288 CHARLES HOWARD EDMONDSON 



the cilia of this layer are to be regarded as the means of proper 

 stomach trituration to assist the action of the gastric juice. "^ 



List ('02) expressed his belief, after observing the formation of 

 the crystalline style numerous times, that the long narrow cells 

 of the typhlosoles were the source of the organ. In regard to 

 the shorter cells of the general lining of the style sac, List states 

 his opinion in the following words : 



Seine Function beruht nach meiner Ansicht vornehmlich darin, den 

 Krj^stallstiel in eine drehende Bewegung zu versetzen, wodurch einer- 

 seits der regebnassige concentrische Schichtenbau bedingt wird und 

 andrerseits ein stetiger Nachschieben in den Magen. 



The assumption of List, as indicated by the above quotation, 

 that the strong cilia of the shorter cells cause the crystalline style 

 to rotate and to be gradually projected into the stomach, was 

 entirely verified by Nelson ('18), who actually observed the rota- 

 tion and the movement of the crystalline style into the stomach 

 in Modiolus. 



Biedermann ('10-' 11) doubts that ciliated epithelium can have 

 a secreting function, and is inclined toward Mitra's view that the 

 crystalline style represents in reality a condensed product of the 

 secretion formed by the liver. 



Gutheil ('11), in answer to Biedermann, contends that there is 

 no difference between secretion and absorption except in the 

 direction of movement of the material, and points out that the 

 intestinal tract is ciliated throughout and is an absorbing surface, 

 therefore, ciliated epithelial cells may also secrete. Nelson ('18), 

 from observations on species with the style sac incompletely 

 separated from, the intestine, concluded that the cells of the 

 typhlosoles were the source of the crystalline style. 



The chief morphological characteristics of the cells of the style 

 sac of Mya arenaria have been mentioned above. On the right 

 border of the groove the long, narrow cells, with nuclei at various 

 levels and which Sabatier ('77) termed the white epithelium, are 

 sharply contrasted with and abruptly merge into the general 

 lining epithelium of the style sac, as has been described above. 



Transverse sections of the style sac together with the intestinal 

 tube just below the stomach floor, stained in mucicarmine, re- 



