GENERATION OF ANIiMALS, I. xxi. 



we said happened with those insects where the 

 female inserts a part into the male). Here is the 

 evidence. Supposing a hen bird is in process of pro- 

 ducing wind-eggs, and then that she is trodden by the 

 cock while the egg is still completely yellow and has 

 not yet started to whiten : the result is that the eggs 

 are not wind-eggs but fertile ones. And supposing 

 the hen has been trodden by another cock while the 

 egg is still yellow," then the whole brood of chickens 

 w^hen hatched out takes after the second cock. Some 

 breeders who speciaUze in first-class strains act upon 

 this, and change the cock for the second treading. 

 The implication is (a) that the semen is not situated 

 inside the egg and mixed up with it, and (b) that it 

 is not dra\vn from the whole of the body of the male : 

 if it were in this case, it would be draw'n from both 

 males, so the offspring would have every part twice 

 over. No ; the semen of the jnale acts otherwise ; 

 in virtue of the dynamis which it contains it causes the 

 material and nourishment in the female to take on a 

 particular character ; and this can be done by that 

 semen which is introduced at a later stage, working 

 through heating and concoction, since the egg takes 

 in nourishment so lono^ as it is <jrowinff. 



The same thing occurs in the generation of ovi- 

 parous fishes. When the female fish has laid her 

 eggs, the male sprinkles his milt over them ; the eggs 

 which it touches become fertile, but the others are 

 infertile, which seems to imply that the contribution 

 which the male makes to the young has to do not 

 with bulk but with specific character. 



What has been said makes it clear that, in the case 

 of animals which emit semen, the semen is not drawn 

 from the whole of the body, and also that in genera- 

 lly 



