LECTURE I. 15 



ing of the properties of life, he says " it is 

 something that prevents the chemical de- 

 composition, to which dead animal and 

 vegetable matter is so prone ; that regulates 

 the temperature of the bodies it inhabits, 

 and is the cause of the actions we observe 

 in them." All these circumstances, though 

 deduced from an extensive contemplation 

 of the subject, may, however, be legiti- 

 mately drawn from observations made on 

 the egg. A living egg does not putrify 

 under circumstances that would rapidly 

 cause that change in a dead one. The 

 former resists a degree of cold that would 

 freeze the latter. And when subjected to 

 the genial warmth of incubation, the 

 matter of it begins to move or to be moved 

 so as to build up the curious structure of 

 the young animal. 



The formation of the embryon in galli- 

 naceous ova was particularly attended to 

 by Mr. Hunter ; and he was of opinion, 

 that motions began in various places in the 

 cicatricula so as simultaneously to form 

 parts of the embryon and its appendages. 



