ANIMALS. 371 



out the cock, very small. It was foiind< by the 

 microscope, to be a kind of bag, containing a trans- 

 parent liquor, in the midst of which the embryo 

 was seen to reside. The embryo resembled a 

 composition of little threads, which the warmth 

 of future incubation tended to enlarge, by vary- 

 ing, and liquefying the other fluids contained 

 within the shell, and thus pressing them either 

 into the pores or tubes of their substance. 



Upon placing the eggs in their proper warmth,* 

 either under the sun, or in a stove, after six hours 

 the vital speck begins to dilate like the pupil of 

 the eye. The head of the chicken is distinctly 

 seen, with the back-bone, something resembling 

 a tadpole, floating in its ambient fluid, but as yet 

 seeming to assume none of the functions of ani- 

 mal life. In about six hours more, the little ani- 

 mal is seen more distinctly; the head becomes 

 more plainly visible, and the vertebrae of the 

 back more easily perceivable. All these signs of 

 preparation for life are increased in six hours 

 more ; and at the end of twenty-four hours, the 

 ribs begin to take their places, the neck begins 

 to lengthen, and the head to turn to one side. 



At this time,* also, the fluids in the egg seem 

 to have changed place : the yolk, which was be- 

 fore in the centre of the shell, approaches nearer 

 to the broad end. The watery part of the white 

 is, in some measure, evaporated through the 

 shell, and the grosser part sinks to the small end. 

 The little animal appears to turn towards the 



* Malpighi. * Harvey. 



