Whence it appears that whenever the motion of the
blood through the arteries is impeded, whether it
be by compression or infarction, or interception,
there do the remote divisions of the arteries beat
less forcibly, seeing that the pulse of the arteries
is nothing more than the impulse or shock of the blood
in these vessels.
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.
