GENERATION OF ANIMALS, II. vi. 



the physiologers " allege. This point is clear in the 

 case of birds, fishes, and insects : thus, some ** of 

 these are foniied out of an egg, after separation from 

 the mother, and it is in the egg that they get their 

 articulation ; and some animals *" do not breathe at 

 all, but are produced as larvae or as eggs ; others,** 

 which both breathe and get their articulation ^\■ithin 

 the uterus, do not however breathe until their lungs 

 have reached completion : with them, both the lungs 

 and the preceding parts become articulated before 

 they breathe. Further, the polydactylous quadru- 

 peds (such as the dog, the lion, the wolf, the fox 

 and the jackal) all bring forth their young blind, and 

 the eyelid does not separate until some -time after 

 birth. Hence it is clear that, with regard to all the 

 other parts as well, the same holds : just as the 

 characteristics of quaUty are there potentiality to 

 begin ^^ith and later on are formed in actuality, so 

 too those of quantity are formed — by the same causes 

 as those by which the characteristics of quality' are 

 differentiated, and two things are formed out of a 

 single one.^ As for pneuma, its presence is the result 

 of necessity, because liquid substance and hot sub- 

 stance are present, one being active and the other 

 being acted upon.^ 



Some of the early physiologers endeavoured to 

 describe the oi-der in which the various parts are 

 formed, but they were none too well acquainted with 

 what actually happens. As with everything else, so 



' e.g., two eyelids ; an example of a potential duality being 

 actualized. — See also App. B § 7, n. 



* i.fi., the pneuma is not iireiaoKTov, but avfjuj>vTov, derived 

 from within, and hence can serve as an " instrument " (see 

 789 b 3 ff. 1 charged with a specific *' movement " (see Introd. 

 g 68, and App, B, esp. § 32). 



2]1 



