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,[85] 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:
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 fœtus 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[86] 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[87] 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.
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.[88]
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.[89]