GENERATION OF ANIMALS, I. xviii. 



able to be formed into either male or female <* (imply- 

 ing that the sexual part is not present in the semen), 

 it is clear that it is not the semen's being drawn from 

 some one part which causes the offspring to be female, 

 nor, in consequence, is it responsible for the special 

 physical part which is peculiar to the two sexes. 

 And what can be asserted about the sexual part 

 can equally well be asserted about the other parts ; 

 since if no semen comes even from the uterus, the 

 same will surely hold good of the other parts as well. 



Further, some animals are formed neither from 

 creatures of the same kind as themselves nor from 

 creatures of a different kind ; . examples are : flies 

 and the various kinds of fleas as they are called. 

 Animals are formed from these, it is true, but in these 

 cases they are not similar in character to their 

 parents ; instead we get a class of larvae. Thus in 

 these creatures which differ in kind from their parents 

 we clearly have animals which are not formed out of 

 semen dra>\"n from every part of the body, for if 

 resemblance is held to be a sure sign that this has 

 occurred, then they would resemble their parents. 



Further, even among the animals there are some 

 which generate numerous offspring from one act of 

 coition, a phenomenon which is, indeed, universal 

 with plants ; these, as is manifest, produce a whole 

 season's fruit as the result of one single movement.'' 

 Now how is this possible on the supposition that the 

 semen is secreted from the whole body ? One act of 

 coition, and one effort of segregation, ought neces- 

 sarily to give rise to one secretion and no more. That 

 it should get divided up in the uterus is impossible, 



combined in the " fetation " of an animal. See also 728 a 27, 

 731 a 1. 



67 



