PARTS OF ANIMALS, III. xii.-xiii. 



found first of all even among the viviparous blooded 

 animals ; but it is more noticeable among the fishes 

 and oviparous quadrupeds, whose livers differ not 

 only from those of the Vivipara, but also from each 

 other's. In birds, the liver very closely resembles 

 that of the Vivipara : in both, its colour is pure and 

 blood-like. The reason for Avhich is, that their bodies 

 give a very free passage to the breath, which means 

 that they retain very httle foul residue ; hence, indeed, 

 some of the Vivipara have no gall-bladder, and this is 

 largely due to the very considerable assistance given 

 by the liver in maintaining a good blend" and healthi- 

 ness in the body. This is because the purpose which 

 these viscera serve lies chiefly in the blood, and after 

 the heart the liver contains more blood than any 

 other of the viscera. In most of the oviparous 

 quadrupeds and the fishes the liver is yellowish, and 

 in some of them it is altogether bad-looking, on a 

 par Avith the bad blend of the rest of their bodies. 

 This happens in the toad, the tortoise, and the like. 



As for the spleen : In horned animals that have 

 cloven hoofs it is rounded : e.g. in the goat, the sheep, 

 and similar animals ; unless greatness of size has 

 made it groΛv out at some point lengthways, as in the 

 case of the ox. In all the polydactylous animab the 

 spleen is long, as in the pig, in man, and in the dog. 

 In animals with solid hoofs the spleen is intermediate 

 between the two and has the characteristics of both : 

 in one place it is broad, in another narrow, as exempli- 

 fied in the horse, the mule, and the ass. 



XIII. Now the viscera differ from the flesh not only 

 in the bulkiness of their mass, but also in their 

 situation, for the flesh is on the outside of the body, 

 while they are inside. The reason for this is that 



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