EXTRA-EMBRYONIC MEMBRANES 



83 



allantoic cavity 



allantois 



somatopleure 



yolk-sac 

 / splanchno- 

 pleure ) 



sero-ammotic 

 cavity 



albumen 



vitelline 

 membrane 



belly stalk 



Fig. 30. — Schematic diagrams to show the extra-embryonic membranes 

 of the chick. {After Duval.) The diagrams represent longitudinal sections 

 through the entire egg. The body of the embryo, being oriented approximately 

 at right angles to the long-axis of the egg, is cut transversely. 



A, embryo of about two days incubation; B, embryo of about three days 

 incubation; C, embryo of about five days incubation; D, embryo of about fourteen 

 days incubation. 



