REPRODUCTION AND DEVELOPMENT 



269 



EGG HAVING ALMOST NO YO LK - AMPH IQXU S 



EGG CONTAINING A MODE RATE AM OU NT OF YOLK-AMPHIBIA 



EGG CONTAINING A LARGE AMOUNT OF YOLK - BIRDS 



Fig. 183. — The influence of yolk on gastrulation. (Modified, after Patten: Embry- 

 ology of the Chicly, published by P. Blakiston's Son and Company.) 



