50 Motion of the 



The parenchyma of the liver is extremely dense, 

 so is that of the kidney ; the lungs, again, are of a 

 much looser texture, and if compared with the kidneys 

 are absolutely spongy. In the liver there is no forcing, 

 no impelling power ; in the lungs the blood is forced 

 on by the pulse of the right ventricle, the necessary 

 effect of whose impulse is the distension of the vessels 

 and pores of the lungs. And then the lungs, in respira- 

 tion, are perpetually rising and falling ; motions, the 

 effect of which must needs be to open and shut the 

 pores and vessels, precisely as in the case of a sponge, 

 and of parts having a spongy structure, when they are 

 alternately compressed and again are suffered to expand. 

 The liver, on the contrary, remains at rest, and is never 

 seen to be dilated and constricted. Lastly, if no one 

 denies the possibility of the whole of the ingested 

 juices passing through the liver, in man, oxen, and the 

 larger animals generally, in order to reach the vena 

 cava, and for this reason, that if nourishment is to 

 go on, these juices must needs get into the veins, and 

 there is no other way but the one indicated, why should 

 not the same arguments be held of avail for the passage 

 of the blood in adults through the lungs ? Why not, 

 with Columbus, that skilful and learned anatomist, 

 maintain and believe the like, from the capacity and 

 structure of the pulmonary vessels ; from the fact of 

 the pulmonary veins and ventricle corresponding with 

 them, being always found to contain blood, which 

 must needs have come from the veins, and by no other 

 passage save through the lungs ? Columbus, and we 

 also, from what precedes, from dissections, and other 

 arguments, conceive the thing to be clear. But as 

 there are some who admit nothing unless upon 

 authority, let them learn that the truth I am contending 

 for can be confirmed from Galen's own words, namely, 

 that not only may the blood be transmitted from the 

 pulmonary artery into the pulmonary veins, then into 

 the left ventricle of the heart, and from thence into the 



