Fred W. Thyng 493 
wall of the duodenum, a little beyond the duct of the dorsal pancreas, 
and in line with it. Thus it is a dorsal structure. Where the duct of 
the accessory pancreas passes through the intestinal musculature it is 
somewhat constricted, suggesting that eventually it might become sep- 
arated from the intestinal epithelium. This outgrowth has a distinct 
lumen and is somewhat expanded at its distal extremity where the cells 
are of the same nature as those in the other portions of the pancreas. 
So far as known such an accessory pancreas in an embryo has not been 
figured previously. This diverticulum and the small “accessory pan- 
creas ” pictured by Volker (p. 86, Fig. 21) will be discussed in the fol- 
lowing paper. 
Another unusual condition of the pancreas was found in a 12-mm. 
pig embryo where a process of the ventral pancreas extended to the left, 
passing around the ventral side of the duodenum and nearly reaching the 
dorsal pancreas; thus the duodenum was surrounded for more than three- 
fourths of its circumference by pancreatic tissue. This condition sug- 
gests how a ring of pancreas surrounding the intestine may develop 
embryologically. Although I am not aware that such a ring has ever 
been found in the adult pig, Ecker, 62, observed a case in man where the 
head of the pancreas completely encircled the descending part of the 
duodenum. This is a rare occurrence. Apparently only one other similar 
case has been observed (Symington, 85). 
RABBIT EMBRYOS. 
Hammar, 93, in his work upon the development of the liver inei- 
dentally figured the condition of the pancreas, as found in rabbit em- 
bryos of 8 mm. (10 days), 4.5 mm., 5 mm. (11 days), and 8 mm. (Fig. 
1, 2, 3, u. 4, Taf. XI); and in a later paper, 97, he adds a figure of the 
pancreas of a rabbit of 10 mm. 
Joubin, 95, describes the pancreas as found in rabbit embryos of 13, 
14, 15, 18, and 21 days. 
Brachet, 96, has modeled and described the pancreas in embryos of 
104, 114, 124, and 134 days (Plate XVIII, Figs. 4, 5-6, 7, and 8). 
Helly, oz, has modeled the pancreas in embryos of 3.8, 4.8, 5.4, and 
7mm. (Fig. 1-2, 4, 5, u. 6, Taf. XV). He also investigated embryos of 
74 mm., 8 mm., and 3} cm. His conclusions agree essentially with those 
of Brachet. 
The model which I shall describe is from a rabbit embryo of 14 days 
(11 mm.). It shows a more advanced condition of the embryonic pan- 
