REFORMATION OF THE CRYSTALLINE STYLE 261 



stance serving to envelop foreign materials thereby protecting 

 the delicate mucous coat of the gills and the intestinal tract. 



Kellogg ('92) raises an objection to the lubricating theory, be- 

 lieving that the crystalline style could not possibly serve as a 

 coating substance for the large quantity of sand taken in by some 

 species of lamellibranchs. Nelson ('18) has shown that the mu- 

 cus which envelops foreign bodies in the stomach of the mollusc, 

 is a product of the glands of the oesophagus, which produce a 

 thick, heavy mucus unlike that furnished by the dissolution of 

 the crystalline style. 



That the crystalline style might function as an alimentary fer- 

 ment was first suggested by de Heide in 1686. That this early 

 conjecture represents the correct interpretation of the significance 

 of the organ in lamellibranchs has been a growing belief among 

 biologists during the past nineteen years. The convincing in- 

 vestigations of Coupin ('00), Mitra ('01), List ('02), Van Rynberk 

 ('08), Gutheil ('11), Nelson ('18), and others have left no trace 

 of doubt as to the true meaning of the crystalline style apparently 

 so necessary to life and the proper functioning of lamellibranchs. 



Coupin ('00) after testing the action of a solution of crystalline 

 styles upon starch material says : 



On peut done conclure, de ces experiences, que la tige cristalline des 

 Acephales est un sue digestif, une sorte de comprime de diastases, eon- 

 tenant beaueoup d'amylase et un peu de suerose, le tout noye dans une 

 matiere muquese, laquelle a sans doute pour but d'empecher la trop 

 rapide dilution de la tige dans I'eau de mer eontenue dans I'estomac, 

 et peut-etre aussi d'agglutiner les matieres solides qui flottent dans 

 celui-ci. 



The weight of authority since 1900 is essentially in accord 

 with Coupin's conclusion that the crystalline style functions as 

 a digestive ferment. Mitra ('01) differed from Coupin in that 

 he believed the crystalline style represented a solid mass of fer- 

 ments. Van Rynberk ('08), by a series of experiments on the 

 crystalline style of Mytilus, confirmed the results of Coupin and 

 Mitra regarding the presence of an amylolitic ferment and con- 

 cluded that cytases and proteases were absent. Nelson -('18) 

 looked upon the crystalline style as a digestive ferment and has 



