244 E. A. BAUMGARTNER 



and final division these branches are the same as the right 

 medial and left medial rami. As will be seen in figures of 

 the different models, the smaller embryos did not have all of 

 the divisions and subdivisions marked in the tables. In figure 

 39, for instance, the right branch of the common medial ramus 

 shows no further division, the left branch only one. Further 

 division of both is seen in the 20 mm. stage (fig. 43). The 

 division here, however, is more into dorsal and ventral radicles, 

 due to the more marked lateralward shifting of the liver and the 

 ducts. The extreme of this lateral shifting is seen in figure 44, 

 where the left hepatic duct is almost ventral to the right. The 

 left lateral ramus in a 45 mm. embryo does not hold such a 

 ventral position with reference to the left medial. 



There seems to be no definite rule in regard to the anastomos- 

 ing of ducts. In a 35 mm. embryo they are the most frequent 

 and here apparently because the ducts were crowded so close 

 together. That the right and left medial rami sometimes join 

 and form one duct is seen in the models of a 14 and a 20 mm. 

 embryo, also in the graphic reconstruction of a 7 cm. and 10 

 cm. Amblystoma. It would seem this fusion of the ducts is 

 quite probably du£ to crowding. 



The definite position of the hepatic ducts with reference to 

 the portal vein is seen for all embryos (figs. 8 to 12). The same 

 relation is also found in the adult. As a rule there is a branch- 

 ing of the hepatic ducts corresponding to the division of this 

 vessel. In the developing embryo the ducts are found usually 

 to the right of and ventral to the portal vein. 



From the usual description of the biliary apparatus in the 

 frog it would seem that there is a fairly close correlation in the 

 main features between these two amphibians. The figures of 

 Ecker, Wiedersheim and others show a gall-bladder connected 

 to a right hepatic duct. There is also a left hepatic duct, the 

 two uniting in the pancreas and forming a ductus choledochus 

 which, as usually described, is joined by the pancreatic duct. 

 In no case in Amblystoma were two cystic ducts found as is shown 

 for the frog. The di\dsion into rami in the frog as far as the ducts 

 have been figured, seems to be somewhat different from that 



