86 FATHERS OF BIOLOGY. 



lesser circulation in the following words : " This com- 

 munication (i.e. between the right and left sides of the 

 heart) does not take place through the partition of the 

 heart, as is generally believed ; but by another admirable 

 contrivance, whereby from the right ventricle the subtle 

 blood is agitated in a lengthened course through the 

 lungs, wherein prepared, it becomes of a crimson colour, 

 and from the vena arterialis (pulmonary artery) is trans- 

 ferred into the arteria venalis (pulmonary vein). Mingled 

 with the inspired air in the arteria venalis, freed by re- 

 spiration from fuliginous matter, and become a suitable 

 home of the vital spirit, it is attracted at length into the 

 left ventricle of the heart by the diastole of the organ." 

 But when Servetus comes to speak of the systemic circu- 

 lation, what he has to say is as old as Galen. 



The opinions, therefore, on the subject of the blood 

 and its distribution which were prevalent at the end of 

 the sixteenth century prove 



(1) That although the blood was not regarded as 



stagnant, yet its circulation, such as is nowa- 

 days recognized, was unknown ; 



(2) That one kind of blood was thought to flow from 



the liver to the right ventricle, and thence to 

 the lungs and general system by the veins, while 

 another kind flowed from the left ventricle to 

 the lungs and general system by the arteries ; 



(3) That the septum of the heart was regarded as 



