220 



E. A. BAUMGARTNER 



Weysse did not follow the development beyond a very early 

 stage. 



In an embryo approximately 5 jnm. (fig. 2) long the anterior 

 wall of this early ventro-caudal projecting cavity has become 

 more prominent. The extension of the gut-lumen into this out- 

 pouching is a large cone-shaped cavity somewhat flattened in 

 transection. The columnar epithelial cells lining it are now- 

 found farther caudal ward than in the preceding stage. 



Fig. 3 Sagittal section of an embryo almost 7 mm. long. X 30. D.choL, 

 ductus choledochus; F.g., foregut; G. caudal extension of gut; G.B., gall-bladder; 

 He, heart; Li, liver; Y, yolk mass. 



In a sagittal section of an embryo 7 mm. long there is shown 

 a more advanced stage of the condition just described. From a 

 comparison of this stage (fig. 3) with the previous one and the one 

 following, it will be seen that the hepatic anlage has become more 

 prominent by a cranio-caudal constriction from the gut. Folds 

 have begun to form on the outer surface of the liver. The cav- 

 ity of the hepatic diverticulum is widely connected with that 

 of the gut. In the ventral, wall there is a slight median depres- 

 sion (GB) which is the earliest indication of the gall-bladder. 

 This depression is at the caudal end of the liver-anlage in the 

 region where the primitive ductus choledochus is forming. 



