GENERATION OF ANIMALS, IV. viii. 



this residual secretion but at the same time prevents 

 it from making its way out,, the whole of the residue 

 is bound to collect in the empty spaces which are 

 situated on the same passages.'* In each kind of 

 animal the place around the breasts is just such an 

 empty space, and it is so for both of the two possible 

 reasons : it was formed such as it is (a) for the sake 

 of the best, and (6) by necessity. And it is precisely 

 here that the concocted nourishment for the young 

 animals takes shape and is formed. As for its con- 

 coction : to explain that, either the reason stated * 

 may be taken, or the opposite one, since it is just as 

 reasonable to adopt the view that as the embryo is 

 bigger it takes more nourishment, so that there is 

 less nourishment left over at this particular time ; 

 and a smaller amount takes less time to concoct. 



It is clear that milk is possessed of the same nature 

 as the secretion out of which each animal is formed 

 (this has in fact been stated already) '^ : the material 

 which supplies nourishment and the material out of 

 which Nature forms and fashions the animal are one 

 and the same.** And this material, in the case of 

 blooded animals, is the bloodlike liquid, since milk is 

 concocted, not decojnposed , blood. As for Empedocles, 

 either he was mistaken, or else his metaphor was a 

 bad one, when he wrote * how the milk is formed 



On the eighth moon's tenth day, a whitish pus. 



No ; putrefaction and concoction are opposites, and 

 pus is a putrefaction, whereas milk is to be classed 

 as something concocted. In the natural course of 



* i.e., that the embryo requires less nourishment. 



' At T39 b 26. " Cf. 744 b 35. 



• Diels, Vortokr.^ 31 B 68. 



473 



