544 Franklin P. Johnson. 
and nodules. It has been my fortune to find, in the mid region 
of an embryo of 134 mm., a large persistent intestinal diverticu- 
lum, fig. 28. It resembles in shape the pockets found in the lower 
part of the ileum in the 30 mm. and 37 mm. stages. It is connected 
to the intestinal epithelium by a constricted neck. At its widest 
place it measured .50 mm. in transverse diameter, and at its 
neck .21 mm. Extending outward from its somewhat concave 
outer wall are a number of intestinal glands which are similar 
to those found in other parts of the intestine. Extending into 
its cavity from the internal surface of the outer wall are a few villi, 
one of which is large and extends through the neck of the pocket 
into the lumen of the intestine. 
In the duodenum at 134 mm., several epithelial cysts were 
found, which are entirely cut off from the epithelium of the duo- 
denum. They are spherical in shape, and each has several glands 
extending from its external surface. The flattened cells which 
line these cysts give evidence of an internal pressure. In what 
manner these cysts are formed, I will not venture to say. There 
is, however, the probability of their having developed by the 
persistence of the early duodenal vacuoles or pockets. 
Development of Villi. Koelliker (’61 and ’79) states that at 
the end of the second month and in the third, the beginnings of 
separate villi appear. Barth (’68) and Brand (’77) confirmed this 
view. Voigt (99), working on pig embryos, describes an irregular 
breaking up of the heretofore smooth inner surface of the gut wall 
by means of depressions and furrows. ‘These furrows increase 
in numbers and run together to form a net-work of canals. From 
the fields thus marked off arise slight elevations, the first traces 
of the villi. Berry (’00), studying pig and human embryos, 
writes: 
“The summary given by Oppel shows beautifully the compara- 
tive anatomy of the villi and their evolution. In vertebrates of 
low order, the intestine is smooth, no villi being present. Then 
appear longitudinal folds, and then all gradations between folds and 
villi, and finally villi. It is interesting to note that in those intes- 
tines in which folds of che mucous membrane are present, they are 
more numerous and prominent in the upper part than in the lower 
