246 E. A. BAUMGARTNER 



later the connection is nearer the cranial end and usually reaches 

 the extreme anterior end. The cranio-caudal growth of the 

 gall-bladder has kept pace with the lengthening and differentia- 

 tion of ducts in the 13 to 14 mm. stage. From the relations in 

 a 15 mm. embryo it appears that the gall-bladder has shifted 

 anteriorly. In this case the hepatic ducts have lengthened more 

 than the gall-bladder. At 20 mm., however, there has been a 

 marked increase in cranio-caudal growth of the gall-bladder so 

 that it is ahnost as long as the ducts. 



Beginning about at this stage the cystic duct is again attached 

 nearer the anterior end of the gall-bladder. This may be taken 

 as evidence that the cystic duct really shifts in its attachment 

 to the gall-bladder. This seems to be borne out in some cases 

 by the fact that its attachment to the hepatic ducts is to a 

 division of the lateral branch of the right lateral ramus instead 

 of to the lateral branch proper. In some cases where the lateral 

 branch is quite long the attachment may have remained to it. 



Whether the gall-bladder originates from the early hepatic 

 anlage or from the gut has caused much discussion. As said 

 before Piper ('02) thought this a matter of interpretation. The 

 more marked furrow caudal to the gall-bladder might be taken 

 as evidence of its belonging to the hepatic anlage, also the fact 

 that the same type of yolk-laden cells form hepatic tissue and 

 gall-bladder. That it, at least is directly caudal to the hepatic 

 anlage is proven by the early connection of its duct to the common 

 bile-duct. 



The connection of the cystic duct probably depends to some 

 extent on the extent of growth and division of the hepatic 

 ducts. It will be remembered that in the earlier stages the 

 cystic duct opens into the common duct, then into the early 

 right hepatic. In the further growth and division of the right 

 hepatic duct the cystic duct becomes attached to one of its radi- 

 cles. As noted above, the cystic duct opens into the lateral 

 branch of the right lateral ramus in all of the embryos studied 

 except one, which was 35 mm. long. 



That there is considerable variation in the relative dorso- 

 ventral position of these main hepatic ducts is to be expected. 



