346 RICHARD E. SCAMMON 



ing the single median pouch already mentioned which now pro- 

 jects downward from the floor of the fore gut. Continuous with 

 the median pouch thus formed are the middle parts of the diver- 

 ticula which are expanded laterally and dorsally and which will 

 be referred to hereafter as the lateral hepatic pouches. The 

 lateral hepatic pouches extend backward as far as the anterior 

 wall of the yolk-stalk, and there become continuous with the 

 posterior parts of the lateral diverticula which remain almost 

 unchanged from their slightly expanded condition of earlier stages, 

 and which will he referred to as the pars ductus, as it is from them 

 that the major portion of the ductus choledochus is formed. The 

 left lateral pouch becomes continuous with the pars ductus 

 of that side without any distinct line of demarcation. On the 

 right side, however, the pouch ends abruptly by projecting 

 nearly at right angles from the gut wall. Deep grooves, of which 

 the left is the more pronounced, intervene between the latter walls 

 of the ventral part of the fore gut and the mesial walls of the dor- 

 sally growing lateral pouches. These indicate the beginning of 

 the process by which the liver will be eventually cut off from the 

 gut tube above. The gall bladder is present as a deep ventral 

 pouch, lying between the median liver pouch in front and the 

 anterior wall of the yolk-stalk behind. Its walls are directly 

 continuous with the ventral part of the liver pouch and the pars 

 ductus above, but a slight longitudinal groove marks the bound- 

 ary between the structures. This groove becomes deeper as it 

 proceeds anteriorly until a point is reached about one-fifth of the 

 length of the pouch from its anterior wall. Here the groove is 

 entirely absent and there is thus left a small anterior expanded 

 segment of the gall bladder stalk which is the anlage of the primi- 

 tive cystic duct. A point worth emphasis is that the entire 

 liver anlage shows a slight rotation to the left and that the left 

 lateral liver pouch shows a greater dorsal growth than does the 

 right. The para-archenteric grooves have remained unchanged. 

 The changes which now follow are those of passive growth. 

 The lateral pouches expand transversely and become almost 

 globose in outline. At the same time there is a slight growth 



