114 



THE THIRD DAY. 

 Fig. 37. 



[chap 



MB 



Chick op the Third Day (Fifty-four Hours) viewed from 

 underneath as a transparent object. 



a', the outer amniotic fold or false amnion. This is very con- 

 spicuous around the head, but may also be seen at the tail. 



a. the true amnion, very closely enveloping the head, and here 

 seen only between the projections of the several cerebral 

 vesicles. It may also be traced at the tail. 



In the embryo of which this is a drawing, the head-fold of the 

 amnion reached a little farther backward than the reference u, 



