272 CHARLES HOWARD EDMONDSON 



maintained. Cilia similar to those of the intestine cover the free 

 ends of the cells of the groove. 



The typhlosoles separating the style sac from the intestinal 

 tract near the stomach wall now become the tjrphlosoles separat- 

 ing the groove from the style sac proper and maintain their 

 relative position and importance, the more prominent one being 

 on the right side. 



Histological preparations of the style sac, by cross-sections 

 through the region of its union with the intestine, give a view of 

 the cells covering the typhlosoles (fig. 8). On the right typhlo- 

 sole, extending nearly one-third the circumference of the tube, 

 the cells are very long, narrow, so closely crowded together that 

 their nuclei have become compressed and are situated at differ- 

 ent levels. The free ends of the cells are provided with a dense 

 layer of cilia somewhat shorter than those covering the cells of 

 the general surface of the style sac. The opposite typhlosole may 

 lack entirely or carry but a small group of these long, narrow 

 cells. The epithelium of the general lining of the style sac con- 

 sists of cells characterized by their uniformity of size, being ap- 

 proximately 0.13- mm. in length and 0.016 mm. in diameter in a 

 medium-sized individual (fig. 14) . In these cells the nuclei are 

 uniformly oval, each with a distinct nucleolus, and are located 

 near the middle region of the cells all approximately at the same 

 level. A basement membrane resting upon a thin layer of loose 

 connective tissue supports the cells. Attached to the free ends 

 of these cells is a very dense layer of strong cilia slightly longer 

 than those carried by the cells of the typhlosoles. In a medium- 

 sized individual the cilia of this dense layer measure about 0.04 

 mm. in length or one-third the length of the cells which bear them. 



The cytoplasm of the cells just described is granular and often 

 their free extremities are crowded with minute granules of brown 

 pigment. Sabatier ('77) concludes that this brown, granular 

 pigment, characteristic of the cells of the general surface of the 

 style sac, is derived from the substance of diatoms, protozoa, etc., 

 collected between the crystalline style and the epithelium, of the 

 lining of the tube and squeezed out by the action of the strong 

 cilia. This involves the function of the crystalline style as pro- 



