206 TORREY 



TEXT-FIGURE 6. 



Optical sections of the successive stages in the formation of the alimentary 

 tract, oes.m, oes.r, oes.l, median, right, left oesophagoblasts ; gl, ectodermal gland ; 

 in, intestine ; st, stomach. Other letters as before. The ectomesoblast cells are 

 stippled lightly ; the ectodermal glands, heavily. 



