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Harvey's Views on the Use of the Circulation of the Blood, by
John G. Curtis
PREFATORY NOTE
The writings of William
Harvey, as published by him, and the letters
published as part of his works,
are all in Latin. The passages from
Harvey's works which appear in English in
the present paper are in
part translations by the late Dr. Willis, with
changes, sometimes
considerable, by the present writer. In large part,
however, the
translations from Harvey are not even based upon Dr. Willis's
work,
but have been made by the present writer directly from the
original
Latin. Naturally he assumes responsibility for whatever he
prints
in English to represent Harvey's words; and to attempt, in print,
a
more minute discrimination between his own work as a translator
and that of
Dr. Willis would be tedious and unprofitable. Whoever
may wish to make such
discrimination may readily do so, however,
as, in the present paper, a
reference is made by page and line in
the case of each translated passage,
not only to the Latin text of
Harvey's _Opera Omnia_, published by the Royal
College of Physicians
of London in 1766, but also to Willis's English
translation thereof,
published by the Sydenham Society in 1847, and entitled
"The Works
of William Harvey, M.D." Such references to the Sydenham
Society's
edition are indispensable for another purpose, viz.: in order
that
to each translated passage from Harvey in the present paper a
context
in English may readily be given by the reader.
It has seemed best that
the various references to Harvey's Latin
text should be made to that of the
easily accessible _Opera Omnia_
rather than to that of the rarer first
editions of the several
treatises. In the case of the passages quoted from
the treatise _De
Motu Cordis et Sanguinis in Animalibus_ and from the
treatise _De
Generatione Animalium_, the Latin of the _Opera Omnia_ has
been
collated by the present writer with that of the first editions.
The
first editions of the Exercises to Riolanus and of the various
letters have
not been accessible to him.
Much use has here been made of Harvey's
private lecture notes, first
published in 1886 by the Royal College of
Physicians of London.
All the passages (except those from the Scriptures)
quoted in the
present paper from writers other than Harvey have been
translated
into English by the present writer directly from the original
Greek
text or the original Latin text, as the case may be.
JOHN G.
CURTIS.
EDITORIAL NOTE
Professor Curtis, to whom I
am indebted for much kindly help
extended during a warm friendship of nearly
thirty years, died
September 20, 1913. One of his final requests was that his
younger
colleague arrange for the publication of the present paper,
upon
which its writer had been engaged for a period of several years
and
which happily was practically completed. This request, coming
to me after the
death of my friend, could be considered only as a
command. It has, therefore,
fallen to me to make a careful study of
his text, to fill in with my own
words occasional slight gaps, to
make occasional verbal changes, to certify
to the correctness of
his numerous references, and to make the manuscript,
written and in
places rewritten many times with his own hand, ready for the
press.
This I have done with affection for his memory and with
appreciation
of his scholarly attainments. Dr. Curtis's work represents a
more
profound study of Harvey's ideas and comparison of them with those
of
the most important of Harvey's predecessors than has heretofore
appeared. It
is the work of one who from the background of the
physiological science of
to-day delighted in mastering the ideas of
the fathers of modern physiology.
If his work is to be summarized
in a single sentence, it may be said that he
has shown Harvey to
be a disciple more of Aristotle than of Galen. Although
Harvey
had the courage and the originality to break away from him
whose
ideas had prevailed for fourteen centuries, and to find the truth
in
regard to the movement of the blood, he found much to approve in
the master
who had lived five hundred years before Galen. Harvey's
true position in the
world of physiological thought has not before
been made known. Herein lies
Professor Curtis's contribution to the
history of his
science.
FREDERIC S. LEE.
COLUMBIA UNIVERSITY,
June 1,
1915.
CONTENTS
PAGE
PREFATORY
NOTE v
EDITORIAL
NOTE
vii
ILLUSTRATIONS
xi
CHAPTER I
HARVEY'S ATTITUDE TOWARD THE QUESTION OF THE
USE OF
THE
CIRCULATION 1
CHAPTER
II
THE CIRCULATION AND THE FEEDING OF THE TISSUES
7
CHAPTER III
RESPIRATION AND THE
CIRCULATION 11
CHAPTER IV
THE
CIRCULATION AND THE ARISTOTELIAN PRIMACY OF
THE
HEART 42
CHAPTER
V
PHYSICIANS _versus_ PHILOSOPHERS--HARVEY FOR
THE
PHILOSOPHERS 55
CHAPTER
VI
THE CIRCULATION AND THE PRIMACY OF THE
BLOOD 64
CHAPTER VII
THE CAUSE OF THE
HEART-BEAT 79
CHAPTER
VIII
HARVEY'S DELINEATION OF THE VENOUS RETURN
95
CHAPTER IX
THE BLOOD THE SEAT OF THE
SOUL 103
CHAPTER X
THE BLOOD THE
INNATE HEAT 116
CHAPTER XI
THE
INNATE HEAT NOT DERIVED FROM ELEMENTAL FIRE 139
CHAPTER
XII
THE CIRCULATION OF THE BLOOD AND THE CIRCULATION
OF THE
HEAVENS
154
NOTES 159
INDEX 191
ILLUSTRATIONS
Portrait
of William Harvey by Cornelius Jonson
_Frontispiece_
FACING PAGE
The Anatomical Theater at
Padua 2
Page 80, right, of Harvey's
_Prelectiones_,
with
transcript 42
The
Title-page of the _Editio Princeps_ of Harvey's
_De Motu
Cordis_ 96
HARVEY'S
VIEWS ON THE USE OF THE CIRCULATION OF THE BLOOD
CHAPTER
I
HARVEY'S ATTITUDE TOWARD THE QUESTION OF THE USE OF THE
CIRCULATION
It is a happy moment for a physiologist when the train
which is
bearing him across the luxuriant plain of Venetia stops at the
cry
of "Padova!" If he have not informed himself too thoroughly about
the
sights which he will see at the Paduan University, he will enjoy
his own
surprise when he is ushered into the Anatomical Theater of
Fabricius ab
Aquapendente--a room in which standing-places rise
steeply, tier above tier,
entirely around a small central oval pit.
Looking down into this, as he leans
upon the rail, the traveler
will realize with sudden pleasure that William
Harvey, when a
medical student, may often have leaned upon the self-same rail
to
see Fabricius demonstrate the anatomy of man. The place looks fit
to
have been a nursery of object-teachers, for it is too small
to hold a pompous
_cathedra_; and the veteran to whose Latin the
young Englishman listened must
have stood directly beside the dead
body. To an American, musing there alone,
the closing years of the
sixteenth century, the last years of Queen Elizabeth
of England,
which seem so remote to him when at home, are but as
yesterday.
Recent, indeed, in the history of medicine is the year 1602,
when
Harvey received his doctor's degree at Padua and returned to
London;
but for all that we are right in feeling that our day is far
removed
from his. The tireless progress of modern times has swept on
at
the charging pace; but in Harvey's time books were still a living
force
which had been written in days five and six times as far
removed from the
student of Padua as he from us. Galen, the Greek
who practised medicine at
imperial Rome in the second century of the
Christian era; Aristotle, who had
been the tutor of Alexander the
Great five hundred years before Galen, when
Rome was but a petty
state warring with her Italian neighbors;--these
ancients were still
great working authorities in Harvey's day.[1]
It
is against this persistent glow of the Greek thought that
Harvey stands out
so vividly as the first great modern figure in
physiology. But it rather
heightens than lowers his achievement that
it was by the ancient glow that he
saw his way forward, admiring the
past, but not dazzled by it. In his old age
he bade a young student
"goe to the fountain head and read Aristotle, Cicero,
Avicenna";
and in talk with the same youth Harvey called the moderns by a
name
so roughly contemptuous that it will not bear repeating.[2] Yet
in
his old age, in the very act of extolling the ancients, he wrote
as
follows:[3]--
"But while we acquiesce in their discoveries,
and believe, such
is our sloth, that nothing further can be found out,
the lively
acuteness of our genius languishes and we put out the
torch
which they have handed on to us."
[Illustration: The
Anatomical Theatre at Padua, where William Harvey
listened to the lectures of
Fabricius ab Aquapendente.]
It was in 1628, the year of his fiftieth
birthday, that Harvey
published, at Frankfort-on-the-Main, his famous Latin
treatise
entitled: "An Anatomical Exercise on the Motion of the Heart
and
Blood in Animals." A reader of to-day will be inclined to skim
rapidly
over the Introduction to this treatise and over much in
the last three
chapters; and probably he will take only a languid
interest in the two brief
Latin treatises which Harvey published in
defense of the circulation, after
more than twenty years of silence,
in his seventy-first year, at Cambridge in
1649; these treatises
being entitled: "Two Anatomical Exercises on the
Circulation of the
Blood, to Johannes Riolanus, Junior, of Paris."
The
demonstration of the circulation in the treatise of 1628 is so
irresistible
that the ancient strongholds of belief crash to the
ground at that summons
like the walls of Jericho, and it seems a
waste of time to scan the
fragments. But for all that, the edifice
which had stood for more than
thirteen centuries was a goodly
structure; and whoever shall have read
Aristotle and Galen at first
hand and shall then return to Harvey, will read
with interest what
the same reader treated as a mere foil for the great
demonstration;
and will realize that the irresistible quality of the latter
is
shared by Galen's demonstration that blood is naturally contained
in
the arteries.[4] Moreover, it will be seen that if the Greek of
the second
century could, like Harvey, appeal to observation and
experiment, the English
physician of the Renaissance, the student
of Cambridge and Padua, was an apt
pupil of the Greeks. Harvey
could, and frequently and naturally did, view
things from a Greek
and ancient standpoint when proof of their nature was
unattainable.
This is to be seen not only in his earlier and later exercises
on
the circulation, but also in his last work, his "Exercise on
the
Generation of Animals" with appended essays, published in Latin
at
London in 1652, in Harvey's seventy-third year, two years
after the
appearance of the exercises addressed to Riolanus. This
treatise On
Generation deals also at various points with the blood
and the circulation,
as do in addition Harvey's published Latin
letters. We shall find, too, the
same leaning upon the ancients
as immediate precursors in thinking, if we
turn back from the
publications of Harvey's old age to the very first written
words
of his which we possess, private lecture notes jotted down by him
in
his thirty-seventh year for use in 1616--notes happily printed
and published
in 1886.[1] In these notes, written more than eleven
years before the
publication of his most famous treatise, he sets
forth for the first time,
though briefly, the circulation of the
blood, that physiological truth which
to my mind is completely
and indisputably Harvey's own discovery. It is with
Harvey as the
interpreter, not the maker, of this discovery, that I shall
venture
to deal in this paper.
In his old age the great discoverer
recorded his own attitude, as an
interpreter, in the following
words:--
"That freedom which I freely concede to others, I demand
with
good right for myself also; liberty, that is, in dealing
with
obscure matters, to bring forward, to represent, the truth,
that
which seems probable, until the falsity thereof shall clearly
be
established."[5]
In 1636, eight years after he had published
the treatise which now
seems so convincing, Harvey was in Nuremberg and wrote
to Caspar
Hofmann, M.D., a professor of repute who lived there, offering
to
demonstrate the circulation to him. In his letter Harvey
quotes
impatient words of his German colleague, which show that in the
face
of proof the circulation still seemed to some men of high
standing
too useless to be true. Harvey says to Hofmann:--
"You
have been pleased to reproach me rhetorically and chastise
me tacitly as
one who seems to you 'to accuse and condemn nature
of folly as well as
error, and to impose the character of a
most stupid and lazy craftsman
on her, since he would permit
the blood to relapse into rawness and to
return repeatedly to
the heart to be concocted again; and, as often, to
the body at
large to become raw again; and would permit nature to ruin
the
made and perfected blood in order that she may have something
to
do.'"[6]
To this attack Harvey calmly rejoins as follows,
speaking of the
blood:--
"As to its concoction and the causes of
this its motion and
circulation, especially their final cause, I have
said nothing,
indeed have put the subject by entirely and deliberately;
as you
will find set down in plain words and otherwise if you will
be
pleased to read again chapters VIII and IX."[7]
More than
twelve years later still, in defending the circulation
against Riolanus,
Harvey finds it necessary to say:--
"Those who repudiate the
circulation because they see neither
the efficient nor the final cause
of it, and who exclaim '_Cui
bono?_'--(As to which I have brought
forward nothing so far;
it remains to be shown)--plainly ought to
inquire as to its
existence before inquiring why it exists; for from the
facts
which meet us in the circulation regarded as existing, its
uses
and objects are to be sought."[8]
In spite, however, of
these disclaimers of formal position Harvey
had repeatedly intimated, by the
way, what was crossing his mind
as to the meaning of the circulation, to set
forth the proofs of
which had been his main concern. Even in the eighth
chapter to which
Harvey appealed in support of his disclaimer Hofmann could
have
pointed to two passages as affording from his standpoint a basis
for
his attack. In the second and shorter of these two passages
Harvey
says of a vein as compared with an artery:--
"This is a
way from the heart, that to the heart; that contains
cruder blood,
effete and rendered unfit for nutrition; this,
concocted, perfect,
alimentary blood."[9]
Harvey, indeed, as we shall find abundant evidence,
was both an
observer and a speculator. In the latter role he was not far
removed
from his physiological predecessors of two thousand years; as
an
observer it was his great merit to lead the physiologists of his
time
and to point out to those of all later centuries the path which
they must
follow.
CHAPTER II
THE CIRCULATION AND THE FEEDING OF
THE TISSUES
That Harvey frequently took refuge in speculation need
excite no
surprise. In the seventeenth century, even with his
extraordinary
contributions of observed fact to the knowledge of the
circulation
of the blood, the paucity of physiological knowledge in general
and
of experimental methods was so great that at every turn a thinking
man
was tempted to fill in the gaps with that which was beyond his
powers of
ocular demonstration. Contemplation of the circulation,
indeed, led Harvey
into contemplation of widely diverse problems of
the life process. The
feeding of the tissues, the significance of
respiration, the cause of the
heart-beat, the relative importance of
the heart and the blood in the bodily
hierarchy, the bodily heat and
its source, and the seat of the soul--to these
and other topics he
gave much attention, and these we must consider. Let us
begin with
the circulation and its relation to the feeding of the
tissues.
In the chapter of Harvey's book which follows at once upon the
brief
qualitative statement quoted at the end of our last chapter,
Harvey
himself brings us face to face with the difficult
quantitative
question raised by his triumphant proof of the circulation.
He
says:--
"The blood under the influence of the arterial pulse
enters and
is impelled in a continuous, equable, and incessant stream
into
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."[10]
Here we see that the rapid renewal of
the blood in "every part and
member of the body" presented itself to Harvey's
own mind as calling
for some other explanation than the simple feeding of the
tissues.
The question of "_cui bono_" which his discovery raised is still
but
incompletely answered; in Harvey's day it was almost unanswerable.
In
dealing from time to time with its main features he himself, as
we shall see,
could only bring forward inadequate observations and
shift his ground from
one erroneous doctrine to another. In justice
to his opponents, who seem to
us so unreasonable, let us remember
how prodigious this new question of "_cui
bono_" must have seemed
when the circulation itself was a novelty. Let us
remember also
that for nearly two thousand years the tissues had been held
to
feed themselves tranquilly out of the contents of the vessels in a
way
fitly expressed by the old simile of irrigation ditches in a
garden--a simile
which Aristotle and Galen had borrowed in turn from
Plato.[11]
But if
Harvey saw only too well that the feeding of the tissues
could not explain
the circulation, he had at least seen plainly how
the doctrine of the
circulation clarified the ancient but current
doctrine as to the absorption
of the digested food. The portal
vein had been accepted as the route of this
absorption. No doubt
both Aristotle and Galen had seen its ruddy contents; at
any rate
both had concluded that the chyle was changed within the
portal
vein into a crude approximation to blood.[12] That the same
vessel
should carry to the liver altered chyle, and from the liver
blood
to nourish the stomach and intestines, had involved a
difficulty
which Galen had met with characteristic cleverness. He had
cited
in support of such a reversal of flow the flow of the bile into
the
gall-bladder and out by the same duct, the movement of food
and vomit into
and out of the stomach by the œsophagus, and the
relation of the _os uteri_
to impregnation and parturition.[13]
Harvey says:--
"For the
blood entering the mesentery by the cœliac
artery and the superior and
inferior mesenteries proceeds
to the intestines, from which along with
the chyle that has
been attracted into the veins it returns by their
numerous
ramifications into the vena portæ of the liver, and
from
this into the vena cava, and this in such wise that the
blood in these veins has the same colour and consistency as
in other
veins, in opposition to what many believe to be
the fact. Nor need we
hold the improbable belief that two
inconveniently opposed movements
take place in the whole
capillary ramification, namely, movement of the
chyle upward,
of the blood downward. Is not the thing rather arranged as
it
is by the consummate providence of nature? For were the chyle
mingled with the blood, the crude with the concocted in equal
proportions, the result would not be concoction, transmutation,
and
sanguification, but rather, because they are reciprocally
active and
passive, a mixture, their union with one another
producing something
intermediate, precisely as when wine is
mixed with water and [in]
vinegar and water [oxicratum]. But
when a minute quantity of chyle is
mingled with a large quantity
of blood flowing by, a quantity of chyle
that bears no notable
proportion to the blood, the effect is the same,
as Aristotle
says, as when a drop of water is added to a cask of wine,
or the
contrary; the resulting total is not a mixture, but is
either
wine or water. So in the dissected mesenteric veins we do
not
find chyme or chyle and blood, separate or mingled, but only
blood, sensibly the same in color and consistency as in the rest
of the
veins."[14]
In a second passage of the same chapter,[15] Harvey returns
to this
subject; and again, twenty-one years later, in his first exercise
to
Riolanus, as follows:--
"Our learned author mentions a certain
tract of his on the
Circulation of the Blood: I wish I could obtain a
sight of it;
perhaps I might retract. But had the learned writer been
so
disposed, I do not see but that, having admitted the circular
motion of the blood (and in the veins, as he says in the
eighth chapter
of the third book,[16] the blood incessantly
and naturally ascends, or
flows back, to the heart, as in all
the arteries it descends or departs
from the heart), all the
difficulties which were formerly felt in
connection with the
distribution of chyle and the blood by the same
channels are
brought to an equally satisfactory solution; for all the
mooted
difficulties vanish when we cease to suppose two contrary
motions at once in the same vessels, and admit but one and
the same
continuous motion in the mesenteric vessels from the
intestines to the
liver."[17]
From this passage we see, in passing, that Harvey at the age
of
seventy made little account of Caspar Aselli's discovery of
the
lacteals, published twenty-two years before in 1627,[18] the
year
before the announcement of the discovery of the circulation.
Harvey's
mind was focused on the blood, its motion and its meaning;
this was to him
the subject of prime importance. The ancient
doctrine of the feeding of the
tissues provided an insufficient
reason for the existence of what his
observations and his
experiments revealed to him.
CHAPTER
III
RESPIRATION AND THE CIRCULATION
So the feeding of the
tissues could not sufficiently account, to
Harvey's mind, for the swiftness
of the circulation. What could?
It is easy for us to recite the multitudinous
modern duties of the
blood as a bearer of cells and of chemicals from point
to point and
as a protector against poisoning; above all it is easy to
exclaim
"respiration";--to read the most striking part of the riddle
by
knowing the answer which was wrung laboriously from Nature after
Harvey
had died. It is easy for us to see that speedy death from
loss of the
circulating blood is practically the same as death
from ligature of the
arteries of the brain, or from drowning,
or strangulation, or a broken neck.
But this was veiled from
him, and what best accounts for the volume and
swiftness of the
Harveian circulation was, in Harvey's day, a stumbling block
to its
acceptance; for no adequate reason was apparent why the whole
mass
of the blood should traverse the lungs, or why, if the veins
receive
their blood from the arteries, the venous blood should differ
in
color from the arterial.
Let us remember that throughout Harvey's
life air was still an
elementary body in the eyes of many and, for all, blood
was a quite
mysterious, ruddy, hot, vital liquid. Only weak magnifying
glasses
were available for him, and the powerful lenses of Malpighi and
van
Leeuwenhoek had not yet revealed to the world either capillary
or
blood-corpuscle. Moreover, the gossiping John Aubrey, the man who
had
been advised about his youthful studies by Harvey, wrote of him
some years
after his death, that "he did not care for Chymistrey,
and was wont to speake
against them [the chemists] with an
undervalue."[19] Where would physiology
be to-day, had not histology
and chemistry long stood in the forefront beside
her?
In a passage of the treatise of 1628 Harvey speaks of
respiration,
as follows:--
"And now it has come to this, that it
would seem better worth
while and more straightforward for those who
seek the path by
which in man the blood passes through the vena cava
into the
left ventricle and the venous artery,[20] to be willing
to
search for the truth by dissecting animals, in order to look
for the reason why in the larger and more perfect animals, when
full
grown, nature chooses to make the blood percolate through
the parenchyma
of the lungs rather than take wide open paths as
in all other animals
(it being understood that no other path
and transit can be thought
out):--whether it is because the
larger and more perfect animals are
hotter and when they are
full grown their heat is more ignited, so to
speak, and prone
to be smothered, that there is this permeation and
transfer
through the lungs in order that the heat may be tempered by
the
inspired air and guarded from boiling up and smothering--or
for
some other similar reason. But to determine these matters
and
explain them completely were to enter on a speculation as to
the
purpose for which the lungs are made. About these and their
use
and motion, and the whole subject of ventilation and the
need
and use of air, and other matters of this sort, and about
the
various different organs created in animals by reason
thereof,
although I have made a vast number of observations, I shall
not
speak till I can more conveniently set them forth in a
treatise
apart, lest by wandering at this point too far from my
subject,
which is the motion and use of the heart, I should seem to
deal
with something else and leave my position, to confuse and
evade
the question."[21]
Farther on in the same treatise Harvey
says:--
"Moreover, the reason why the lungs have vessels so ample,
both
vein and artery, that the trunk of the venous artery
exceeds
in size the crural and jugular branches taken both
together;
and the reason why the lungs are so full of blood as we
know
them to be by experience and inspection (heeding
Aristotle's
warning,[22] and not deceived by the inspection of such
lungs as
we have removed from dissected animals from which all the
blood
had flowed out)--the reason is, that in the lungs and
heart
is the storehouse, the source, the treasury of the blood,
the
workshop of its perfection."[23]
So the great Englishman
gropes for a moment or two by the light of
ancient Greek doctrines and puts
the question of respiration by. But
this very attitude shows Harvey's thought
to be in such contrast
with the thought of to-day that in order to understand
him we need
to learn more fully his views of respiration; and we find
with
satisfaction that in his lecture notes of more than eleven
years
before he had not put this question by, for he had been called
upon
to lecture upon the uses of the lungs. We must seek in his
lecture
notes, therefore, for what he had thought those uses to be.
These
notes, however, we shall be unable to follow unless now, first
of
all, we shall give the floor for a while to the ancients; for
from
their doctrines Harvey necessarily took his cue, like the
other
thinkers of his time.
The momentous physiological facts that the
living body of man,
beast, or bird, is warm of itself and that its cooling
means its
death, must always have struck and impressed the human mind,
whether
trained or untrained. More than nineteen centuries before
Harvey
certain thoughts of Aristotle were recorded as follows:--
"In animals all the parts and the entire body possess a certain
innate
natural heat; wherefore they are sensibly warm when
living, the reverse
when making an end and parting with life.
In the animals which have
blood the origin of this heat is
necessarily in the heart, in the
bloodless kinds in the analogue
thereof; for all work up and concoct the
nourishment by means of
the natural heat, the master part most of all.
Life persists,
therefore, when the other parts are chilled; but if
what
resides in this one be so affected total destruction
ensues,
because upon this part they all depend as the source of
their
heat, the soul being as it were afire within this part;
that
is, within the heart in the animals which have blood, in
the
bloodless kinds in the analogue thereof. Necessarily,
therefore,
the existence of life is coupled with the preservation of
the
heat aforesaid, and what is called death is the destruction
thereof."[24]
This heat which is innate in all living animals was styled
by
Aristotle not only "innate" but "natural," "vital,"[25]
and
"physical,"[26] it being indispensable to life and to the working
of
the soul. He held the continued existence of the innate heat to
depend upon
conditions similar to those under which a fire is kept
alive, viz.:
protection both from burning out and from extinction
due to external forces.
Yet the true nature of combustion was not
settled till more than a century
after Harvey's death. The fact
that air is necessary to fire must always have
been a matter of
common knowledge. Therefore, the views of the relations of
air to
fire maintained by Aristotle nearly twenty-one centuries before
the
discovery of oxygen did not seem naive to Harvey, whatever they
may
seem to us. Aristotle held that air exerts upon fire a cooling
influence
which saves it from burning out too fast; and that the
same influence is
exerted upon the vital innate heat of animals
by the air which they breathe
in, or the water which bathes their
gills.[27] Moreover, Aristotle
says:--
"Why those animals breathe most which have lungs
containing
blood, is plain from this: that the warmer an animal is,
the
greater need it has of cooling, while at the same time the
breath passes easily toward the source of warmth within the
heart. But
the way in which the heart is pierced through toward
the lung must be
studied from dissections and from the history
of animals which I have
written. In general terms, then, it is
the nature of animals to need
cooling on account of the firing
of the soul within the
heart."[28]
In the treatise styled the "History of Animals," to which he
refers
us, Aristotle says:--
"There are also channels from the
heart which lead into the lung
and divide in the same way as the
windpipe, and they accompany
the channels from the windpipe throughout
the entire lung. The
channels from the heart lie uppermost; but no
common channel
exists, for it is by contact[29] that they receive the
breath
and transmit it to the heart."[30]
The collection of
ancient Greek commonly called the "Works of
Hippocrates" is judged to be of
the fifth and fourth centuries B.C.
There is included in this collection a
brief treatise on the heart;
and in this occurs the earliest known account of
the structure and
use of the semilunar valves, which together with the rest
of the
cardiac valves were unknown to Aristotle. In the same
Hippocratic
treatise the doctrine is adhered to of the entrance of air into
the
heart for cooling purposes, both the right and the left
ventricle
being specified as receiving it. The author says:--
"The vessel which leads out of the right ventricle ... closes
toward the
heart, but closes imperfectly, in order that air may
enter, though not
very much."[31]
This piece of incorrect physiology may well have received
support
from the fact that the pulmonary semilunar valve is commonly
found
to be not quite competent when the dead and dissected
pulmonary
artery of the bullock is distended with water--an observation
which
the ancient author intimates that he has made,[32] though he
does
not specify the creature dissected.
Nearly five hundred years
after the death of Aristotle, the analogy
between life and flame was
discussed, formally and at some length,
by Galen. He knew his Aristotle well,
and agreed with him as to the
importance of respiratory cooling for
protracting the indispensable
heat of animals.[33] But we find Galen dealing
with the uses of
respiration in a less simple way than Aristotle. In a
polemical
treatise Galen debates the question whether "the breath drawn
in
in respiration" actually enters the heart, or whether it cools
it
without entering it. He says:--
"It is possible that the whole
is breathed out again, as was
believed by most physicians and
philosophers, and those the
keenest, who say that the heart, while it
craves to be cooled,
is in need not of the substance, but of the
quality[34] of the
breath, and that the use of respiration is indicated
by the
part.... I have shown in my treatise on the use of
respiration
that either an absolutely minute quantity, or none at all,
of
the substance of the air, is taken into the heart."[35]
It is
clear, however, that Galen, when delivering himself of the
foregoing, was a
trifle carried away by the ardor of contention; for
in the very treatise to
which he refers us, as well as elsewhere,
he not only dilates upon the
cooling effects of breathing,
but admits the entrance of air into the heart
for a definite
physiological purpose. This purpose, however, which we shall
study
later, is not cooling and is counted of secondary importance
by
Galen. Nevertheless, he goes so far as to say this:--
"That
some portion of the air is drawn into the heart in its
diastole and
fills the vacuum which is produced, is sufficiently
shown by the very
magnitude of the dilation."[36]
In his treatise "On the Use of the Parts
of the Human Body" Galen
takes a more judicial tone in the following brief,
calm summary:--
"The use of the respiration of animals arises from
the heart,
as has been shown. The heart itself needs in some sort
the
substance of the air; but, first and foremost, it craves to
be cooled, because it boils with heat. The heart is cooled by
the cool
quality of inspiration; but expiration also cools, by
pouring out that
which seethes within the heart and is, in a
way, burned up and
sooty."[37]
Thus do we see the modern products of respiration
foreshadowed.
Galen believed that the heat of animals is safeguarded also
by the
entrance of cooling air through the pores of the skin into
the
arterial system, and by the exit through these pores of
injurious
fumes out of the arteries.[38] In the introduction to Harvey's
great
treatise of 1628[39] the English physician riddles with
adverse
arguments this doctrine of Galen; to this we shall return later,
as
we shall to Galen's belief that the brain draws cooling air
directly
into its ventricles out of the nares through the cribriform plate
of
the ethmoid bone.[40]
In passing from Aristotle to Galen we have
crossed nearly five
centuries. Now let us pass at a leap across fourteen
centuries
more, from Galen at imperial Rome under Septimius Severus to
Harvey
at London under King James the First. Having briefly scanned
the
doctrines of the Greeks, let us take up our study of respiration
in
Harvey's private lecture notes of 1616. His crabbed handwriting
has been
deciphered by experts, and his notes have been both
photographed and printed.
If we seek therein for his thoughts about
respiration, and track them through
the jungle of abbreviated
careless Latin and racy English in which they were
jotted down, we
shall find them Galenic in part, but also denying a truth
which
Galen had accepted. Harvey's notes are often too disconnected
for
quotation, calling rather for paraphrase or summary; and to
make
either is a task which one cannot approach without
diffidence,
especially as this task involves translation also. Of what I
have
ventured to prepare to represent parts of Harvey's note-book in
the
present paper some passages are simple translations, such
English
words as Harvey interspersed being transcribed. Naturally
such
passages are included between quotation marks. These are not
used,
however, in the case of a paraphrase or summary, even if it
contains
scattered English words which are Harvey's own.
Harvey fully
shared the ancient view of the supreme importance
of the heat of animals. In
his note-book he, like Galen, deals
with respiration under the heads: first,
of a possible absorption
of some of the substance of the air; and, second, of
cooling and
ventilation. Let us first take up the second head. Harvey
says:--
"Without nourishment life cannot be, nor nourishment
without
concoction, nor concoction without heat, nor heat
without
ventilation;" for heat perishes either of wasting or of
smothering; "so there is cooling and ventilation of the native
heat,
ventilation especially."[41]
His words contain reminders of
Aristotle;[24] and he continues about
respiration in a vein as ancient as
Hippocrates,[42] as follows:--
"Nothing is so necessary, neither
sense nor food. Life and
respiration are convertible terms, for there is
no life without
breathing and no breathing without life. If the eye be
cut out
there is an end of seeing; if the legs be cut off there
is
an end of walking; if the tongue, of speech, _et cetera_; if
respiration, there is an end of everything immediately."[43]
When Harvey
jotted this down he had in mind a Galenic passage which
doubtless had become
the common property of all physicians in his
day; for the removal of eye and
legs figures in the first chapter of
Galen "On the Use of Respiration."[44]
Harvey continues:--
"Hence large animals are much warmer and breathe
frequently,
because they have need of greater cooling and
ventilation
inasmuch as they very greatly abound in blood and
heat."[45]
In the margin opposite this passage there is
written:--
"Why and how air is needed by animals which breathe and
also air
is necessary to a candle and to fire see W. H."
We may
conjecture that this note refers to Harvey's promised
treatise on
respiration, which was never published.
So far Harvey has simply
reiterated the ancient doctrine of cooling
and ventilation, as in the
passages quoted previously from the
treatise of 1628. We shall find it very
interesting to see how he
deals with the other ancient doctrine that some of
the substance
of the air joins the blood in respiration. That this is true,
gas
analysis and the mercurial air-pump have taught us; but in this
matter
modern demonstration does but confirm, extend, and make
precise one of the
oldest of physiological beliefs. Regarding this
we must now give the floor
once again to the ancients, in order to make Harvey comprehensible. |
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