260 CHARLES HOWARD EDMONDSON 



material stored up during times of excess nutrition and assimi- 

 lated by the animal when needed. The comprehensive investiga- 

 tions of Barrois ('89-'90), Coupin ('00), Mitra ('00), and later 

 workers have rendered the 'reserve food' hypothesis untenable. 

 It has been pointed out that marine lamellibranchs are never 

 without food except for short durations on the recession of the 

 daily tides, moreover, it is well known that, in case of many 

 marine bivalves, the temporary cutting off of the food supply by 

 the recession of the tide is not followed by a dissolution of the 

 crystalline style or by any marked change in it. The writer has 

 kept Mya arenaria alive for fourteen days without food during 

 which period only slight evidences of dissolution of the crystalline 

 style were detected. 



Coupin ('00), in a summary, says: ''The chemical investiga- 

 tions show that the crystalline style does not contain sugars or 

 fats and only traces of albuminoid materials."^ The same in- 

 vestigator also shows that the crystalline style of Cardium edule 

 when dried weighs but 0.004 gram, and remarks that this would 

 seem an insignificant amount of food for an animal of this size. 



After ably disposing of the 'reserve food' theory championed 

 by Haseloff ('88), Barrois ('89-'90) concludes that the function 

 of the crystalline style is to furnish mucus for the coating of sand 

 grains and other foreign bodies in the stomach thereby preventing 

 injury to the epithelium of the digestive tube as they pass through. 

 Pelseneer ('06) follows Barrois when he says, with reference to 

 the crystalline style: "The product of its solution forms a sort of 

 cement which encrusts any hard substance that may have been 

 ingested and thus protects the delicate walls of the intestine from 

 injury." Coupin ('00), as quoted below, not only ascribes to the 

 crystalline style a digestive function, but suggests a lubricating 

 value when he says that the mucus of the style may agglutinate 

 the solid particles which float in the stomach. 



Schultze ('90) agrees with Barrois, drawing an analogy between 

 the supposed function of the crystalline style and the secretion 

 of certain glands of the larvae of batrachians which furnish a sub- 



1 My translation. 



