GENERATION OF ANIMALS, I. viii. 



occur. To begin with, not all the Vivipara have the 

 same arrangement. All that are land-animals, in- 

 cluding human beings, have the uterus placed low 

 down by the pudenda, whereas the v'iviparous 

 Selachia " have it higher up by the diaphragm. x\nd 

 then again, the Ovipara show the same variations. 

 Fishes have the uterus low down Uke human beings 

 and the vi\iparous quadrupeds, whereas birds have 

 it higher up, and so do the oWparous quadrupeds. 

 Nevertheless, there is rhyme and reason even in these 

 contradictory phenomena. First of all, the egg- 

 laying animals have different ways of laying their 

 eggs, (a) Some creatures' eggs are imperfect when 

 laid — e.g.. those of fishes, which become perfected. 

 i.e., grow, outside the creature which produces them.^ 

 The reason is that these animals are very prolific and 

 this is their function," as it is that of plants ; so that 

 if they brought the eggs to a state of perfection 

 inside their bodies, the eggs would of necessity be 

 few in number, whereas in actual fact they produce 

 so many that each uterus seems to be just one mass 

 of ^gg, at any rate in the very small fishes, which are 

 the most prolific of all. The same is true both of 

 those plants and of those animals which are of a 

 corresponding nature ** in their own classes ; what 



carbohydrates, etc.) to make each an embryo, are insuffi- 

 ciently supplied with water and inorganic materials ; these 

 they have to absorb from their environment. Hence their 

 swelling. Though the main bulk of this is due to water- 

 intake, it is interesting that the greater part of the copper, 

 for example, which i.b present in the respiratory blood- 

 pigment of the octopus at the time of hatching is derived, 

 not from the egg as laid, but from the surrounding sea-water. 

 See also 732 b 5, etc 



' Cf. 717 ei22. " ».*., small. 



29 



