OF THE MOTION OF THE HEART AND ITS AURICLES, AS SEEN IN THE BODIES OF
LIVING ANIMALS
Besides the motions already spoken of, we have still to consider those
that appertain to the auricles.
Casper Bauhin and John Riolan,[22] most learned men and skilful
anatomists, inform us from their observations, that if we carefully
watch the movements of the heart in the vivisection of an animal, we
shall perceive four motions distinct in time and in place, two of which
are proper to the auricles, two to the ventricles. With all deference
to such authority I say, that there are four motions distinct in point
of place, but not of time; for the two auricles move together, and so
also do the two ventricles, in such wise that though the places be
four, the times are only two. And this occurs in the following manner:
[22] Bauhin, lib. ii, cap. 21. Riolan, lib. viii, cap. 1.
There are, as it were, two motions going on together: one of the
auricles, another of the ventricles; these by no means taking place
simultaneously, but the motion of the auricles preceding, that of the
heart itself following; the motion appearing to begin from the auricles
and to extend to the ventricles. When all things are becoming languid,
and the heart is dying, as also in fishes and the colder blooded
animals, there is a short pause between these two motions, so that the
heart aroused, as it were, appears to respond to the motion, now more
quickly, now more tardily; and at length, and when near to death, it
ceases to respond by its proper motion, but seems, as it were, to nod
the head, and is so obscurely moved that it appears rather to give
signs of motion to the pulsating auricle, than actually to move. The
heart, therefore, ceases to pulsate sooner than the auricles, so that
the auricles have been said to outlive it, the left ventricle ceasing
to pulsate first of all; then its auricle, next the right ventricle;
and, finally, all the other parts being at rest and dead, as Galen
long since observed, the right auricle still continues to beat; life,
therefore, appears to linger longest in the right auricle. Whilst the
heart is gradually dying, it is sometimes seen to reply, after two or
three contractions of the auricles, roused as it were to action, and
making a single pulsation, slowly, unwillingly, and with an effort.
But this especially is to be noted, that after the heart has ceased
to beat, the auricles however still contracting, a finger placed upon
the ventricles perceives the several pulsations of the auricles,
precisely in the same way and for the same reason, as we have said,
that the pulses of the ventricles are felt in the arteries, to wit,
the distension produced by the jet of blood. And if at this time, the
auricles alone pulsating, the point of the heart be cut off with a
pair of scissors, you will perceive the blood flowing out upon each
contraction of the auricles. Whence it is manifest how the blood enters
the ventricles, not by any attraction or dilatation of the heart, but
thrown into them by the pulses of the auricles.
And here I would observe, that whenever I speak of pulsations as
occurring in the auricles or ventricles, I mean contractions: first
the auricles _contract_, and then and subsequently the heart itself
_contracts_. When the auricles contract they are seen to become whiter,
especially where they contain but little blood; but they are filled as
magazines or reservoirs of the blood, which is tending spontaneously
and, by the motion of the veins, under pressure towards the centre;
the whiteness indicated is most conspicuous towards the extremities or
edges of the auricles at the time of their contractions.
In fishes and frogs, and other animals which have hearts with but
a single ventricle, and for an auricle have a kind of bladder much
distended with blood, at the base of the organ, you may very plainly
perceive this bladder contracting first, and the contraction of the
heart or ventricle following afterwards.
But I think it right to describe what I have observed of an opposite
character: the heart of an eel, of several fishes, and even of some [of
the higher] animals taken out of the body, beats without auricles; nay,
if it be cut in pieces the several parts may still be seen contracting
and relaxing; so that in these creatures the body of the heart may be
seen pulsating, palpitating, after the cessation of all motion in the
auricle. But is not this perchance peculiar to animals more tenacious
of life, whose radical moisture is more glutinous, or fat and sluggish,
and less readily soluble? The same faculty indeed appears in the flesh
of eels, generally, which even when skinned and embowelled, and cut
into pieces, are still seen to move.
Experimenting with a pigeon upon one occasion, after the heart had
wholly ceased to pulsate, and the auricles too had become motionless,
I kept my finger wetted with saliva and warm for a short time upon the
heart, and observed, that under the influence of this fomentation it
recovered new strength and life, so that both ventricles and auricles
pulsated, contracting and relaxing alternately, recalled as it were
from death to life.
Besides this, however, I have occasionally observed, after the heart
and even its right auricle had ceased pulsating,--when it was in
articulo mortis in short,--that an obscure motion, an undulation or
palpitation, remained in the blood itself, which was contained in the
right auricle, this being apparent so long as it was imbued with heat
and spirit. And indeed a circumstance of the same kind is extremely
manifest in the course of the generation of animals, as may be seen in
the course of the first seven days of the incubation of the chick: A
drop of blood makes its appearance which palpitates, as Aristotle had
already observed; from this, when the growth is further advanced and
the chick is fashioned, the auricles of the heart are formed, which
pulsating henceforth give constant signs of life. When at length, and
after the lapse of a few days, the outline of the body begins to be
distinguished, then is the ventricular part of the heart also produced;
but it continues for a time white and apparently bloodless, like the
rest of the animal; neither does it pulsate or give signs of motion. I
have seen a similar condition of the heart in the human foetus about
the beginning of the third month, the heart being then whitish and
bloodless, although its auricles contained a considerable quantity of
purple blood. In the same way in the egg, when the chick was formed and
had increased in size, the heart too increased and acquired ventricles,
which then began to receive and to transmit blood.
And this leads me to remark, that he who inquires very particularly
into this matter will not conclude that the heart, as a whole, is
the primum vivens, ultimum moriens--the first part to live, the last
to die, but rather its auricles, or the part which corresponds to
the auricles in serpents, fishes, &c., which both lives before the
heart[23] and dies after it.
[23] [The reader will observe that Harvey, when he speaks of the
_heart_, always means the ventricles or ventricular portion of the
organ.]
Nay, has not the blood itself or spirit an obscure palpitation inherent
in it, which it has even appeared to me to retain after death? and it
seems very questionable whether or not we are to say that life begins
with the palpitation or beating of the heart. The seminal fluid of
all animals--the prolific spirit, as Aristotle observed, leaves their
body with a bound and like a living thing; and nature in death, as
Aristotle[24] further remarks, retracing her steps, reverts to whence
she had set out, returns at the end of her course to the goal whence
she had started; and as animal generation proceeds from that which is
not animal, entity from non-entity, so, by a retrograde course, entity,
by corruption, is resolved into non-entity; whence that in animals,
which was last created, fails first; and that which was first, fails
last.
[24] De Motu Animal. cap. 8.
I have also observed, that almost all animals have truly a heart, not
the larger creatures only, and those that have red blood, but the
smaller, and [seemingly] bloodless ones also, such as slugs, snails,
scallops, shrimps, crabs, crayfish, and many others; nay, even in
wasps, hornets, and flies, I have, with the aid of a magnifying glass,
and at the upper part of what is called the tail, both seen the heart
pulsating myself, and shown it to many others.
But in the exsanguine tribes the heart pulsates sluggishly and
deliberately, contracting slowly as in animals that are moribund, a
fact that may readily be seen in the snail, whose heart will be found
at the bottom of that orifice in the right side of the body which is
seen to be opened and shut in the course of respiration, and whence
saliva is discharged, the incision being made in the upper aspect of
the body, near the part which corresponds to the liver.
This, however, is to be observed: that in winter and the colder season,
exsanguine animals, such as the snail, show no pulsations; they seem
rather to live after the manner of vegetables, or of those other
productions which are therefore designated plant-animals.
It is also to be noted that all animals which have a heart, have
also auricles, or something analogous to auricles; and further, that
wherever the heart has a double ventricle there are always two auricles
present, but not otherwise. If you turn to the production of the
chick in ovo, however, you will find at first no more than a vesicle
or auricle, or pulsating drop of blood; it is only by and by, when the
development has made some progress, that the heart is fashioned: even
so in certain animals not destined to attain to the highest perfection
in their organization, such as bees, wasps, snails, shrimps, crayfish,
&c., we only find a certain pulsating vesicle, like a sort of red or
white palpitating point, as the beginning or principle of their life.
We have a small shrimp in these countries, which is taken in the Thames
and in the sea, the whole of whose body is transparent; this creature,
placed in a little water, has frequently afforded myself and particular
friends an opportunity of observing the motions of the heart with the
greatest distinctness, the external parts of the body presenting no
obstacle to our view, but the heart being perceived as though it had
been seen through a window.
I have also observed the first rudiments of the chick in the course of
the fourth or fifth day of the incubation, in the guise of a little
cloud, the shell having been removed and the egg immersed in clear
tepid water. In the midst of the cloudlet in question there was a
bloody point so small that it disappeared during the contraction and
escaped the sight, but in the relaxation it reappeared again, red and
like the point of a pin; so that betwixt the visible and invisible,
betwixt being and not being, as it were, it gave by its pulses a kind
of representation of the commencement of life.[25]
[25] [At the period Harvey indicates, a rudimentary auricle and
ventricle exist, but are so transparent that unless with certain
precautions their parietes cannot be seen. The filling and emptying
of them, therefore, give the appearance of a speck of blood
alternately appearing and disappearing.]