.69 



test first for sugar in the reagents. At the end of the 

 time some of the starch had been hydrolysed, and the 

 solution now reduced Trommer's and Fehling's solutions. 

 The phenyl hydrazine test also indicated the presence of 

 sugar. 



Mitra was the first to show that the crystalline 

 style contained a digestive ferment (26), which was able 

 to convert starch and glycogen into sugar. He assumed 

 from this that the work of the crystalline style was that 

 of a ferment. Xow, tliough I have found the ferment in 

 the styles of Pecten, the amount of starch which was 

 hydrolysed was small, and it is possible, especially if the 

 style be regarded as a secretion of the digestive gland, 

 that the presence of a ferment is accidental. 



With regard to the question of the origin of the 

 style, the tricuspid body and the latter have exactly the 

 same structure, and in some specimens appeared to be 

 continuous. Further, the tricuspid body is in close 

 connection Avith the lining of the stomach and extends 

 into the pockets and openings of the ducts from the 

 digestive gland. I think it probable, therefore, that the 

 style is secreted by the digestive gland. The cells of the 

 alimentary canal, with their long cilia, have not exactly 

 the appearance of secreting cells. 



AVith regard to the various theories named above, 

 there are serious objections to most of them. The style 

 cannot, moreover, be looked upon as a rudimentary 

 structure, since the compartment of the intestine in which 

 it is lodged, and the special caecum of the other lamelli- 

 branchs are lined with better developed cilia than the rest 

 of the alimentary canal. The theory of Barrois (23) that 

 diatom frustules, &c., are encased by the substance of the 

 style seems hardly sufficient reason for the development 

 of a special caecum and style, when there is no such organ 



