DEVELOPMENT OF LIVER AND PANCREAS 221 



The liver of another embryo 7 mm. long appears as an anterior 

 and ventral outpouching of the gut. Figure 36 is of a plastic 

 reconstruction of this region of the archenteron. That the con- 

 striction from the gut has proceeded caudally will be apparent 

 by comparison with earlier and later stages. The cavity pro- 

 jecting into the liver-anlage from the lumen of the gut is now 

 much longer, and there are indications of further projections 

 from it on the right side as the lumina of ducts. 



Choronshitzky noted this transverse extension of the lumen 

 in the hepatic anlage of the salamander but did not follow its 

 further history. At the posterior end in the median ventral 

 wall is a marked outpouching which is the gall-bladder {GB, 

 fig. 36). The opening of this outpouching; into the gut is still 

 very wide laterally and shows no differentiation into cystic duct 

 and gall-bladder. The evagination is wide transversely though 

 not extending as far laterally as the liver. In ventral view the 

 gall-bladder appears as a wide transverse outpouching. There 

 is a slight furrow separating it anteriorly and laterally from 

 the liver proper, and a more pronounced one separating it from 

 the caudally placed yolk-mass. 



In an embryo approximately 9 mm. in length (fig. 37) the liver 

 is distinctly further advanced than in the preceding one. The 

 caudal constriction from the gut has progressed rapidly (fig. 4). 

 The original anterior convex surface of the liver has become 

 markedly irregular showing numerous depressions or furrows be- 

 tween projecting masses of cells. Greil ('05) figures a model 

 of the liver in a Bombinator embryo 7.5 mm. long with many 

 secondary buds. A network of veins already occupies the 

 spaces between the hepatic buds but Greil only states that 

 it is present. The anteriorly directed cavity has become con- 

 stricted dorso-ventrally and the division into ducts is more dis- 

 tinct. On the left side (fig. 37) there is a ventral {vl) and a 

 dorsal {(I'm) projection of the lumen. On the right side the ven- 

 tro-lateral extension is prominent. The median ventral evagina- 

 tion {GB) has become more pronounced. There is now the 

 beginning of a lateral constriction of this evagination represent- 

 ing the formation of a cystic duct. The anterior lip of the 



