Page:The Works of William Harvey (part 1 of 2).djvu/64

lx liver, whence, by its ramifications, it carries the blood that is requisite to nourish and maintain every part of the body.

This of itself is enough. But when, in addition, we find that Columbus denies the muscular nature of the heart, we are fully qualified to form a true estimate of the conception which he could have had of the motion of the blood, and of his right to be regarded as the discoverer of its ceaseless circular movement.

The next who is brought upon the scene with the imputed honour of having had a knowledge, not only of the lesser, but of the greater or systemic circulation also, is Andreas Cæsalpinus, of Arezzo. The account which this celebrated peripatetic philosopher gives of the passage of the blood from the right to the left side of the heart is essentially the same as that given by Columbus. From the right ventricle the blood passes into the pulmonic artery, and from this, by numerous anastomoses, into the pulmonic veins, which transmit it to the left ventricle. Cæsalpinus says well that it is absurd to call the pulmonary artery by the name of vena arteriosa, on the mere ground of its taking its departure, like the vena cava, from the right ventricle; it is a true artery, and is, in all respects, analogous to the aorta. The title of arteria venosa, again, given to the pulmonic vein is not less ridiculous; inasmuch as this vessel, though it end in the left ventricle, has all the properties of the veins at large.

So far it looks as if Cæsalpinus had an exact idea of the pulmonary circulation; indeed, he uses the word Circulation in reference to the transit of the blood through the lungs; but when we discover him still speaking of the permeation of the septum ventriculorum by the blood, our faith in the extent and accuracy of his knowledge begins to waver.

With reference to the greater or systemic circulation, again,