THURLOW C. NELSON. 



depend upon the degree of development of the crystalline style. 

 A period of approximately 74 days were required for complete 

 reformation of the style following the extraction. 



This part of Edmondson's work and the conclusions he draws 

 from it are open to some objection. As the experiments were 

 carried out, there is no way of distinguishing the time actually 

 required for style regeneration from the period of inactivity 

 resulting from the effects of the operation. Out of 147 clams 

 operated upon of which the observation period was in excess of 

 three weeks, only 61, or approximately 42 per cent, survived the 

 operation. Any operative procedure which results in the death 

 of over one half of the animals should be carefully checked before 

 conclusions are drawn from the results, and it seems that such 

 checks were not made. The cut through the mantle alone must 

 seriously have interfered with feeding. Bivalve molluscs are 

 very sensitive to injury and will "sulk" without feeding for long 

 periods after even slight disturbances. 



A much better method of determining the period required for 

 regeneration of the crystalline style would seem to be to determine 

 the rate at which this structure is pushed forward into the 

 stomach and dissolved during the normal feeding of the mollusc. 

 This may be determined readily in forms which like the oyster and 

 fresh-water mussels have a style sac incompletely separated from 



*, > 





FIG. i. The crystalline style of Lampsilis luleola taken from an individual 

 which had been allowed to siphon in water containing a suspension of fine carmine 

 grains. The spiral bands are composed of carmine which was caught upon the gills, 

 carried into the stomach, thence to the intestine from which it was fed across the 

 typhlosoles at two points near the anterior end of the style sac and incorporated 

 into the style. 



