Galen had already insisted that some blood passed from the right ventricle to the lungs--enough for their nutrition; but Harvey points out, with Colombo, that from the arrangement of the valves there could be no other view than that with each impulse of the heart blood passes from the right ventricle to the lungs and so to the left side of the heart.

How it passed through the lungs was a problem: probably by a continuous transudation.

In Chapters VIII and IX he deals with the amount of blood passing through the heart from the veins to the arteries.

Let me quote here what he says, as it is of cardinal import: "But what remains to be said upon the quantity and source of the blood which thus passes, is of a character so novel and unheard of that I not only fear injury to myself from the envy of a few, but I tremble lest I have mankind at large for my enemies, so much doth wont and custom become a second nature.

Doctrine once sown strikes deeply its root, and respect for antiquity influences all men.