GENERATION OF ANIMALS, IV. i. 



been amply observed by us from dissections in all the 

 \'ivipara, both in the land-animals and in the fishes. 

 Now if Empedocles had not detected this, it is under- 

 standable that he should have made the mistake of 

 assigning the cause he did ; if on the other hand he 

 had detected it, it is extraordinary' that he should still 

 continue to think that the cause is the heat and cold 

 of the uterus, since according to his theorv the twins 

 should both turn out male, or both female ; whereas 

 in actual fact we do not observe this to occur. 



Also, he says that the parts of the creature which 

 gets formed are " torn asunder " " ; some, he savs, are 

 in the male and some in the female, and that also 

 explains why they desire intercourse with each other. 

 If so, necessity requires that the physical substance ^ 

 of these parts '' as well as of the others is " torn 

 asunder " and that a junction takes place, not that 

 the difference is due to coohng or heating. However, 

 discussion of a cause of this sort might well prove 

 lengthy, as the whole cast of this cause seems to be 

 a product of the imagination. If on the other hand 

 the truth about semen is as we have actually stated — 

 i.e., that it is not drawn from the whole body and 

 that the secretion from the male provides no material 

 at all for the creatures which get formed^ — then we 

 must take up our stand against Empedocles and 

 against Democritus and against anyone else who 

 maintains this position, because (a) it is impossible 



below. fieyeBos thus means something which has size, i.e., 

 a physical body or substance. Empedocles, says Aristotle, is 

 inconsistent in saying (a) that the physical substance of the 

 parts is present as such in the parents to begin with, and 

 (6) that the formation of the sexual parts is due to the action 

 of heat and cold. 



" Viz., testes and uterus. 



377 



