PARTS OF ANIMALS, IV. x. 



Generation.'^ Still, it is clear that the actual forms of 

 these parts is determined of necessity by the function 

 they have to perform. The male organ, however, 

 exhibits differences corresponding to those of the 

 body as a whole, for some animals are more sinewy, 

 some less. Further, this organ is the only one which 

 increases and subsides apart from any change due 

 to disease. Its increasing in size is useful for copula- 

 tion, its contraction for the employment of the rest 

 of the body, since it would be a nuisance to the 

 other parts if it were always extended. And so it 

 is composed of substances which make both con- 

 ditions possible : it contains both sinew and cartilage ; 

 and so it can contract and expand and admits air 

 into itself. All female quadrupeds discharge the 

 urine backwards, as this arrangement is useful to 

 them for copulation. A few males do this (among 

 them are the lynx, the lion, the camel, and the 

 hare), but no solid-hoofed animal does so. 



The rear parts and the parts around the legs are Rear parta. 

 peculiar in man compared with the quadrupeds, nearly 

 all of which (Ovipara as well as Vivipara) have a tail, 

 which even if it is not of any great size, still is present 

 for a token as a sort of stump. Man has no tail, but 

 he has buttocks, which no quadruped possesses.^ In 

 man, the legs, both in thighs and calves, are fleshy : 

 in all other animals that have them (not only Vivi- 

 para) the legs are fleshless, being sinewy, bony and 

 spinous. One might say that there is a single ex- 

 planation which covers them all, which is, that man is 



« At 716 a 2—721 a 29. 



'' There seems to be something wrong with this statement, 

 but perhaps when taken in conjunction with the whole of the 

 argument which follows, it may appear less unjustifiable. 



ofiiKpov vulg. * KVT^fias] TTobas Y. 



385 



