236 E. A. BAUMGARTNER 



In the ventral view of the model of a 14 mm. embryo (fig. 39) 

 the relation of pancreatic duct to the common duct is shown. 

 The short thick common duct divides into right and left hepatic 

 ducts (figs. 39 and 40). They lie in almost the same horizontal 

 plane and are of about the same diameter, but the right is the 

 shorter, dividing almost immediately into its lateral and medial 

 rami. In a 13.5 mm. embryo (fig. 41) the right hepatic duct is 

 of larger diameter than the left. In a 15 mm. embryo the com- 

 mon duct is very short (fig. 42). The right and left hepatic 

 ducts here are very long as compared with those in other embryos. 

 The left duct has come to lie in a more ventral plane due to the 

 shifting of the whole posterior part of the liver and gall-bladder 

 to the right. The same is true to a greater extent for the left 

 ducts in the 20 and 35 mm. embryos (figs. 43 and 44). In a 20 

 mm. embryo the right hepatic duct is the shorter as it is in a 

 35 mm. embryo. In a 35 mm. stage the left hepatic duct is 

 almost ventral to the right. The same holds true for a 45 mm. 

 embryo. In the adult, however, the left duct is again more 

 lateral to the right, but still somewhat more ventral. 



d. Developmeyit of the minor hepatic ducts. Right lateral ramus. 

 The right hepatic duct in a 14 mm. stage is divided into lateral 

 and medial rami and the right lateral ramus is subdivided into 

 lateral and medial branches (fig. 39). The short cystic duct 

 is attached to the lateral branch. The medial branch (fig. 40) 

 gives off several tubules in an oblique dorso-ventral plane. In 

 a 13.5 mm. embryo the right lateral ramus is quite ventral to 

 the medial one (fig. 41). As in the earlier stage, it is divided 

 into lateral and medial branches. The cystic duct which is now 

 directed almost horizontally, is attached to the right side of 

 the lateral branch. The anterior portion of the lateral branch 

 anastomoses with a duct from the right medial ramus. In a 

 15 mm. embryo (fig. 42) the right lateral ramus is shorter than 

 in the preceding specimen. The right hepatic duct is, however, 

 longer so that the cystic duct is attached to the lateral branch 

 farther from the gut. The lateral branch here divides into dor- 

 sal and ventral branches. In a 20 mm. embryo the right lateral 

 ramus is very short (fig. 43). In position it is now somewhat 



