2 7 8 



INEZ WHIPPLE WILDER. 



in its development that oesophagus and stomach have already 

 completed their histogenesis, and the duodenum and rectum 

 practically so; leaving the yolk material in the remaining in- 

 testinal region. 



The lining of the oesophagus is thrown into longitudinal folds, 

 and is composed of columnar cells of the ciliated type with a 

 large number of active unicellular glands interspersed among 

 them (Fig. 8, b}. The stomach is sharply differentiated from the 

 cesophagus on the one hand and from the duodenum on the 



m 



m 



a 



FIG. 8. Cross sections of the oesophagus of (a) a 13 mm. embryo, and (b) a 

 newly hatched larva, shewing the change in the character cf the epithelial lining 

 which takes place during the few days previous to hatching, (a) m, mitosis; y, 

 last traces of yolk granules in the epithelial cells; (b) oil, ciliated epithelial cells; 

 me, mucous cells. Note the absence of folds in (a), and of mitosis in (b). Drawn 

 with Abbe camera. X 103. 



-other. It is divided into cardiac and pyloric regions, the former 

 expanded, piriform, and glandular, the latter tubular and far 

 more muscular. In both these regions of the stomach the 

 unicellular type of gland is lacking, but there are numerous 

 multicellular glands of the convoluted tubular type, opening 



