Heart and Blood 53 



having a double tunic, extending from it, (Galen is here 

 speaking of the right side of the heart, but I extend his 

 observations to the left side also,) a kind of reservoir 

 had to be provided, to which both belonging, the blood 

 should be drawn in by the one, and sent out by the 

 other." 



This argument Galen adduces for the transit of the 

 blood by the right ventricle from the vena cava into 

 the lungs ; but we can use it with still greater propriety, 

 merely changing the terms, for the passage of the blood 

 from the veins through the heart into the arteries. 

 From Galen, however, that great man, that father of 

 physicians, it clearly appears that the blood passes 

 through the lungs from the pulmonary artery into the 

 minute branches of the pulmonary veins, urged to this 

 both by the pulses of the heart and by the motions of 

 the lungs and thorax; that the heart, moreover, is 

 incessantly receiving and expelling the blood by and 

 from its ventricles, as from a magazine or cistern, and 

 for this end is furnished with four sets of valves, two 

 serving for the induction and two for the eduction of 

 the blood, lest, like the Euripus, it should be incom- 

 modiously sent hither and thither, or flow back into 

 the cavity which it should have quitted, or quit the 

 part where its presence was required, and so the heart 

 be oppressed with labour in vain, and the office of the 

 lungs be interfered with. 1 Finally, our position that 

 the blood is continually passing from the right to the 

 left ventricle, from the vena cava into the aorta, through 

 the porous structure of the lungs, plainly appears from 

 this, that since the blood is incessantly sent from the 

 right ventricle into the lungs by the pulmonary artery, 

 and in like manner is incessantly drawn from the lungs 

 into the left ventricle, as appears from what precedes 

 and the position of the valves, it cannot do otherwise 



1 See the Commentary of the leaned Hofmann upon the Sixth Book 

 of Galen, " De Usu partium," a work which I first saw after I had 

 written what precedes. 



