THE INCUBATION OF THE EGG 



173 



path around the large end of the egg, at the saipe time 

 cutting the membranes within. When the shell is nearly 



FiQ. 85 



Appearance of a chick embryo after forty-eight hours in an incubator 

 (Courtesy of Kansas Experiment Station.) 



FiQ. 86 



Appearance of a chick embryo after sixty hours in an incubator. 

 (Courtesy of Kansas Experiment Station.) 



cut around a final convulsion by the chick finishes the break, 

 and the chick can emerge from the egg. 



