CRYSTALLINE STYLE OF LAMELLIBRANCHS 59 



Milne-Edwards ('59) believed that its function was to slir 

 the contents of the stomach during digestion. Hessling in the 

 same year agreed with him that the style was an epithelial 

 secretion. Both evidently were ignorant of the earlier work of 

 Huxley. 



Vanstone ('93) thought that the style was homologous with the 

 stomach plates of snails and served to grind up the food. 



Sabatier ('77), in his monograph of the common mussel, gives 

 the first exhaustive histological treatise on the style region. He 

 recognized the two ridges, or 'typhlosoles,' incompletely sepa- 

 rating the style sac and intestine, and their relation to the 

 style. His study of the heavy ciliation of the wall of the style 

 sac led him to believe that the food of the mussel was caught 

 between the cilia and the style, and mixed and rolled around, 

 the style playing the part of an organ of mastication. He con- 

 sidered that the epithelium of the style sac served for the ab- 

 sorption of dissolved matter. He did not suspect the real rela- 

 tion between the style and the secretory epithelium which he 

 describes. 



C. An aid to absorption. Krunkenberg ('86) considered the 

 style to have a function similar to that of the typhlosole of 

 Lumbricus, pressing the alimentary matter against the absorbing 

 epithelium. Von Fiirth ('03) agrees with this interpretation of 

 the anatomical function of the style. Grave ('03) believed that 

 the style of the oyster acts as a plug to prevent the too rapid move- 

 ment of alimentary materials and to exclude foreign particles of 

 large size from the intestine. 



D. Reserve of nutriment. Hazay ('81) made detailed observa- 

 tions of the occurrence of the style in the Unionidae, and distin- 

 guished the 'Knorpelstiel,' the gastric shield, and a hyaline 

 string, the 'Diinndarmkorper,' or style proper. According to 

 his observations, the gastric shield is very rudimentary in the 

 spring and summer, attaining its greatest size in the autumn. 

 The style is, in his opinion, formed from a gelatinous mass 

 ('Magengallerte') in the stomach, and is pushed back into the 

 intestine where it remains as a reserve of nutriment. This is 

 kept from flowing into the stomach by the presence of the gastric 



