230 E. A. BAUMGARTNER 



even two divisions further removed from the common duct, 

 as shown in figure 17 and 44. In a graphic reconstruction of 

 the biliary apparatus of a 7 cm. embryo (fig. 15) the cystic 

 duct joins the right lateral ramus as is shown also in figure 43. 

 The hepatic radicle to which the cystic duct is attached shortly 

 divides into trabeculae beyond this point. The right medial 

 hepatic ramus divides and subdivides into branches as shown 

 in figure 14. Its branches sometimes anastomose with the 

 branches of the right lateral or left medial ramus (fig. 17). 



The left hepatic duct is generally shorter and of slightly smaller 

 diameter than the right one, as well as more ventral in position. 

 It is divided as the latter into lateral and medial rami. The 

 left medial ramus sometimes joins the right medial ramus as 

 shown in figure 16, and this duct then subdivides as a single 

 one. Frequently, however, the left medial ramus runs anteriorly 

 subdividing into smaller branches of which some may anasto- 

 mose with those of the right medial (fig. 17). The left lateral 

 ramus is shortly divided into two of which the lateral either 

 turns caudally (fig. 44) or sends out branches that go to the 

 posterior portion of the longer left lobe. 



b. Development of the ductus choledochus. The ductus chole- 

 dochus in 9 mm. embryos is still very wide and short. The origi- 

 nal caudalward projection from the gut cavity has disappeared 

 and there is only the anteriorly directed common duct. In a 

 model of an embryo 9 mm. long the ductus choledochus is wide 

 transversely but constricted dorso-ventrally (fig. 37 and 38). 

 It is attached at the anterior side of the now ventrally directed 

 gut. At 11 mm. the duodenum has turned ventrally and folded 

 to the right. A very much constricted and short common 

 duct is attached to its superior anterior surface. In a 13 mm. 

 embryo the conmion duct is attached to the anterior surface 

 of the cranial fold of the duodenum. As before, the duct is 

 small and short, soon dividing into right and left hepatic ducts. 

 The epithelial lining of the duct still contains yolk-granules 

 and except for a quite irregular but prominent lumen is very 

 much like the hepatic ducts. Indeed the difference in the 



