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
But that the error of Vesalius, and the inexperience of those who
assert their belief that the part below the tube does not pulsate when
the ligature is tied, may be made the more apparent, I can state, after
having made the trial, that the inferior part will continue to pulsate
if the experiment be properly performed; and whilst they say that when
you have undone the ligature the inferior arteries begin again to
pulsate, I maintain that the part below beats less forcibly when the
ligature is untied than it did when the thread was still tight. But the
effusion of blood from the wound confuses everything, and renders the
whole experiment unsatisfactory and nugatory, so that nothing certain
can be shown, by reason, as I have said, of the hemorrhage. But if, as
I know by experience, you lay bare an artery, and control the divided
portion by the pressure of your fingers, you may try many things at
pleasure by which the truth will be made to appear. In the first place,
you will feel the blood coming down in the artery at each pulsation,
and visibly dilating the vessel. You may also at will suffer the blood
to escape, by relaxing the pressure, and leaving a small outlet; and
you will see that it jets out with each stroke, with each contraction
of the heart, and with each dilatation of the artery, as I have said
in speaking of arteriotomy, and the experiment of perforating the
heart. And if you suffer the efflux to go on uninterruptedly, either
from the simple divided artery or from a tube inserted into it, you
will be able to perceive by the sight, and if you apply your hand, by
the touch likewise, every character of the stroke of the heart in the
jet; the rhythm, order, intermission, force, &c., of its pulsations,
all becoming sensible there, no otherwise than would the jets from a
syringe, pushed in succession and with different degrees of force,
received upon the palm of the hand, be obvious to sight and touch. I
have occasionally observed the jet from a divided carotid artery to be
so forcible, that, when received on the hand, the blood rebounded to
the distance of four or five feet.
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