HARVEY. 89 



into them, being filled like sacs or bladders, and not ex- 

 panding like bellows. These conclusions are confirmed 

 by the jerking way in which blood flows from a cut 

 artery. 



In the heart itself two distinct motions are observed 

 first of the auricles, and then of the ventricles. These 

 alternate contractions and dilatations can have but one 

 result, namely, to force the blood from the auricle to the 

 ventricle, and from the ventricle, on the right side, by 

 the pulmonary artery to the lungs, and on the left side 

 by the aorta to the system. 



These considerations suggest to the mind of Harvey 

 the idea of the circulation. " I began to think," he 

 says, "whether there might not be a motion, as it were, 

 in a circle." This is next established by proving the 

 three following propositions : 



(1) The blood is incessantly transmitted by the action 



of the heart from the vena cava to the arteries 

 in such quantity that it cannot be supplied from 

 the ingesta, and in such wise that the whole 

 mass must very quickly pass through the organ ; 



(2) The blood, under the influence of the arterial 



pulse, enters, and is impelled in a continuous, 

 equable, and incessant stream through every 

 part and member of the body, in much larger 

 quantity than were sufficient for nutrition, or 

 than the whole mass of fluids could supply ; 



