202 FRANKLIN PARADISE JOHNSON 



which seem to be closely crowded together, and stain inten- 

 sively. These groups of cells form small knob-like projections 

 and are the beginnings of the intestinal glands. 



In the ascending, descending, and sigmoid colons, as seen 

 from transverse and longitudinal sections, both villi and the 

 beginnings of glands are distinguishable. The villi gradually 

 increase in length as the large intestine is followed caudally; 

 thus in the ascending colon they are about 0.14 to 0,16 mm. in 

 height; in the transverse, 0.18 to 0.20 mm.; in the descending 

 colon, 0.22 to 0.25 mm.; in the sigmoid, 0.27 to 0.32 mm.; while 

 in the rectum, 0.27 to 0.36 mm. In many places their apices 

 are in close contact with each other, appearing as though fused. 

 Likewise, the glands show a more advanced stage of growth as 

 the large intestine is followed downward. In the ascending 

 colon they are scarcely visible; in the rectum they are very dis- 

 tinct. Except for this more advanced stage of development, 

 conditions in the rectum are not so strikingly different from 

 those in the remainder of the colon as at a former period. The 

 epithelial cysts, while not so numerous, have not entirely dis- 

 appeared. Those few which remain are smaller and are confined 

 to the lower part of the rectum. 



In an embryo of 99 mm. the transverse colon shows numerous 

 villi arranged in rows, 20 to 25 in number. As seen in figure 

 23, few distinct folds are present, but these do not occur in any 

 definite relation to the villi, that is, the rows of villi and the 

 folds are not alternately placed around the wall of the intestine. 

 From this and from what I have seen in other embryos, it seems 

 improbable that the new \'illi, which are now arising at a very 

 rapid rate, are preceded by folds. More probably they develop 

 after the manner of the villi in the small intestine, as separate 

 growths between the villi already formed. 



Numerous gland buds are also present in the specimen as 

 shown in figure 23. Where the glands are cut in cross section, 

 they show small but distinct lumina, surrounded by columnar 

 cells of the mucous variety, many of which are goblet cells. On 

 the tops and sides of the villi the epithelial cells are 0.022 to 

 0.028 nun. in height while in the glands they are 0.034 to 0.042 



