GENERATION OF ANIMALS, I. x-^aii. 



supplies growth, as the result of decomposition pro- 

 ceeding contrary to nature. Now it is clear that 

 semen cannot possibly be (1) one of the parts ; since 

 although it is uniform," it does not serve as the 

 material out of which any other parts ^ are composed, 

 as sinew and flesh do ; nor again is it separate and 

 distinct,^ whereas all the other parts are. Nor (2) is 

 it something contrary to nature, or a deformation,'' 

 (a) because it is present in every single individual, and 

 (6) because the natural organism develops out of it. 

 As for (5) nourishment, obviously this is introduced 

 into the body from without. It must therefore be 

 either (4) a colliquescence or (3) a residue. The 

 early thinkers appear to have supposed it was a 

 colliquescence, because to say that it is drawn from 

 the whole body in virtue of the heat which the move- 

 ment produces,* is equivalent to saying that the 

 semen is a colliquescence. But colUquescence be- 

 longs to the class of things that are contrary to nature, 

 and from such things nothing that is in accordance 

 with nature is ever formed. Therefore the semen 

 must of necessity be a residue. ^ ery well. Every 

 residue results either from useful or from useless 

 nourishment. By " useless nourishment " I mean 

 that which contributes nothing further to the natural 

 organism and which if too much of it is consumed 

 causes very great injury to the organism ; " useful 

 nourishment " is the opposite of this. It is obvious 

 that semen cannot be a residue resulting from useless 

 nourishment, for while residue of that sort is found in 



epxerat airo navros tou vypov tov ev t<x> adifiaTt, eovros to loxv- 

 poTOTov dnoKpiddv tovtov 8e Icrropiov robe, ori aTO/cpiVerai to 

 icrxvporaTOV, ort frrqv Xayvevacofiev afUKpov ovrco fifdevm, 

 dadevees yivofieda witli Aristotle's own statement at 125 b 6-8. 



79 



