HEART AND BLOOD. 45 



tions of vessels. Whence it appears that, although one ven- 

 tricle of the heart, the left to wit, would suffice for the distri- 

 bution of the blood over the body, and its eduction from the 

 vena cava, as indeed is done in those creatures that have no 

 lungs, nature, nevertheless, when she ordained that the same 

 blood should also percolate the lungs, saw herself obliged to 

 add another ventricle, the right, the pulse of which should force 

 the blood from the vena cava through the lungs into the cavity 

 of the left ventricle. In this way, therefore, it may be said that 

 the right ventricle is made for the sake of the lungs, and for the 

 transmission of the blood through them, not for their nutrition ; 

 seeing it were unreasonable to suppose that the lungs required 

 any so much more copious a supply of nutriment, and that of so 

 much purer and more spirituous a kind, as coming immediately 

 from the ventricle of the heart, than either the brain with its 

 peculiarly pure substance, or the eyes with their lustrous and 

 truly admirable structure, or the flesh of the heart itself, which 

 is more commodiously nourished by the coronary artery. 



CHAPTER VIII. 



OF THE QUANTITY OF BLOOD PASSING THROUGH THE HEART 

 FROM THE VEINS TO THE ARTERIES; AND OF THE CIRCULAR 

 MOTION OF THE BLOOD. 



THUS far I have spoken of the passage of the blood from the 

 veins into the arteries, and of the manner in which it is trans- 

 mitted and distributed by the action of the heart; points to which 

 some, moved either by the authority of Galen or Columbus, or 

 the reasonings of others, will give in their adhesion. But what 

 remains to be said upon the quantity and source of the blood which 

 thus passes, is of so novel and unheard-of character, 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, that become as another nature, and doctrine once 

 sown and that hath struck deep root, and respect for antiquity 

 influence all men : Still the die is cast, and my trust is in my 

 love of truth, and the candour that inheres in cultivated minds. 

 And sooth to say, when I surveyed my mass of evidence, whe- 



