CRYSTALLINE STYLE OF LAMELLIBRANCHS. 89 



the intestine. A weak suspension of finely divided carmine if 

 added to a water rich in food materials will usually be ingested 

 along with the food and may be incorporated into the style. In 

 some instances the carmine is passed across the typhlosoles into 

 the base of the style sac and results in a red style. In others, the 

 carmine may be fed into the style sac at some point between the 

 stomach and the base of the sac, in which case the carmine forms 

 a spiral band about the style as it is rotated and pushed anteriorly, 

 giving the effect of a barber's pole (Fig. i). Allen ('21) records 

 a similar observation in a fresh-water mussel where minute green 

 organisms took the place of the carmine. 1 



Complete regeneration of the crystalline style in Ostrea, 

 Modiolns, Anodonta, and Lampsilis will take place at summer 

 temperatures in from approximately 15 minutes in the oyster to 

 a few hours in the other genera. Allen ('21) finds style regener- 

 ation in fresh-water mussels in about 24 hours. It is difficult to 

 believe that a process which occurs in at the most a few hours in 

 many of our common bivalves should require two and a half 

 months in an active rapidly growing mollusc such as Mya. 

 Although I have had no experience with this form, it would seem 

 possible to inject by means of a hypodermic syringe a small 

 amount of carmine in sea water near the base of the style sac and 

 to determine the speed at which this pigment, incorporated into 

 the style, is carried toward the stomach. If carefully performed 

 such an operation should be far less drastic in its effects than was 

 the technique employed by Edmondson. 



In their admirable work on the natural history and propagation 

 of fresh-water mussels Coker and his associates ('21) accept the 

 conclusions of my 1918 paper, but contribute no original obser- 

 vations regarding the function of the crystalline style. Included 

 in the former paper, pp. 88-91, are the observations of Dr. Franz 



1 While this paper was in press I received a copy of the report of Dr. J. H. Orton 

 '24 on the causes of unusual mortality among oysters on English oyster beds; 

 Ministry of Agriculture and Fisheries, London. On page 54 of this report is figured 

 the crystalline style of Ostrea edulis, bearing a spiral band of food organisms. In a 

 footnote on the same page this author suggests that one function of the style is "the 

 mechanical one of drawing the mucous strings enveloping the food material into the 

 stomach by twisting the strings around the shredded revolving head of the style like 

 a capstan." In my 1918 paper, pg. 101, it is observed that "so strong is the 

 tractive force of the rotating style that strings of mucus from any part of the body 

 if led to the stomach cavity, are at once drawn in and wound up in the food mass." 



