454 EMBRYOLOGY OF THE CHICK 



forming this entodermal portion takes no further part in the peripheral 

 expansion, though this entodermal part grows back toward the center 

 of the blastoderm, leaving the blastopore region behind. The marginal 

 region continues to grow and soon encloses it, so that by the time the 

 blastopore conies to close, it lies within the recompleted circle of the 

 germ wall (Fig. 259, C). 



