HEART AND BLOOD. 41 



a quantity of liquid must take some short time in the concoc- 

 tion : it must pass through the liver ; (it is allowed by all that 

 the juices of the food we consume pass twice through this organ 

 in the course of the day;) it must flow through the veins, 

 through the parenchyma of the kidneys, and through the 

 ureters into the bladder. 



To those, therefore, whom I hear denying that the blood, aye 

 the whole mass of the blood may pass through the substance 

 of the lungs, even as the nutritive juices percolate the liver, 

 asserting such a proposition to be impossible, and by no means 

 to be entertained as credible, I reply, with the poet, that they are 

 of that race of men who, when they will, assent full readily, and 

 when they will not, by no manner of means ; who, when their 

 assent is wanted, fear, and when it is not, fear not to give it. 



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 neces- 

 sary effect of whose impulse is the distension of the vessels and 

 pores of the lungs. And then the lungs, in respiration, are perpe- 

 tually 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 pul- 

 monary vessels ; from the fact of the pulmonary veins and 

 ventricle corresponding with them, being always found to con- 

 tain blood, which must needs have come from the veins, and 

 by no other passage save through the lungs ? Columbus, and 



