GENERx\TION OF ANIMALS, IV. i. 



as our premisses it may perhaps be clearer why and 

 by what cause one offspring becomes male and another 

 female. It is this. When the " principle " " is failing 

 to gain the mastery and is unable to effect concoction 

 OA\ing to deficiency of heat, and does not succeed in 

 reducing the material into its own proper form,^ but 

 instead is worsted in the attempt, then of necessity 

 the material must change over into its opposite con- 

 dition.'^ Now the opposite of the male is the female, 

 and it is opposite in respect of that whereby one is 

 male and the other female.** And since it differs in 

 the abiUty it possesses, so also it differs in the instru- 

 ment which it possesses. Hence this is the con- 

 dition * into which the material changes over. And 

 when one \'ital part changes,^ the whole make-up of 

 the animal differs greatly in appearance and form. 

 This may be observed in the case of eunuchs ; the 

 mutilation of just one part of them results in such a 

 great alteration of their old semblance, and in close 

 approximation to the appearance of the female. The 

 reason for this is that some of the body's parts' are 

 " principles," and once a principle has been " moved " 

 [i.e., changed), many of the parts which cohere ^ with 

 it must of necessity change as well. 



Let us assume then (1) that " the male "is a The 

 principle and is causal in its nature ; (2) that a male ^u^'^^f 

 s male in \irtue of a particular abiUty, and a female "ex u the 

 female in virtue of a particular inabiUty ; (3) that the ** 

 ine of determination between the ability and the 

 nability is whether a thing effects or does not effect 



hat the sexual parts, as distinct from the sexes, are " prin- 

 •iples " ; but his position is made clear by the passage 

 66 b 2 flF. 



" Are of a piece with it " : cf. 764 b 24, 25. 



391 



