THE FORMATION OF THE ORGANS THE ALIMENTARY CANAL. 207 



albuminous cells of other Gastropods described above. The yolk- 

 mass, which is still very large, limits directly the lumen of the 

 entoderm-vesicle (Figs. 92 and 93). This latter is already found to 

 be partly filled with disintegrated yolk-substance (Fig. 62 /?), this 

 being taken up by the large entoderm-cells, which, according to 

 BOBRETZKY, represent the rudiment of the liver (Figs. 62, 93 and 

 94, /). The large-celled " hepatic vesicle " may be said to form the 



Fut. 95. J-/>, longitudinal sections through embryos of Nassa mutabilis at different 

 ages (after BOBRETZKY, from BALFOUR'S Text-book), bp, blastopore ; ep, ectoderm ; 

 /, rudiment of foot ; hy, entoderm ; in, epithelium of the enteron ; m, mesoderm ; 

 ./, shell-gland ; st, lumen of the enteron. 



dorsal and posterior part of the entoderm-sac, if the rudiment of the 

 intestine is left out of consideration (Figs. 93 and 94, md). It 

 occupies the left side of the body while the food-yolk is pressed more 

 to the right. From the sections given in Figs. 93 and 94 a good 

 idea of the relative positions of these parts and of the stomach may 

 be gained. The food-yolk still directly limits the lumen of the 

 intestine, but is gradually absorbed as development advances. 



