GENERATION OF ANIMALS, II. v.-vi. 



steps towards the starting-point whence she set out. 

 The process of formation, genesis, starts from not- 

 being and advances till it reaches being ; that of 

 decay starts from being and goes back again till it 

 reaches not-being. 



After the " principle " is formed, the other parts VI 

 are formed, the internal ones earUer than the exter- n|^^*(^f^{,h^ 

 nal, as I have said." The larger parts become visible, embryo 

 however, earlier than the smaller ones, although some ' '""^ ^ 

 of them are not in fact formed earlier. First the 

 parts above the diaphragm become articulated, and 

 these are larger in size, whereas that which is below 

 is smaller and less clearly defined.** This happens in 

 all cases where the upper and the lower portions " 

 are definite and distinct, except Insects : in those 

 Insects which are produced as larvae, the increase 

 occurs towards the upper part, as this is smaller to 

 begin with. The only locomotive animals in which 

 there is no definite distinction between the upper 

 and lower portions are the Cephalopods.*^ What has 

 been said here applies to plants as well : the forma- 

 tion of the upper portion precedes that of the lower : 

 seeds send out their roots before their shoots.* 



Now the parts of animals are differentiated by 

 means of pneuma f ; but this is not the pneuma of the 

 mother, nor that of the creature itself, as some of 



he says (705 b 6), in plants, the roots are the " upper " 

 portion, since it is through their roots that plants get their 

 nourishment, just as animals do through the mouth. Cf. 

 the end of the present paragraph, 741 b 34 flF . ; also the 

 passage in P. A. 686 b 21 ff. 



■* Because (720 b 18, P. A. 684 b 15, 685 a 1) their back- 

 part is drawn up on to the front-part, their tail-end is bent 

 right over to meet the front, and in consequence the residual 

 vent is brought close to the mouth. 



• See note on 741 b 30. ' See App. B §§ 7 ff. 



209 



