DEVELOPMENT OF THE ALIMENTARY TUBE AND APPENDED ORGANS. 353 



Histogenesis of the Pancreas. The masses of entodermal cells forming 

 the anlagen of the pancreas develop further by a process of budding, which 

 goes on until finally a compound tubular gland is produced. According to 



FIG. 319. Sections of the developing pancreas of a guinea-pig embryo of 12 mm. (a); 



of 33 mm. (6) ; of Torpedo marmorata (c) . Helly. 



c, Capillaries; Dg, ducts; Gz, duct cells; Lz, Langhans' cells. The cells in c show- 

 distinct zymogen granules 



some investigators the primary evaginations are hollow, their lumina being 

 continuous with the lumen of the gut. According to others they are solid at 

 first and acquire their lumina secondarily. The same uncertainty exists in 

 regard to the later outgrowths or buds. 



