EMBRYOLOGY OF THALASSEMA MELLITA 



207 



quartets of the anterior and lateral quadrants. Before the 

 posterior portion of the blastopore has closed three cells 

 (2<3^2. 2. 1. 2. 1 +> 2(^2. 2. 1. 2. 3^2. 1. 1) becoHie prominent because of their 

 greater size (PL II, Fig. 24). These cells have already been 



(oes.m) 1^ 



,.rc 



(oes.r) 



Fig. 6. 



designated as oesophagoblasts. The anterior one attains a very 

 great size (Text-Fig. 6, A) and at the end of gastrulation is the 

 only cell that separates the anterior end of the blastopore from 

 the prototroch (PI. II, Fig. 24). By the continued insinking of 



