Harvey's Views on the Use of the Circulation of the BloodCurtis, John Green
History
Harvey's Views on the Use of the Circulation of the Blood
Curtis, John Green
Blood -- Circulation; Harvey, William, 1578-1657
"Indeed, the passage of the blood into the veins is brought
about by that impulsion and not by any dilatation of the veins
whereby, like bellows, they draw in the blood."[259]
But, despite the foregoing utterances and other such, his statements
are sometimes vague and sometimes quite unexpected, regarding the
nature of the movement of the blood in the veins. Indeed, in 1628 he
speaks quite as a disciple of Aristotle. He says regarding the flow
in the arteries:--
"For this distribution and movement of the blood there is need
of impetus and violence and of an impeller such as the heart.
Partly because the blood readily concentrates and gathers
together of itself--toward its seat of origin, as it were,[260]
or as a part to the whole, or as a drop of the water sprinkled
upon a table to the mass thereof--as the blood habitually
and very speedily does from slight causes, from cold, fear,
horror, and other causes of this sort; partly, also, because
the blood is pressed out of the capillary veins into the small
branches and thence into the greater by the movements of the
limbs and the compression of the muscles; the blood is more
disposed and prone to move from the circumference on the center
than the other way, even supposing no valves to be present as
a hindrance. In order, therefore, to relinquish its seat of
origin, and enter constricted and colder places, and move in
opposition to its bent,[261] the blood has need not only of
violence but of an impeller, such as is the heart alone, and
after the fashion described already."[262]
This picture of the blood hesitating to leave its warm cardiac
birthplace for the chill regions of the periphery, but very ready to
return, has a tone far from hydraulic, but may so much the better
prepare us for the view, made public by Harvey in his old age, that
the blood is the primal seat of the soul itself. Except in the light
of the foregoing passage the following words would be quite obscure.
He says that the auricles
"are filled as being the storehouse and reservoir[263] of the
blood, the blood turning of itself and compressed toward the
center by the movement of the veins."[264]
With due allowance for the use of modes of expression no longer
familiar we find Harvey in 1649 handling the venous flow with
no very modern touch, in the following passage--a passage which
also reminds us that not till twelve years later, four years
after Harvey's death, did Malpighi announce his discovery of the
capillary blood-vessels in the lung of the frog.[265] Harvey says to
Riolanus:--
Public-domain text, read in full here on John Shaqi.
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