38 



Mary Blount. 



Fig. 18. — Surface view of a pigeon's egg taken from the oviduct at 11.35 

 p. m., 7 hours and 40 minutes after the bird had laid another egg. The longer 

 cleavage plane is parallel to the axis of the future embryo. There was no 

 accessory cleavage, but the periblast and blastodisc were differentiated. 



Fig. 19. — Surface view of a pigeon egg taken from the oviduct at 1.00 a. m., 

 about 5 hours after fertilization. Notice the blastodisc and periblast, and 

 the excentric position of the cleavage. 



