200 FRANKLIN PARADISE JOHNSON 



of internal })i-essure by their l)ull)ous appearance and by the 

 flattening of the lining epithelium of the more superficially lying 

 part of the cyst (fig. 11). In many respects these cysts are 

 similar to those found in the \'ermiform ]:)rocess (compare fig. 

 11 with hgs. 9 and 10) but differ from them by their more super- 

 ficial position and in that they can rarely be considered to be 

 entirely separated from the surface epithelium. Moreover, they 

 have a different fate from those of the vermiform process. In- 

 stead of the epithelium entirely degenerating, the cyst collaps- 

 ing, and finally being absorbed, the cysts of the rectum open up 

 with the intestinal lumen and become glands again, at, least 

 this interpretation seems justifiable, since the cysts gradually 

 disappear without showing such degenerative processes as are 

 easily recognizable in those of the vermiform process. 



The condition found in the transverse colon of an embryo 

 of 70 mm. is not much in advance of the same portion of the 

 large intestine at 65 mm. Its epithelial tube has a diameter 

 of 0.54 mm. The lumen is relatively large and the villi project 

 into it 0.09 to 0.13 mm. The cells forming the epithelium are 

 tall columnar, 0.025 in height, and contain at their basal ends, 

 elongated nuclei. The protoplasm, which stains decidedly A^el- 

 low with orange-G, appears to be mucous in character. Here 

 and there swollen goblet cells are seen. A small portion of the 

 sigmoid colon presents an appearance similar to that described 

 in the rectum at 65 mm. It measures 0.54 mm. by 0.72 mm., 

 and contains folds and villi 0.23 to 0.27 mm. in height. Epi- 

 thelial glands and cysts are found in large numbers. In the 

 rectinn the same conditions are presented, although the epi- 

 thelial tube is larger and the villi taller (0.25 to 0.32 mm.). The 

 latter seem, however, to be so fused together that they appear 

 in many places as irregular running folds. Goblet cells are 

 everywhere numerous. 



In a well preserved transverse colon of an embiyo of 73 mm. 

 the epithelial tube measures 0.58 mm. in diameter. The villi 

 and folds, some of which are now 0.22 to 0.23 mm. high, decrease 

 to a marked extent the size of the lumen. In width the villi 

 show a slight increase, being 0.09 to 0.18 nmi. through at their 



