108 THURLOW C. NELSON 



ism was found best developed in those species, like Modiolus, 

 in which little discrimination is shown by the gills, palps, and 

 mantle. 



The actual rotation of the style was observed, and is here 

 described for the first time. This movement of the style is of 

 great importance in separating the food from foreign particles 

 and in serving as a substitute for peristalsis. 



The gastric shield is shown to be an organ for the protection 

 of the gastric mucosa against the abrasive action of the head of 

 the revolving style. 



In those species in which the style sac is incompletely sepa- 

 rated from the intestine, the style serves as a means of restoring 

 to the stomach undigested food particles which might otherwise 

 be lost. 



The conclusions of Coupin ('00), that the style contains strong 

 amylolytic ferments, have been confirmed. These enzymes are 

 held in a stiff gelatinous matrix of a globulin-like substance. 



In some of the boring molluscs the style attains a relatively 

 great size, thus representing a large mass of enzyme for imme- 

 diate use. 



The conclusions of Mitra ('01), regarding the style as solely 

 a mass of pure enzyme secreted bj^ the hepatopancreas, and the 

 theory of the protective action of the style substance, held by 

 Barrois, Pelseneer, and others, are hereby rendered untenable. 



BIBLIOGRAPHY 



Allen, W. R. 1914 The food and feeding habits of fresh-water mussels. Biol. 



Bull., 27, 127-139. 

 Barrois, Th. 1889-90 Le stylet cristallin des Lamellibranches. Revue biol 



Nord France, 3, 4, 124-141, 161-169, 263-271; 5, 209-226, 299-311, 



351-357. 

 Berxard, C. 1855-66 Legons de physiologic experimentale appliquee a la 



medicine. 2, 488-498, Paris. 

 BiEDERMAN, W. 1910-11 Die Aufname, Verarbeitung, und Assimilation der 



Nahrung. Handb. d. vergl. Physiol. H. Winterstein, 2, 929-1040, 



Jena. 

 Blainville, H. M. D. de 1825-27 ^Vlanuel de Malacologie, 123-155, Paris. 

 Blanchard, E. 1861 Organisation du regne animal, mollusques acephales. 



Paris. 



