GENERATION OF ANIMALS, II. ni. 



contains all the parts of the body potentially, though 

 none 171 actuality ; and " all " includes those parts 

 which distinguish the two sexes. Just as it some- 

 times happens that deformed " offspring are produced 

 by deformed parents, and sometimes not, so the off- 

 spring produced by a female are sometimes female, 

 sometimes not, but male. The reason is that the 

 female is as it were a deformed male ; and the 

 menstrual discharge is semen, though in an impure 

 condition ; i.e., it lacks one constituent, and one only, 

 the principle of Soul.* This explains why, in the 

 case of the wind-eggs produced by some anknals, the 

 Ggg which takes shape contains the parts of both 

 sexes, '^ but it has not this principle, and therefore it 

 does not become a Uving thing with Soul in it ; this 

 principle has to be supplied by the semen of the 

 male, and it is when the female's residue secures this 

 principle that a fetation is formed.'' 



^ [WTien substances which are fluid but also cor- 

 poreal are heated, an outer layer forms round them, 

 just as we find a solid layer forming round things that 

 have been boiled, as they cool. All bodies depend on 

 something glutinous to hold them together ; and as 

 their development proceeds and they become larger, 

 this glutinous character is acquired by the substance 

 known as sinew, which holds the parts of animals 

 together (in some it is actual sinew which does 

 this, in others its counterpart).-'^ Skin, blood-vessels, 

 membrane and all that class of substances are of the 



** Or, " it becomes a fetation," i.e., a perfect fetation ; see 

 7.S7 a 10. 



* The following paragraph, which consists partly of re- 

 marks taken from elsewhere, is irrelevant here. 



' Sometimes, as here, " counterpart " could be repre- 

 sented by the modern term " analogue " ; cf. P. A. 653 b 36. 



175 



