The Early Development of the Pigeon's Egg. 



15 





Fig. 9. — Longitudinal section of pigeon's egg at the time of disappear- 

 ance of tlie sperm nuclei; on the left (anterior), the marginal cell has 

 become open, *. c, continuous with the marginal periblast. On the right the 

 marginal cell is slightly separated from the periblast at the surface. Surface 

 view of the egg showed traces of accessory cleavage ; note continuity of the 

 central cells with central periblast. 1. Marginal cells. 2. Cone of proto- 

 plasm. 3. Marginal periblast. 4. Neck of latebra (white yolk). 5. Yellow 

 yolk. Egg tak€Mi 7 a. m.. about 11 hours after fertilization (estimated). 



