456 ON GENERATION. 



that the superior part of the vitellus, or the hemisphere which 

 regards the ovary, is almost free from any contact or cohesion 

 with the peduncle, in the superior part of the cup or hollow of 

 which nevertheless, but somewhat to the side, the spot or cica- 

 tricula in question is placed. The peduncles becoming detached 

 from the vitelli can therefore in no way be said to leave 

 any trace of their attachments behind them. Of the great 

 importance of this spot in generation I have already spoken 

 in the historical portion of my work. 



But I have still, always following my old teacher Fabricius 

 as my guide on the way, to treat of the uses of the cavity in the 

 blunt end of the egg. 



Fabricius enumerates various conveniences arising from this 

 cavity, according to its dimensions. I shall be brief on the 

 subject : it contains air, and is therefore useful in the ventila- 

 tion of the egg, assisting the perspiration, refrigeration, and 

 respiration, and finally the chirping of the chick. Whence this 

 cavity, small at first, is larger by and by, and at last becomes 

 of great size, as the several offices mentioned come into play. 



Thus far have we spoken of the generation of the egg and 

 chick, and of the uses of the several parts of the egg ; and to 

 the type exhibited we have referred the mode of generation of 

 oviparous animals in general. We have still to speak of the 

 generation of viviparous animals, in doing which we shall as 

 before refer all to a single familiarly known species. 



EXERCISE THE SIXTY-SECOND. 



An egg is the common origin of all animals. 



" Animals," says Aristotle, 1 " have this in common with 

 vegetables, that some of them arise from seed, others arise spon- 

 taneously; for as plants either proceed from the seed of other 

 plants, or spring up spontaneously, having met with some pri- 

 mary condition fit for their evolution, some of them deriving 

 their nourishment from the ground, others arising from and 

 living on other plants ; so are some animals engendered from 

 cognate forms, and others arise spontaneously, no kind of cognate 



1 Hist. Anim. lib. 5, cap. 1. 



