492 Pancreas in Embryos of the Pig, Rabbit, Cat, and Man 
The second model (Fig. 2) represents the pancreas in an embryo of 
20 mm. (H. E. C. 60). It is figured somewhat ventrally from the right 
side. It represents a much more advanced condition of the pancreas than 
that seen in Lewis’ reconstruction of the 12-mm. pig embryo, but corre- 
sponds in many ways to Volker’s description of embryo XIII (02, p. 87). 
The common bile duct (D. chol.) enters the intestine a little beyond 
the pyloric end of the stomach (St.). The duct of the ventral pancreas 
(D. panc. v.) will be observed to have the same relation to the common 
bile duct as already shown in Fig. 1. As in the earlier stage the distal 
end of the ventral pancreas is in relation with a subdivision (x) of the 
dorsal pancreas. Although the relation has become more intimate an 
actual anastomosis on the right side of the vitelline vein has not yet 
occurred. The great change in relations in Fig. 2, as compared with 
Fig. 1, has accompanied the development of the duodenal loop of the 
intestine. 
The portion of the intestine to which the duct of the dorsal pancreas is 
attached has been carried ventrally, and the duct of the dorsal pancreas 
now passes across the ventral pancreas on the median side of the latter. 
The two portions of the pancreas are in very close relation at their place 
of crossing, but in this embryo anastomosis between them has not oc- 
curred. Later, according to Volker, the dorsal pancreas fuses with the 
ventral at this point. This fusion sometimes takes place sooner than the 
anastomosis through the process (a) on the right of the portal vein; 
sometimes later. By the crossing of the dorsal pancreas with the ventral, 
the portal vein becomes surrounded by a ring of pancreatic tissue, the 
“anneau periveneux” of authors. 
Stoss’ observation, 91, that in the adult pig only the duct of the dorsal 
pancreas persists, receives confirmation from the investigations of Wlas- 
sow and Volker. Both found embryological evidence that after the dorsal 
pancreas had anastomosed with the ventral, the connection with the com- 
mon bile duct atrophied, leaving only one pancreatic duct, that of the 
dorsal pancreas. 
The outlet of the duct of the ventral pancreas has become obliterated 
in pigs of 24 mm. as seen in the Harvard Collection. The position of 
the remainder of this duct is indicated in the adult pig by a lobe of 
pancreas which extends nearly to the bile duct. The pancreatic ring 
about the portal vein is retained. ‘Two lobes extend distally from the 
Ting, corresponding with the dorsal and the ventral pancreas of Fig. 2. 
An interesting feature of the model of the 20-mm. pig (Fig. 2) is the 
presence of an accessory pancreas (Pan. acc.). It arises from the dorsal 
