170 ON GENERATION. 



duced from ova. Passing by almost all insects and the whole 

 of the less perfect animals, which are obviously produced from 

 eggs, the greater number of the more perfect are also engen- 

 dered from eggs." And then he goes on to particularize : " All 

 feathered creatures ; fishes likewise, with the single exception of 

 the whale tribes ; Crustacea, testacea, and all mollusca ; among 

 land animals, reptiles, millepeds, and all creeping things ; and 

 among quadrupeds, the entire tribe of lizards." 



We, however, maintain (and shall take care to show that it 

 is so), that all animals whatsoever, even the viviparous, and man 

 himself not excepted, are produced from ova; that the first con- 

 ception, from which the fostus proceeds in all, is an ovum of 

 one description or another, as well as the seeds of all kinds of 

 plants. Empedocles, 1 therefore, spoke not improperly of the 

 oviparum genus arbor eum, " the egg-bearing race of trees." The 

 history of the egg is therefore of the widest scope, inasmuch 

 as it illustrates generation of every description. 



We shall, therefore, begin by showing where, whence, and 

 how eggs are produced ; and then inquire by what means and 

 order and successive steps the foetus or chick is formed and per- 

 fected in and from the egg. 



Fabricius has these additional words : " The foetus of animals 

 is engendered in one case from an ovum, in another from the 

 seminal fluid, in a third from putrefaction ; whence some crea- 

 tures are oviparous, others viviparous, and yet others, born of 

 putrefaction or by the spontaneous act of nature, automatically." 



Such a division as this, however, does not satisfy me, inas- 

 much as all animals whatsoever may be said in a certain sense 

 to spring from ova, and in another certain sense from seminal 

 fluid; and they are entitled oviparous, viviparous, or vermi- 

 parous, rather in respect of their mode of bringing forth than of 

 their first formation. Even the creatures that arise spontane- 

 ously are called automatic, not because they spring from putre- 

 faction, but because they have their origin from accident, the 

 spontaneous act of nature, and are equivocally engendered, as it 

 is said, proceeding from parents unlike themselves. And, then, 

 certain other animals bring forth an egg or a worm as their 

 conception and semen, from which, after it has been exposed 



1 Arist. De Gen. Anim. lib. i, cap. 20. 



