to Aristotle with something of the vagueness with
which
the relations between the food, the liquids, the
contractile
vacuole, and the living substance of a protozoon, present
themselves
to us. If the heart, retaining its Aristotelian powers, were
found
to receive the blood imperfect or impaired, but to receive it by
the
veins only, and to send it out, but only by the arteries, warmed
and
perfected or restored to perfection at its Aristotelian source;
what
have we but the systemic part of the circulation, as it may
have
pictured itself sometimes to Harvey?[140]
CHAPTER
V
PHYSICIANS _versus_ PHILOSOPHERS--HARVEY FOR THE
PHILOSOPHERS
Thus it is striking to find Harvey, as the champion
against Galen of
a view essentially Aristotelian, entering the field of
controversy
where ancient Greek still met ancient Greek in the modern Europe
of
1628.
The discoveries of the nerves and the valves of the heart
had
made great difficulties for the Aristotelian psychology and
physiology
shortly after Aristotle's time. We have seen that the
semilunar valves were
described, and their use noted, in a treatise
included in the Hippocratic
collection;[141] and all the valves,
both arterial and auriculo-ventricular,
were well recognized by
Erasistratus, whose acquaintance we have made
already, and who
flourished about 300 B.C., Aristotle having died in 322
B.C.
Erasistratus, we remember, was more than four centuries earlier
than
Galen and more than nineteen centuries earlier than Harvey.
That
the heart throughout life is not only the source of the
perfected blood, but
gives out blood to the vena cava for
distribution, had been rendered a hard
saying, especially by the
recognition of the tricuspid valve.[142] Galen,
however, like the
somewhat earlier Greek physician Aretæus, the
Cappadocian,[143]
was not confronted by this difficulty, for they both
adhered to
an ancient doctrine to be found in the Hippocratic treatise
"On
Nourishment," and there sketched with mingled clearness and
vagueness in the
following pithy saying:--
"Root of the veins, the liver; root of the
arteries, the heart.
Out of these wander into all parts blood and
spirits, and
through these heat comes in."[144]
Obviously the
doctrine here foreshadowed was quite irreconcilable
with the views of
Aristotle.
In studying the works of Harvey and of his contemporaries
and
predecessors it must be borne in mind that, from ancient times
past
the time of Harvey to more modern days, the word "heart" was
very
commonly used by physicians and men of science to mean simply
the
ventricular mass, without the auricles, which were reckoned in
with
the great vessels. In slaughterhouses the word is still used in
this
ancient sense. Harvey's practice was fluctuating; for the word
is
used by him sometimes to mean the ventricular mass only, sometimes,
as
in the science of to-day, to mean the ventricular mass and the
auricles taken
together.
According to the more detailed views of Galen and his school
the
blood was perfected and had its central source not in the heart,
but
in the liver, to which the portal vein brought a cruder liquid
derived from
the products of digestion. In the liver the veins
also originated, while the
arteries originated at the heart. The
blood left its source in the liver, by
way of the roots of the
venous system, that is, by the hepatic veins of
modern anatomy.
From these it entered the great venous trunk, the vena cava,
a
vessel which comprised the inferior cava, the right auricle, and
the
superior cava of our present nomenclature. Upon leaving the
liver the blood
at once divided into two sharply diverging streams,
one flowing directly
downward through the vena cava, the belly, and
the lower extremities; the
other stream flowing directly upward
through the vena cava to the chest, the
upper extremities, and the
head. Therefore, that part of the vena cava which
we call the right
auricle simply formed a part of the upward pathway of the
blood, at
a place where some of the blood left this upward pathway and
flowed
through a side opening into the right ventricle. This
ventricle,
therefore, received only a fraction of that portion of the
blood
which ascended from the liver. The rest of the ascending
blood
mounted in the vena cava past the right opening which led into
the
ventricle and, having traversed thus what we call the right
auricle,
entered and traversed what we call the superior vena cava, to
be
distributed to the veins and tissues of the arms and head. Of
the
fraction of the blood that entered the right ventricle a part went
to
the lungs simply for their nutrition, by the "arterial vein"--the
pulmonary
artery of modern parlance--and a part percolated in
a refined condition
through pores of the septum from the right
ventricle to the left, to be
worked up there with the vital spirits
and thus become the basis of the
spirituous blood of the arteries.
From the left ventricle this spirituous
blood went to the body
at large by way of the arteries. There is no evidence
that Galen
believed any blood to pass from the right to the left
ventricle
otherwise than through the pores of the septum. As he says,
however,
that the branches of the "venous artery" (our pulmonary
vein)
"transmit thin and pure and vaporous blood in abundance" to
the
lungs for their nutrition,[145] we may infer that he held this
supply
to be derived from the left ventricle like that of the rest
of the body. This
was possible, according to Galen's system, because
he held to the irrational
opinion that what is now called the mitral
valve closed less perfectly than
the other valves, inasmuch as it
possessed only two segments instead of
three.
This supposed imperfection of the mitral valve played an
important
part in Galen's system, for it was possible thereby for the lung
to
receive, not only some spirituous blood from the left ventricle of
the
heart, but also, and especially, the injurious fumes which Galen
held to
arise from combustion in the left ventricle, to escape into
the venous artery
past the imperfect mitral valve, and to be exhaled
in expiration. When this
valvular door was open, therefore, the left
ventricle drew from the lungs
into itself crude spirits, these to
be returned in some part perhaps to the
lungs as spirituous blood
in company with the deleterious fumes, when the
valvular door was
only ajar. This imperfection of the valve of two segments,
however,
was but a constant and fortunate exaggeration of a condition
shared
to a slight degree by all the valves; for Galen held these, in
the
act of closing, to allow slight regurgitation of spirits, vapor,
or
even of blood; and to do so exceptionally even when closed, if
the
movement of the heart were of unusual force. He commonly,
however,
assumed the tricuspid, pulmonary, and aortic valves to be
competent,
especially if he could gain a polemical point by doing
so.[146]
More than thirteen centuries later Columbus, as we have
learned,
announced that blood from the right ventricle entered the
left
ventricle, not by pores of the septum, but exclusively by pores
of
the lungs, in passing through which latter it became spirituous
blood,
needing but little elaboration in the ventricle before
entering the arteries
for distribution to the body. Columbus denied
and derided the passage of
fumes from the left ventricle to the
lungs, while he accepted the ancient
doctrine of the cooling effect
of respiration. His view of the meaning of the
pulmonary transit is
therefore a striking approximation to the truth--a
closer one than
that of Harvey, who questioned everything except the fumes
given off
in expiration, which fumes, of course, Harvey did not send along
the
Galenic path. As Columbus declared the spirituous blood to be made
up
in the lungs, and these, therefore, to need no supply thereof
from the left
ventricle; and as he also denied the passage of fumes
through the venous
artery; the flow through the latter became
simplified, spirituous blood alone
passing through it, and in the
true direction from the lungs to the heart.
Accordingly the mitral
valve also was cured of its Galenic imperfection; to
the latter
Columbus does not even refer, but he simply describes all the
four
valves as competent.
Columbus, therefore, set forth the true
course, and in no small
degree the true nature and meaning, of the movement
whereby blood
passes from the right auriculo-ventricular ring to the aorta,
and
in so doing he expelled important errors from the Galenic system.
But,
strange to say, by thus purging it he greatly strengthened
it, as was
mentioned earlier in this paper, for he harmonized
the fundamental doctrine
of the Galenic system with the true
mechanism and working of the cardiac
valves, and with a rational
theory of respiration.[147] This fundamental
Galenic doctrine was
the direct distribution of blood to the tissues through
the veins
from the liver as a center; no more than a fraction of the
blood
ever passing the tricuspid valve to reach the lungs or to enter
the
arteries as spirituous blood. Of this doctrine Columbus was not
only
an adherent, but a warm partisan against the Aristotelians;
and, like Galen
more than thirteen centuries before, Columbus
points with emphasis to the
tricuspid valve as evidence of the
falsity of the Aristotelian doctrine that
crude blood enters the
heart to be perfected and returned thence to the vena
cava for
distribution.[148] The Galenic view that the liver is the origin
of
the veins and the source of the blood, by which word, unqualified,
was
meant the venous blood, was known even down to Harvey's day
as the view of
"the physicians," as opposed to that of "the
philosophers," who contended in
ingenious ways for the view of the
great philosopher Aristotle that the heart
is the origin of the
veins and the source of the blood. Harvey in this
contest repeatedly
ranges himself in his writings with the Aristotelians and
against
the Galenists;[149] we shall see him bring the circulation into
play
to give very effective aid to the former against Galen
himself.
Bearing in mind the Galenic meaning of the word "blood,"
and
remembering that, in spite of the weak points in Galen's own armor,
he
possessed in the tricuspid valve a formidable weapon against
the followers of
Aristotle, listen to the following passage from
Harvey's treatise of 1628. He
says:--
"Whether or no the heart imparts anything more to the
blood
than transposition, locomotion, and distribution, whether
it
imparts heat also, or spirits, or perfection, must be looked
into later and gathered from other observations. For the present
be it
enough to have shown sufficiently that during the beat of
the heart the
blood is transfused and withdrawn from the veins
into the arteries
through the ventricles of the heart, and is
distributed to the body at
large.
"This, to be sure, is conceded by all after a fashion, it
being
gathered from the structure of the heart and the
arrangement,
position, and use of the valves. But they seem to waver
blindly
as though in a dark place, and they put together varied,
incoherent, and more or less contradictory doctrines and,
indeed, set
forth much upon conjecture, as has been shown
already.
"There seems to me to have been one single principal cause
of hesitation
and error in this matter, viz.: the connection
between the heart and the
lung in man. The disappearance of
the arterial vein in the lungs having
been noted, and likewise
that of the venous artery, great obscurity
prevailed as to
whence or how the right ventricle distributed the blood
to the
body, or the left ventricle drew blood from the vena cava.
This
is attested by the words of Galen when he inveighs against
Erasistratus regarding the origin and use of the veins and the
coction
of the blood. 'You will answer,' Galen says, 'that the
way of it is
this: that the blood is prepared beforehand in the
liver and is
transferred thence to the heart to receive the rest
of its proper
character in complete perfection. Surely this does
not seem devoid of
reason; for no great and perfect work can
be accomplished suddenly at
one attempt and receive its entire
polish from a single instrument. If
then this be so, show us
another vessel which leads the completely
perfected blood forth
from the heart, and distributes it to the whole
body as the
artery does the spirits.'[150] Behold Galen disapproving
and
putting aside a reasonable opinion because, besides not
seeing
the path of transit,[151] he cannot find a vessel to
distribute
the blood from the heart to the whole body!
"But
had there been anyone on the spot to take the part of
Erasistratus or of
that opinion which is now our own and is
confessed by Galen himself to
be reasonable in other respects;
and had the person aforesaid pointed
his finger at the great
artery [aorta] as the distributer of the blood
from the heart
to the body at large,--I wonder what answer that divine
man
would have made, full of genius and of learning as he was!
Had
he said that the artery distributed spirits and not blood,
he
certainly would sufficiently have refuted Erasistratus, who
believed that only spirits were contained in the arteries; but
in so
doing Galen would have contradicted himself and would
shamefully have
denied what he sharply contends to be true in a
special book[152] which
he wrote against that same Erasistratus.
For he proves by many powerful
arguments, and demonstrates by
experiments, that blood, and not spirits,
is naturally contained
in the arteries.
"But since the
divine man concedes, as he often does in that
same place, 'that all the
arteries of the body arise from the
great artery, and this from the
heart; and that for a certainty
blood is naturally contained and borne
onward in all of them,'
he maintaining 'that the three sigmoid valves
placed at the
orifice of the aorta forbid the return of blood into the
heart,
and that nature would never have set these valves in
apposition
to the most preeminent of the viscera were the valves not to
do
it some most important service;'--since, I say, the father of
physicians concedes all this and in these very words, as he does
in the
book aforesaid, I do not see how he can deny that the
great artery is
the vessel adapted to distribute the blood, now
arrived at complete
perfection, from the heart to the body at
large."[153]
Thus does
the great English discoverer bring the pulmonary transit
and the circulation
of the blood to the rescue of the Aristotelian
heart, despite Galen and the
tricuspid valve! Between Harvey and
the school that refused to the heart more
than a fraction of the
blood, there could be no peace. It is the Galenists
whose system
he attacked and shattered so thoroughly; and those who long
and
bitterly opposed the acceptance of the Harveian circulation were
of
the Galenic school. In a private letter written twenty-three
years
after the publication of his discovery, Harvey excuses the
French
physician Riolanus for having slighted the circulation not
long
before, saying, among other things:--
"It was proper that
the dean of the College of Paris should keep
the medicine of Galen in
repair; and should admit no novelties
into his school without the utmost
winnowing."[154]
CHAPTER VI
THE CIRCULATION AND THE
PRIMACY OF THE BLOOD
We have found the discoverer of the circulation
an admirer and
defender of Aristotle; but we shall leave him far less
Aristotelian
than we found him. Before he died, he had transferred to the
blood
itself that physiological primacy which Aristotle had given to
the
heart; Harvey having come to regard the blood even as the very seat
of
the soul, harking back to a Greek doctrine older than Aristotle
and expressly
discountenanced by him.[155] This final view of Harvey
was not simply an
outcome of his old age, though he develops and
formally declares and insists
upon the doctrine of the primacy
of the blood in the writings which he
published when beyond the
age of seventy, more than twenty years after the
publication of
his treatise of 1628. We have seen that in this his most
famous
work he adheres impressively to the Aristotelian doctrine of
the
primacy of the heart; though even this work contains utterances
of
Harvey which do not well accord with that doctrine. More than
eleven years
earlier, when making notes for his lectures of 1616,
he asked himself in
striking terms, whether the circulation do not
exist in order that the blood
may be heated by the heart.[156]
Yet there are passages in those very same
notes which show that,
beside vaguer conjectures,[157] the doctrine of the
primacy of the
blood was present clearly to Harvey's mind even so early as
in
his thirty-seventh year. In his lecture notes four passages
are
especially significant as to this doctrine. Of these the first is
as
follows:--
"Yf I could shew what I hav seene, y^t weare att an
end between
physicians et philosophers."
After these words in
English Harvey falls into his usual Latin,
which may be translated
thus:--
"For the blood is rather the author of the viscera than they
of
it, because the blood is present before the viscera, nor yet
coming from the mother,[158] for in the egg there is a drop. The
soul[159] is in the blood."[160]
In a second passage of his note-book
Harvey says, speaking of the
heart:--
"It is most exceeding full
of contained blood, as no other
viscus is. Wherefore Aristotle [holds]
against the physicians
that the origin of the blood is not in the liver
but in the
heart, because in the liver there is no blood outside the
veins.
Rather is the blood the origin of both, as I have
seen."[161]
In a third passage Harvey says of the heart that
its
"temperature is exceeding hot, inasmuch as it is exceeding
full
of blood."[162]
In a fourth passage of the lecture notes
which bears upon the
primacy of the blood we may read:--
"1. [The
heart] is the most principal part of all, not because
of itself,[163]
for its flesh is more fibrous and harder and
colder than the liver, but
because of the abundance of blood and
spirits in the
ventricles.
"1. Whence the fount of the entire heat.
* * * * *
"Whence the auricles pulsate,
after removal of the heart,
because of the multitudinous
blood.[164]
"2. Nor is [the heart] the principal part because of its
origin:
for I believe that the ventricles (which in the fœtus
are
both united as in fishes) are made out of a drop of blood
which
is in the egg; and that the heart, together with the rest
[of
the parts] all sprout[165] simultaneously, as [occurs] in an
ear of corn, from an imperceptible size. Is there only a drop
of blood
in the auricles whence bestowing heat upon all parts,
receiving from
none, it is the citadel and domicile of the heat,
the household
shrine[166] of that edifice, fowntayn conduit
hed."[167]
More
than eleven years after the making of his lecture notes Harvey,
at the age of
fifty, published his treatise of 1628; and later,
after keeping silence for
more than twenty years, he published
together the two Exercises addressed to
Riolanus. During these
twenty years and more the blood must have been rising
and the heart
declining, in Harvey's esteem, as ruling powers in the body;
for at
the end of that time more than thirty-two years after the
jotting
down of the statements and varied conjectures of his lecture
notes,
he formally throws over Aristotle's primacy of the heart, in
a
passage near the close of the second Exercise to Riolanus. Of
this
passage the following is a part. Referring to certain
opinions,
mainly Aristotelian, regarding the heart and blood, Harvey
says:--
"To speak openly, I do not believe that those things are so
in
the sense commonly received; and my opinion is inclined in
the
direction aforesaid by much which is visible in the
generation
of the parts, but which is not convenient to set down
here.
Soon, perhaps, I shall make public things even more
wonderful
and destined to cast even greater light upon natural
philosophy.
"For the present I will only say and set forth
without
demonstration--by good leave of the learned and with due
respect
to the ancients--that the heart, as the beginning,
author,
source, and origin of everything in the body and the
first
cause of life, should be held to include the veins and all
the arteries and also the contained blood; just as the brain,
including
all its nerves and sensory organs and spinal marrow,
is the one adequate
organ of sensation, as the phrase is. If by
the word 'heart,' however,
only the body of the heart be meant
with its ventricles and auricles, I
do not believe that it is
the manufacturer of the blood; nor that the
blood possesses
vigor, faculty, reason,[168] motion, or heat, as the
gift of the
heart."[169]
In the second year after that of the
Exercises to Riolanus Harvey's
final publication, his treatise On Generation
with appended essays,
was given to the world, not long before his
seventy-third birthday.
During how many years this work had been in
preparation we do not
know; but it is avowedly based upon the views of
Aristotle, whom
Harvey styles his "_dux_"--his leader--as regards the
subject
of this treatise.[170] In it, to be sure, the ancient master
is
often weighed in the balance and found wanting by Harvey, who
even
questions whether Aristotle had seen for himself what he "narrates
as
to the generation of the chick," or "had accepted it from some
expert."[171]
Nevertheless, it is with the doctrines of Aristotle
that Harvey incessantly
compares the results of observation. Here
the veteran records anew his denial
of the Aristotelian primacy of
the heart, and records as well his final
emphatic assertion of the
primacy of the blood. In regard to these matters it
is interesting
to note the various grades of expression which appear to
mirror in
this single work the various phases of Harvey's thought.
In
the following florid passage doubt of the primacy of the heart
seems hardly
even hinted at. Harvey says:--
"Certain of the parts themselves are
said to be generative, such
as the heart, from which Aristotle declares
that the rest of the
parts derive their origin; as is also clear from
the history
which I have given. The heart, I say--or at least its
first
beginning, to wit, the vesicle and leaping point--constructs
the
rest of the body to be its future abode; enters this when
once
built up, and hides in it, vivifies and governs it; fortifies
it
with ribs and sternum super-imposed as a bulwark; and is a
kind
of household shrine, as it were, the first seat of the soul,
the
first receptacle and perennial soul-endowed[172] hearth of
the
innate heat, the source and origin of all the faculties, and
their sole relief in calamity."[173]
Divergence from Aristotle in the
matter of the heart is plainly
marked, however, in the following passage of
the same treatise,
where Harvey says:--
"We find the blood formed
before anything else in the egg and
in the product of conception;[174]
and almost at the same time
the receptacles of the blood, the veins and
the pulsating
vesicle, become plainly visible. Wherefore, if the leaping
point
together with the veins and blood, which are all
conspicuous
as one single organ at the first beginning of the embryo,
be
accepted as the heart (the parenchyma of which is superadded
to the vesicle later in the formation of the embryo), it is
manifest
that, accepted in this sense, that is, as an organ
composed of
parenchyma, ventricles, auricles, and blood, the
heart in animals is in
very truth, as Aristotle would have it,
the principal and first
generated part of the body; of which
part, however, the first and
foremost part is the blood, both by
nature and in the order of
generation."[175]
In the following third passage of the same treatise no
reconciling
interpretations of the master's words are to be found;
flat
disagreement with Aristotle is declared; and the "Sun of
the
Microcosm"[176] declines nearly to its simple modern status of
a
living pump! Harvey says:--
"Nor can I agree with Aristotle
himself, who maintained that
the heart is the primary generative part
and that it is endowed
with soul; for, truly, I believe the blood alone
to be entitled
to these distinctions, since the blood it is which first
appears
in generation; and that such is the case not only in the egg
but
also in every fœtus and very early animal embryo, shall at
once be made plain.[177]
"At the beginning, I say, there appear the
red leaping point,
the pulsating vesicle, and filaments, derived thence,
which
contain blood in their interior. And, so far as can be
discerned
by accurate inspection, the blood is made before the
leaping
point is formed, and the blood is endowed with vital heat
before
it is set in motion by pulsation; and, further, as
pulsation
is begun in and by the blood, so at last it ends in the
blood
at the final instant of death. Indeed, by numerous
experiments
done upon the egg and otherwise I have made sure that it
is
the blood in which the power of returning to life persists,
so
long as the vital heat has not wholly vanished. And since the
pulsating vesicle and the sanguineous filaments derived from it
are seen
before anything else, it stands to reason in my belief
that the blood is
prior to its receptacles--the contained, that
is, to its
container--since the latter is made for the use of
the former.
Therefore, it is probable that the filaments and
the veins and then the
vesicle and at length the heart, having
organs destined to receive and
retain the blood, are made for
the sole purpose of transmitting and
distributing it, and that
the blood is the principal part of the
body....
"Therefore, relying with certainty upon what I have
observed
in the egg and in the dissection of living animals, I
maintain
against Aristotle that the blood is the primary
generative
part; and that the heart is its organ, destined to send it
on
a circuit. Surely the function of the heart is the propulsion
of the blood, as is admirably clear in all animals that have
blood; and
in the generation of the chick the same duty falls
to the pulsating
vesicle, which in the very early embryos of
animals[178] no less than in
the egg I have often exhibited to
view as something more minute than a
spark, beating and when in
action contracting itself and at the same
time pressing out the
blood contained in it, and in its relaxation
receiving the same
afresh."[179]
Whether in studying the
foregoing passages we read Harvey's earlier
jottings in his private note-book
or the deliberate statements
published in his old age, it is evident that to
his mind the
question of the primacy of the blood versus the primacy of
the
heart depends for answer upon the further question whether in
the
development of the embryo the blood be made before the heart, or
the
heart before the blood. In no other part than one of these two
can the
primacy inhere, for him; and whichever of these two has the
priority must be,
to Harvey's mind, the origin of the other and of
the remaining parts and must
continue to be the "principal part" of
the body throughout life. The matter
of the primacy thus resolves
itself into one of well-devised and accurate
observation; and the
discoverer is once more upon the ground where his
undying laurels
grew. He, therefore, deals no longer "without demonstration,"
as
in the second Exercise to Riolanus, but makes report of
actual
observations and so gives ocular evidence in support of his
views,
remembering, it may be, that he had said to Riolanus:
"Soon,
perhaps, I shall make public things even more wonderful and
destined
to cast even greater light on natural philosophy."[180]
Harvey's
contemporary Milton said to Parliament: "Truth is compar'd
in
Scripture to a streaming fountain; if her waters flow not in
a
perpetuall progression, they sick'n into a muddy pool of conformity
and
tradition."[181] These words seem timely as we note the great
discoverer,
magnifying glass in hand, searching in incubated eggs
for an answer to the
question, now wholly obsolete, whether the
primacy of the heart should not
give way to the primacy of the blood.
"Surely," says Harvey, "this
investigation is one of great
moment, to wit: whether or no the blood be
present before the
pulse; and is the point[182] derived from the veins
or the
veins from the point? So far as I have been able to
observe,
the blood appears to exist before the pulse; and I will
show
cause for this opinion as follows: On a Wednesday evening I
put
three eggs under a hen; and having come back on the Saturday,
a
little before the same hour, I found these eggs cold as though
deserted by the hen. I opened one of them, nevertheless, and
came upon
the beginning of a chick, namely, a red sanguineous
line at the
circumference,[183] but at the centre instead of
the leaping point a
point which was white and bloodless. By
this sign I perceived that the
hen had left off sitting not
long before. So I caught her, shut her up
in a box, and kept
her there the entire night; that is, after I had put
under her
the two remaining eggs together with other fresh ones. What
was
the result? Next day in the very early morning both eggs had
revived; and at the centre the beating point itself was visible,
much
smaller than the white point; out of which, that is, out of
the white
one, it made its appearance in diastole only, like a
spark leaping forth
from a cloud: so that the red point seemed
to me to flash out of the
white point; the leaping point being
generated in the latter, in one way
or another; and the blood
to be already in existence, when the leaping
point is brought
into existence or at least into motion. Indeed, I have
very
often found that even when the leaping point lies still and
devoid of all motion as though quite dead, it recovers motion
and
pulsation again if warmed afresh. From the foregoing I
judge that in the
order of generation the point and the blood
come into existence first;
but that pulsation does not come on
till afterward. Certainly this is
settled, viz.: that of the
future embryo nothing at all appears on this
day[184] except the
sanguineous lines and the leaping point and also
those veins
which grow all from one trunk (as this grows from the
leaping point) and are dispersed throughout the entire colliquative[185] region
in very many ramified filaments.... |
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