GENERATION OF ANIMALS, I. xvi.-xvii. 



them by the eg'gs at the time of breeding. In the 

 females the part that answers to the uterus is divided 

 and extends alongside the gut, as in other animals ; 

 this is where the fetations are formed. This can be 

 clearly seen in locusts and in any insect whose nature 

 it is to copulate, provided it is large enough ; most 

 insects however are too small." 



Such is the manner of animals' instrumental parts 

 connected vvith generation, which I had not dealt 

 with in my previous treatise. ** Of the " uniform " '^ 

 parts, semen and milk were there left undescribed, 

 and the time has now come to speak of these. We 

 v\ill deal with semen without delay, and with milk 

 in the chapters which are to follow.*^ 



Some animals discharge semen plainly, for instance XVII 

 those which are by nature blooded animals ; but it '^^'"''"■ 

 is not clear in which way Insects and Cephalopods 

 do so. Here then is a point we must consider : Do 

 all male animals discharge semen, or not all of them ? 

 and if not all, why is it that some do and some do 

 not ? and further. Do females contribute any semen, 

 or not ? and if they contribute no semen, is there no 

 other substance at all which they contribute, or is 

 there something else which is not semen ? And 

 there is a further question which we must consider : 

 What is it which those animals that discharge semen 

 contribute towards generation by means of it ? and 

 generally, what is the nature of semen, and (in the 

 case of those animals which discharge this fluid) what 

 is the nature of the menstrual discharge .^ 



It is generally held that all things are formed and Theor>. 



reason is that, according to him, they do not copulate : see 

 731 b 8 ff. » D« partibus. 



' See Introd. § 19. <* Book IV, ch. 8. 



4d 



