290 CHARLES HOWARD EDMONDSON 



2. After the extraction of the crystalhne style of Mya arenaria, 

 a new style is competely reformed in the proximal portion of the 

 style sac in a period of about seventy-four days, when condi- 

 tions are most favorable. 



3. At the end of the fourth day after the extraction of the crys- 

 talline style, the beginning of a new style may be observed in the 

 style sac. It consists of a delicate sheath of mucus enclosing a 

 core of food material and lies on one of the typhlosoles, usually 

 the right which, in Mya arenaria, is the most prominent. 



4. Growth of the crystalline style progresses more rapidly dur- 

 ing the summer than the winter months. The increasing vitality 

 of the mollusc preceding the spawning period, which occurs late 

 in August and early September, may be accountable, in part at 

 least, for the more rapid development of the crystalline style 

 during the spring and summer. Climatic conditions are also more 

 favorable for growth during the summer season. 



5. A crystalline style is reformed, under favorable conditions, 

 in the short, distal portion of the style sac which is entirely sepa- 

 rated from the proximal division by the operation. This obser- 

 vation proves conclusively that the epithelium of the style sac 

 is the source of the crystalline style. 



6. In the reformation of the crystalline style of Mya arenaria 

 an axillary food core is usually present, but disappears with the 

 complete development of the organ by the gradual movement of 

 the latter into the stomach. No food core exists in the fully 

 developed crystalline stjde of this species. 



7. After the removal of the crystalline style, Mya arenaria 

 may exist for more than thirty days without ingesting food, if 

 replanted under normal conditions, during which time the crys- 

 talline style is reforming. 



The ingestion and digestion of food is apparently dependent 

 upon the degree of development of the crystalline style, since not 

 until the organ reaches a state of sufficient maturity to be pro- 

 jected into the stomach does the ingestion of food occur. 



8. Mya arenaria may be kept alive out of water and without 

 food for fourteen days after the extraction of the crystalline style. 

 Under these conditions a new crystalline style makes its appear- 



