111. 7. 77 



on the right side and the smaller on the left. Not but what 

 there are some ovipara in which this condition is comparatively 

 indistinctly marked ; while on the other hand there are some 

 vivipara in which the liver is manifestly divided into two parts.^ 

 Examples of such division are furnished by the hares of certain 

 regions that have the appearance of having two livers, and by 

 some fishes, especially the cartilaginous kinds.^ 



It is the position of the liver on the right side of the body 

 that is the main cause for the formation of the spleen ; the 

 existence of which thus becomes to a certain extent a matter 

 of necessity in all animals, though not of very stringent necessity. 



The reason, then, why the viscera are bilateral is, as we have 

 said, that there are two sides to the body, a right and a left.''' 

 For each of these sides aims at similarity with the other, and 

 so likewise do their several viscera ; and as the sides, though 

 dual, are knit together into unity, so also do the viscera tend to 

 be bilateral and yet one by unity of constitution. 



Those viscera which lie below the diaphragm exist one and all 

 on account of the blood-vessels \^ serving as a bond, by which 

 these vessels, while floating freely, are yet held in connection with 

 the body. For the vessels give off branches which run to the 

 body through the out-stretched structures,^ like so many anchor- 

 lines thrown out from a ship. The great vessel sends such 

 branches to the liver, the spleen, and the kidneys ; and these 

 viscera — the liver and spleen on either side and the kidneys 

 behind — attach the great vessel ^° immoveably to the body. The 

 aorta sends similar branches to the kidneys, but none to the liver 

 nor to the spleen.^^ 



These viscera, then, contribute in this manner to the compact- 

 ness of the animal body. The liver and spleen assist moreover 

 in the concoction of the food ; for both are rich in blood,^^ and 

 therefore of a hot character. The kidneys on the other hand 

 take part in the separation of the excretion which flows into 

 the bladder.^^ 



The heart then and the liver are essential constituents of every 

 animal ; the liver that it may effect concoction, the heart that 

 it may lodge the central source of heat. For some or other part 

 there must be which like a hearth shall hold the kindling fire ; 

 and this part must be well protected, seeing that it is, as it were, 

 the citadel of the body. 

 670 a. 



