Chapter VIII 



Amount of Blood Passing Through the Heart 



from the Veins to the Arteries^ and the 



Circular Motion of the Blood 



SO FAR we have considered the transfer of blood 

 from the veins to the arteries, and the ways by 

 which it is transmitted and distributed by the 

 heart beat. There may be some who will agree with 

 me on these points because of the authority of Galen 

 or Columbus or the reasons of others. What re- 

 mains to be said on the quantity and source of this 

 transferred blood, is, even if carefully reflected 

 upon, so strange and undreamed of, that not only 

 do I fear danger to myself from the malice of a few, 

 but I dread lest I have all men as enemies, so much 

 does habit or doctrine once absorbed, driving deeply 

 its roots, become second nature, and so much does 

 reverence for antiquity influence all men. But now 

 the die is cast; my hope is in the love of truth and 

 in the integrity of intelligence. 



First I seriously considered in many investiga- 

 tions how much blood might be lost from cutting 

 the arteries in animal experiments. Then I re- 

 flected on the symmetry and size of the vessels 

 entering and leaving the ventricles of the heart, for 



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