An anatomical disquisition on the motion of the heart & blood in animalsHarvey, William
Science
An anatomical disquisition on the motion of the heart & blood in animals
Harvey, William
Blood -- Circulation
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.
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