258 E. A. BAUMGARTNER 



42 and 46). The pancreatic duct directly divides into two 

 branches, a right and left, which end shortly. The dorsal duct 

 has the same position as in the preceding stage. 



In the following stages there is an increase in the size of the 

 whole pancreas. The dorsal portion comes to lie more and more 

 dorsal to the duodenum and along the right wall of the stomach, 

 while the ventral portion increases in size anteriorly, in front of 

 the anterior duodenal loop. 



A description of the parts in a 35 mm. embryo is given as 

 typical of the further development of the pancreas. In this 

 stage the anterior part of the pancreas lies ventral to the gall- 

 bladder and is embedded in the peripheral part of the liver 

 (fig. 7, .B). This part later probably forms the intrahepatic 

 portion of the pancreas described by Gianelli ('99). Somewhat 

 caudally it is considerably larger in section and separates the 

 liver into dorsal and ventral portions (figs. 11 and 12). In this 

 region just caudal to the gall-bladder the hepatic and ventral 

 pancreatic ducts lie embedded in the pancreas. The pancreas 

 is rather prismatic in cross section, its medial side lying along the 

 right side of the stomach, its lateral dorsal side bounded by the 

 duodenum. Slightly anterior to the ostium of the common 

 duct the pancreas is divided into two masses, one lying ventral 

 and somewhat to the left of the duodenum, the other to the left 

 of the duodenum between it and the stomach (fig. 7, C). This 

 latter mass joins the anteriorly directed portion of the dorsal 

 pancreas. The remainder of the ventral pancreas now lies to the 

 lower right side of the stomach, with a part projecting caudal- 

 ward along the ventral wall of the duodenum (fig. 34). The 

 dorsal pancreas is caudal to the ventral and takes a more dorsal 

 position, until it comes to lie above the duodenum which, has 

 migrated downward. In cross section the dorsal pancreas 

 extends from the lower right side of the stomach almost to its 

 dorsal margin. About half a centimeter from its caudal end the 

 pancreas forms a very small mass, triangular in section, dorsal 

 to the duodenum. 



The ducts of the ventral pancreas of a 35 man. embryo are 

 shown in a graphic reconstruction in figure 34. The ventral 



