DEVELOPMENT OF LIVER AND PANCREAS 225 



movement. Then, too, the ventral pancreas forms quite a 

 mass in the median ventral region. Figures 7 A, B and C show 

 the lateral and upward shifting of the posterior portion of the 

 liver. The first drawing in each of the series shows a section 

 taken near the anterior end of the liver which here is median 

 and ventral in position and occupies somewhat more than one- 

 half of the area of a circle. The second drawings in figure 7 

 A and B show a beginning of a depression on the left side caused 

 largely b}^ the change in shape and position of the stomach and 

 duodenum as mentioned above. Figures 8 to 12 are cross sec- 

 tions of embryos 13.5 to 35 mm. in length showing the position 

 of the liver at the level of the junction of gall-bladder and cystic 

 ducts. Here the lateral and dorsal growth of the liver is marked. 

 A somewhat further shifting is shown in the third drawing of 

 figure 7 A and B and the second of 7 C. These sections were 

 taken near the anterior extremity of the gall-bladder. In all 

 of these the liver is crescentic in transsection and extends up- 

 ward almost to the level of the dorsal wall of the stomach. The 

 last drawing in figure 7 shows the relation of parts at the level 

 of the opening of the ductus choledochus in the gut. In all 

 cases a small portion of the liver is found dorsal to the duo- 

 denum in this region of the embryo. In an embryo 45 mm. 

 long the anterior end of the liver is median and ventral as de- 

 scribed above. There is a marked lateral and dorsal growth 

 of the caudal end but in this embryo there is also quite a marked 

 ventral growth which would indicate that from now on the 

 shifting to the right will not be so noticeable, and that there is 

 a growth to the left also. 



4' Development of the biliary apparatus 



a. Description of the hepatic ducts in the adult. A description 

 of the fully formed biliary apparatus may be of interest before 

 describing the development of the hepatic ducts. 



The liver in the adult Amblystoma is a large organ extending 

 fully one-half the length of the abdominal cavity (fig. 13). It has 

 a ventral convex surface conforming to the wall of the abdomen 



