PLATE 3 



EXPLANATION OF FIGURES 



11 Section of a young pharynx showing beginning of differentiation of gland- 

 cells, G.C., and a transition cell differentiated, T.C. Br, 'brain;' E, enteric 

 epithelium. X 1400. 



12 Section of an older pharynx than one shown in 11. Two transitional 

 cells shown, T.C. Many gland-cells present, G.C. Br, 'brain;' E, enteric 

 epithelium. X 1400. 



322 



