DEVELOPMENT OF LIVER AND PANCREAS 253 



figure 26 the lumina of the two veutro-lateral pancreatic diver- 

 ticula open widely into a common lumen which connects dor- 

 sally with the gut-cavity. Anteriorly at about the caudal end 

 of the gall-bladder this lower common lumen is separated from 

 the lumen of the intestinal anlage as shown by the model of the 

 lumina of the ducts (fig. 25) as well as by the figure of a model 

 of the hepatic ducts (fig. 20). In the section figured (fig. 26) 

 the lower part of the right evagination is separated from the 

 main lumen by cells. The next section anteriorly shows the 

 left lumen also cut off. The pancreatic lumina thus very early 

 extend somewhat forward. 



The dorsal pancreatic anlage, as shown by both models (figs. 

 24 and 25), is median and further caudalward than the ventral. 

 As seen in figure 24 it seems to be an elevated portion of the 

 wall of yolk gut. The anterior and posterior furrows separating 

 the anlange from the stomach and gut are not so prominent in 

 this specimen. A model of the lumen shows it to be directed 

 forward (fig. 25). Stohr's statement that there are no evidences 

 of double dorsal pancreatic anlagen in any stages as has been 

 described in the ganoids by v. Kupffer is true also forAmbly- 

 stoma. The dorsal anlage at this time is short in its cranio- 

 caudal diameter. It is, however, further developed than the 

 ventral anlagen. Its ventral margin is limited by a slight groove 

 at the anterior end. Caudally this groove is not present. Figure 

 24 as well as figure 25 shows that there has been quite an in- 

 crease in the dorso-ventral diameter of the intestine. That the 

 ventral part is becoming constricted from the dorsal is shown 

 by both models and was pointed out in the description of the 

 development of the liver. From the anterior end of the ventral 

 part of the gut is the hepatic outpouching, caudal to this and 

 on the right side the gall-bladder, and still farther posteriorly 

 the ventral pancreatic anlagen. Caudal to these evaginations 

 again the gut lumen takes a more dorsal position. 



In 10 mm. embryos the dorsal pancreas is much more promi- 

 nent. The furrow separating it from the stomach is quite deep. 

 Also the caudal furrow is well marked. Mitotic figures are 

 more numerous than before. The cells lining the evagination 



