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.
Caspar Bauhin and John Riolan, [Footnote: i Bauhin, lib. ii. cap.
II. Riolan. lib. viii, cap. I.] most learned men and skilful
anatomists, inform us that 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:
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 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, when near to death, it ceases to respond by its proper
motion, but seems, as it were, to nod the head, and is so
slightly moved that it appears rather to give signs of motion to
the pulsating auricles 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 that the blood enters the
ventricles, not by any attraction or dilatation of the heart, but
by being 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 its motion in 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,
pulsates 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
and 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, 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 then being 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, etc.,
which both lives before the heart and dies after it.
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 [Footnote: De
Motu Animal., cap. 8.] further remarks, retracing her steps,
reverts to where she had set out, and returns at the end of her
course to the goal whence she had started. As animal generation
proceeds from that which is not animal, entity from nonentity,
so, by a retrograde course, entity, by corruption, is resolved
into nonentity, whence that in animals, which was last created,
fails first and that which was first, fails last.
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 pale-blooded 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 pale-blooded 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 pulsation;
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 whenever 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 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, etc., 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.