GENERATION OF ANIMALS, I. xviii. 



similar phenomenon is that of grape-vines which 

 " go goaty," rampaging all over the place because 

 they are getting too much nourishment. (The reason 

 for the phrase " go goaty " is that they behave just 

 like he-goats, which when they get fat indulge less 

 in copulation, and incidentally this explains why goats 

 are made to slim before the breeding season comes 

 on.) And further it seems that fat people, men and 

 women alike, are less fertile than those who are not 

 fat, the reason being that when the body is too well 

 fed, the effect of concoction upon the residue is to 

 turn it into fat (since fat also is one of the residues, 

 a healthy one, because it results from good living). 



Some living things actually produce no semen at 

 all : examples are the willow and the poplar. Both 

 reasons together are responsible for this state of 

 affairs ; in other words, on account of their weakness 

 the trees cannot concoct their nourishment, and on 

 account of their strength they use it all up, as 

 described above. Similarly, some animals are pro- 

 lific, and have abundance of semen because they are 

 strong, but others because they are weak ; the ex- 

 planation being that in the latter case much useless 

 residue gets mixed up with the semen, and in some 

 instances, when there is no clear way open by which 

 the evacuated matter may leave, it actually produces 

 disease, from which some recover though others 

 succumb. Their semen is contaminated by the col- 

 liquescences which get into it, just as they do into 

 the urine — another malady by no means unknown. 



" [Further, the same passage serves both for the 

 residue and for the semen : (a) in those animals which 



b 29 ff.) ; the latter part refers to the subjects discussed in 

 725 a— 726 a. 



87 



