Frederic T. Lewis and Fred W. Thyng 511 
sections. There are four pearls along the anterior limb of the intestinal 
loop. 
At 164 days (H. E. C. 575, 18.8 mm.) there are six pockets, each with 
alumen. The largest of these, 0.1 mm. in diameter, is in the duodenum. 
The others are in the coiled part of the small intestine, separated from 
the first by a considerable interval. They do not decrease regularly in 
size toward the colon. No pockets or pearls were found in the large 
intestine. 
An embryo of 17 days, 22 mm. (H. EH. C. 165), and another of 18 
days, 25 mm. (H. E. C. 168) each show a well-defined pocket in the 
duodenal region and another in the umbilical coils of the intestine, but in 
each case a considerable portion of the intestine has been cut away. 
Two embryos of 20 days, 29 mm., were studied. In Series 170, six 
pockets were found and modeled in wax. They occur at irregular inter- 
vals along the distal half of the small intestine; there is no pocket in the 
duodenum. The models show that the pockets are nodular bulgings of 
the epithelium, quite distinct from folds; they vary in diameter from 
0.05 to 0.16 mm. The other embryo of the same age and size shows only 
three pockets. These are in the distal half of the small intestine. 
A part of the intestine of a rabbit of 41.6 mm. was examined and a 
single pocket found. It is shaped lke a flat, round flask, and is set in 
the epithelium so that it produced only a shght bulging of the basement 
membrane. It has an oval lumen emptying into the intestine, and is 
lined with smooth epithelium, contrasting sharply with the much folded 
intestinal layer which is in process of forming villi. The diverticulum 
is 0.16 mm. in diameter. It shows no evidence of glandular activity and 
is not surrounded by lymphoid tissue. 
The rabbit embryos which have been described indicate that the diver- 
ticula begin to develop at 12 days. They have been recorded as follows: 
Series No. Length. Duodenum. Small! intestine. 
147 5.0 mm. 1 pearl 0 
153 7.5 mm. 1 pocket 3 pearls 
156 10.5 mm. iL te 4 a 
575 18.8 mm. i a 5 pockets 
165 22.0 mm. il 2 1+? “ 
168 25.0 mm. il - Bl oa 
170 29.0 mm. 0 oe 6 be 
url 29.0 mm. Onaers 3 of 
41.6 mm. yey 1+-? “ 
In addition to the rabbit embryos included in this table, 10 others 
ranging from 12 to 22 days were examined, all of which showed at least 
