EXTRA-EMBRYONIC MEMBRANES 



allantoic cavity 



allantois 



extra-embryonic 

 coelom 



somatopleure 



yolk-sac 

 ( splanchno- 

 pleure ) 



albumen 



vitelline 

 membrane 



allantoic cavity 

 allantois 



shell 



amniotic 

 cavity 



sero-amniotic 

 cavity 



yolk-sac 



yolk 



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. 



