CRYSTALLINE STYLE OF LAMELLIBRANCHS. 87 







its base and is built into the soft core of the style. I have found 

 oysters in which the entire core of the style was almost a solid 

 brown mass of Glenodiniiim. In this position food materials at 

 first rejected from the stomach in the separation of inert ma- 

 terials may be recovered as the style is moved gradually forward 

 into the stomach. 



In the interval since this paper, Nelson, /. c., was published 

 there have appeared several noteworthy contributions to the 

 knowledge of the physiology of digestion in bivalve molluscs, and 

 of the function of the crystalline style. It is well therefore to 

 review these at this time and to give such additional information 

 as has been accumulated during the past seven years in order that 

 the present status of the problem of the crystalline style may 

 readily be ascertained. 



Edmondson ('20), in a detailed and very well illustrated paper, 

 describes the reformation of the style of Mya arenaria following 

 its extraction. Among the species of bivalves which occur on the 

 northwest coast this investigator found in Cardium corbis, 

 Saxidomus giganteus, S. mittallii, and Paphya staminea, that 

 starvation or removal from the water resulted in dissolution of 

 the style "within a few days at most." In other species, notably 

 Siliqna patula, Schizothcerus nuttallii, Macoma nasuta, the style 

 was found to be far more resistant to dissolution, being present 

 even at death through starvation. In Mya only slight disso- 

 lution of the style occurred even after 14 days out of water. 

 (Contrast this with the oyster, in which dissolution of the style 

 occurs while the molluscs are exposed during the low tide; 

 Nelson, '18.) As Edmondson points out,' the forms with resistant 

 styles possess a style sac nearly or completely separated from the 

 intestine. 



Experiments were performed with Mya in which the mantle 

 was cut in the midline along the ventral surface for a distance of 

 15 to 25 mm. posterior to the pedal opening. A transverse cut 

 was made near the middle of the style sac and the style extracted. 

 The clams were then planted out and the rate of regeneration of 

 the style studied. No food was taken apparently until the style 

 was sufficiently regenerated to project into the stomach, from 

 which Edmondson concludes that ingestion and digestion of food 



