GENERATION OF ANIMALS, IV. vi. 



increase of size is secreted to yield seminal residue — 

 since, for a solid-hoofed animal, the pig is not large 

 in size ; at the same time and more commonly, it is 

 cloven-hoofed, as though it were at odds with the 

 nature of the solid-hoofed animals. On account of 

 this, then, it not only produces sometimes one off- 

 spring, and two, but also and for the most part it 

 produces numerous offspring, and it brings their 

 nourishing to completion because of its fine physical 

 condition : it is like a rich soil which can provide 

 plants with sufficient and indeed abundant nourish- 

 ment. 



The offspring of some of the birds also are hatched 

 in an imperfect state, and blind " ; viz. , of those which 

 lay numerous eggs although they themselves are 

 small in physique — e.g., the crow, the jay,* sparrows, 

 and swallows '^ ; and of those birds which lay few 

 eggs and yet do not provide in the egg abundant 

 nourishment'* for the chick — e.g., the ring-dove, the 

 turtle-dove, and the pigeon. And on this account, 

 if the eyes of a swallow are deliberately put out while 

 the bird is still young, they recover, because the 

 injury is inflicted during the process of their forma- 

 tion and not after its completion ; that is why they 

 grow and spring up afresh.* In general, then, the 

 reason why offspring are born early before their 

 formation is perfected, is because of inability to bring 

 their nourishing to completion ; and the reason why 

 they are born in an imperfect state is because they 



viz., the young skin. This may happen many times in 

 succession if the experiment is repeated. The connexion 

 between regeneration and embryonic growth is well grasped 

 by Aristotle, but there are of course some animals, such as 

 the newts, where the power of regeneration is retained 

 throughout adult life (c/. H.A. 508 b 4> if.). 



457 



