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....

"Toward the end of the fourth day and the beginning of the fifth
the sanguineous point is already increased in size and is seen
to be turned into a small and very delicate vesicle containing
blood within itself; which blood it drives out at every
contraction, and receives afresh when its diastole takes place.

"Up to this stage I have found it impossible to discriminate
between the vessels; for the arteries are not to be
distinguished from the veins either by their coats or by
the pulse; and so I think it best to style all the vessels,
indiscriminately, veins or, with Aristotle,[186] venous
canals....[187]

"On the sixth day ... the parenchyma of the heart grows on to
the pulsating vesicle; and shortly afterward the rudiments of
the liver and of the lungs are discernible."[188]

It is clear that Harvey's hens did not very often take such well-timed steps against Aristotle; for in another passage of his treatise on generation, in summing up its events and their order, he frankly states the difficulties which render uncertain the question of priority between the blood and the heart. He speaks of "the first generated and generative part; that is to say, the blood together with its receptacles or, if you prefer, the heart with its veins."[189] A few lines further on he says:--

"In the generation of this first part (which is accomplished
in the egg on the fourth day) although I have not been able to
observe any order, because all portions of the part aforesaid
(namely, the blood, the veins and the pulsating vesicle) appear
at the same time; nevertheless, my belief would be, as I have
said, that the blood is present before the pulse; and that,
therefore, in obedience to a law of nature the blood is prior to
its receptacles, that is, to the veins."[190]

In Harvey's first publication, of 1628, we have read:--

"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."[191]

In his last publication, of 1651, we have read:--

"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."[192]

Harvey's own words in the foregoing two passages effectively sum up both the nature of his doctrine that the blood is the first part of the body to live, and the nature of his evidence. But the words of the second passage foreshadow a closely related doctrine, advanced and held by him on the evidence of observation, viz.: that the blood, being the first part to live, is also the last part of the body to die. That the first part to live is always the last to die, is a doctrine set forth by Aristotle. This, Harvey seems to accept without question and to apply upon proper evidence to the blood; as he accepts and warmly upholds the ancient master's doctrine that there is a primacy of the body. The results of observation have forced Harvey to transfer this primacy from the heart to the blood, but it is the Aristotelian primacy still. Presently he shall show us that the blood is not only the first part to live, but the last to die. Before he does so, however, let Aristotle speak for himself, saying briefly:--

"The point[193] of origin [of the rest of the body] is the
first thing generated. The point of origin in the animals which
possess blood is the heart; in the rest, the analogue thereof,
as I have often said. Moreover, the fact that the heart is the
first thing generated is evident, not only to the senses, but
from its death.[194] For therein life ceases the last; and in
all cases the last generated is the first to make an end, the
first generated, the last to make an end; nature, as it were,
doubling back and returning upon her point of origin whence
she came.[195] For generation is the change from not being to
being; destruction is the reverse change, from being to not
being."[196]

Aristotle does not tell us why "in all cases ... the first generated" is "the last to make an end," and _vice versa_. Let it suffice that Harvey accepts this sweeping doctrine. Now let him complete his evidence in favor of the primacy of the blood by showing that the blood is not only the first part to live and to live tenaciously, but the last part to die.

In a passage of the treatise On the Motion of the Heart and Blood, we have already read Harvey's promise to publish observations

"on the formation of the fœtus, where numerous problems of
the following order can find a place: Why should this part 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]

That Harvey should have printed this passage in 1628, in the same work with his repeated eulogies of the Aristotelian heart, shows that the idea of the possible primacy of the blood must have been in his mind early. It was, indeed, so from the jotting down of his private notes of 1616, to the publication of the Exercises to Riolanus in 1649 and the treatise On Generation in 1651. The same mental attitude is revealed, perhaps more strongly, in the following passage of an earlier chapter of Harvey's treatise of 1628. Here we come upon the thought that it may be the blood, and neither ventricle nor auricle, which is the last to die. Harvey says:--

"Besides this, however, I have occasionally observed, after
the heart and even its right auricle[197] had ceased their
pulsations as though in the act of dying, that an obscure
motion and flow and a sort of palpitation manifestly remained
in the blood itself contained in the right auricle, so long,
that is, as the blood appeared to be imbued with heat and
spirits. Something of the sort is very plainly to be seen at
the beginning of the generation of an animal, in the hen's egg
within the first seven days of incubation. There is present,
first and before all else, a drop of blood which palpitates (as
Aristotle also noted); from which, when growth has taken place
and the chick has been formed to some extent, the auricles of
the heart are made; and in these, which pulsate perpetually,
life inheres....

"Whoever, therefore, shall choose to investigate more closely
will say that the heart is not the first to live and the last to
die, but that the auricles, and the part which answers thereto
in serpents, fishes, and such animals, are alive sooner than the
heart itself and also die later than the heart. Whether even
earlier the blood itself, or the spirit, have not an obscure
palpitation of its own, which it has seemed to me to retain
after death, may well be questioned; and whether we should not
speak of life as beginning with palpitation."[198]

It is plain that fibrillar contractions of cardiac muscle misled Harvey into thinking and writing of "an obscure motion and flow," of "an obscure palpitation," of the blood itself within the dying auricle. It is plain that when he wrote his most famous treatise he was loath, even under Aristotle's leadership, to reach out so far beyond the evidence of the senses as to attribute the palpitation of the visible drop of blood in the very early embryo to anything but the hot blood itself. Later, in his treatise On Generation, he published a passage which in some ways runs parallel with the foregoing. In the earlier passage the results of observation are brought forward as food for thought; in the later one, as proofs of a theory, fully, clearly, and emphatically stated by a thinker who is near the end of life and is imparting his final judgment. This later passage is as follows:--

"In whatsoever part of the body heat and motion have their
beginning, in that same part life also first arises and therein
is extinguished last; nor may it be doubted that there, too,
life has its innermost home, that there the soul itself has
fixed its seat.

"The life then inheres in the blood (as we read also in Holy
Writ[199]), because therein the life and the soul are manifest
first and fail last. For, as I have said, in the dissection of
living animals I have found repeatedly that, though the animal
be dying and breathe no longer, nevertheless, the heart pulsates
for some time and keeps the life in it. Moreover, when the heart
is quieted you may see movement surviving in the auricles, and
latest in the right auricle; and at length all pulsation ceasing
there, you may find in the blood itself a kind of undulation and
obscure agitation or palpitation, the last indication of life.
And anyone can perceive that the blood retains in itself to the
last the heat which is the author of pulsation and life; if this
heat is once wholly extinguished and the blood now is blood
no more, but cruor, so there is left no hope of a return to
life again. Nevertheless, after all pulsation has disappeared,
both in the egg, as I have said, and in dying animals, if you
will make a gentle warm application, in the former case to the
leaping point, in the latter to the right auricle of the heart,
you shall see movement, pulsation, and life, renewed immediately
by the blood; provided it have not utterly lost all its innate
heat and vital spirits."[200]

How readily heat from without can revive the cool leaping point, is strikingly set forth by Harvey in another chapter of this treatise On Generation. He says:--

"Moreover, if an egg be exposed too long to a colder atmosphere,
its leaping point pulsates less often and stirs more languidly;
but if a warm finger be applied to it, or any other bland source
of warmth, straightway it recovers strength and vigor. Indeed,
when such a point has become gradually weak and though full of
blood ceases to move at all and gives no sign of life, seeming
utterly to have succumbed to death, if my lukewarm finger be
placed over it for the space of twenty pulsations of my artery,
behold! the little heart revives once more, becomes erect, and
renews its pristine dance as though come back from Hades. This
I myself and others, too, have brought about again and again by
means of gentle warmth of any kind, such as that of a fire or of
tepid water; thus at our pleasure being able to give over the
poor little soul to death, or call it back to the light."[201]

As in the embryo the leaping point may be revived by external warmth, so may the heart in the full-grown bird. In his treatise of 1628 Harvey says:--

"In the pigeon, at any rate, at an actual experiment, after the
heart had wholly ceased to move and even the auricles had left
off moving, I placed my finger, wetted with saliva and warm,
upon the heart and kept it there for a while; as the result of
which fomentation the heart, as though restored to strength and
life again, and its auricles with it, were seen to move and
contract and relax themselves and, as it were, to be recalled
from death."[202]

In his treatise On Generation, Harvey confirms the doctrine of the primacy of the blood by citing observations made upon sluggish or hibernating animals and also certain morbid phenomena in man, as follows:--

"This, too, clearly follows from many observations; especially
the cases of certain animals which possess blood yet live a long
time without a pulse; and of some which lie hidden the whole
winter and, nevertheless, continue alive, although meanwhile all
movement of the heart has ceased and their lungs enjoy a rest
from breathing, like people who lie half dead and pulseless in
syncope or faintness or hysterical affections."[203]

So Harvey convinced himself, by observation, that the first part of the developing embryo to appear is the blood of the "sanguineous lines"; after this the blood which seems to palpitate of itself at the leaping point, which later develops into a pulsating vesicle wherein blood is contained within a contractile wall; to this being superadded still later the contractile parenchyma of the heart. Also, by observation, he convinced himself that in a dying animal the blood within the right auricle may palpitate of itself after the palpitations due to contractions of the auricular wall have ceased. Thus was Harvey led to believe that the blood and not the heart is the first part to live and the last to die, the principal part of the body, the generator of the heart and of all the rest. In spite of his appeal to observation, his impressive primacy of the blood is now as completely forgotten in its turn as is Aristotle's impressive primacy of the heart, which Harvey felt called upon to supersede. Naturally in this matter the great discoverer used true methods of investigation; and doubtless his imperfect conclusions were due in large part to the weakness of his magnifying glasses and to the deficient technique of his day. Harvey said of himself, speaking generally, that he trusted much to the plain use of his senses.[204] That he did so, was well for him and for all mankind; yet because of this very trust he did not always escape the pitfalls dug by what we now call "naked-eye" appearances.