* MODIFICATION OF REPRODUCTIVE PROCESS 75 



provides it with an ample supply of food, so that it does 

 not have to get into the outer world and fend for itself 

 until a very late stage in its development. Thus a watery 

 environment is no longer necessary for the early fish-like 



FIG. 44. 



Diagram illustrating the contents of a Hen's egg which has been incubated for 

 twelve days. The young bird is seen within the cavity of the amnion. Attached 

 to its lower side are seen two stalks the hinder one connected with the allantois 

 (all) which lines the shell, the other with the yolk-sac in which the yolk (y) is con- 

 tained, alb, remains of albumen or white. (From Graham Kerr's Embryology, 

 after a figure by Lillie in his Development of the Chick.) 



stages, for these are passed through in the interior of the 

 egg-shell. 



Then the body of the young bird comes to be enclosed 

 in a thin bag filled with watery fluid, and known as the 

 Amnion (see Fig. 44), which forms a water- jacket to pro- 

 tect its delicate substance from the jars to which its being 

 on land exposes it. 



Again, a bladder-like organ the Allantois (Figs. 44 

 and 45, all) bulges out from its body and flattens itself 



