ON THE STRUCTURE OF iENTGMA ^NIGMATICA. 287 



that tlie thick, cuticle-like lining of the stomach, the "fleche 

 tricuspide " of Poli, corresponds exactly in extent to the area 

 in which the yellow glandular cells occur, and is not present 

 in the roof and upper portion of the left wall where these 

 cells are absent, A series of transverse sections shows that 

 the thick glandular tract of the stomachal epithelium is con- 

 tinued posteriorly into the c£ecum of the crystalline style, 

 while the ciliated non-glandular tract of the roof and left side 

 passes into the small intestine, and at the entrance into the 

 latter is thrown into a number of stout, ciliated ridges which 

 form a straining apparatus, and are continued into the four 

 prominent ridges projecting into the lumen of the intestine. 

 The transition from the glandular epithelium of the floor of 

 the stomach into the characteristic epithelium of the cfecum 

 of the crystalline style is a gradual one ; the ciliated cells of 

 the stomach gradually become shorter and stouter, the yellow 

 gland cells gradually become scarcer, until shortly after its 

 origin from the stomach the c£BCum is lined exclusively by 

 the epithelium shown in fig. 22. I have shown (3) that in 

 Jousseaumia there is a similar localised tract of glandular 

 cells in the stomach passing through a similar transitional 

 epithelium into the cfecum of the crystalline style, and I have 

 suggested that the last-named structure is secreted by the 

 gland cells in question. 



Our knowledge of the structure and functions of the 

 " fleche tricuspide " and the crystalline style is due to the 

 researches of Barrels (2), List (10) and Mitra (11). Thanks to 

 the last author, we know that the style consists of a proteid 

 material belonging to the globulin class, and that it contains 

 an active amylolytic ferment. He supposes, without giving 

 any very cogent reasons for his conclusions, that the sub- 

 stance of the style is secreted by the liver, and is stored up 

 as a flexible solid in the c?ecum, or in some forms, in a special 

 compartment of the stomach or intestine. Barrois has care- 

 fully investigated the structure of the "fleche tricuspide" of 

 the stomach and the crystalline style in Donax trunculus, 

 and has entered much more fully into the histology of the 



