70 



in ascidians, ecliiiiodermata or ^^()l•ms, wliich have 

 similar food matters. 



The nature of the style is decidedl}' not that of a 

 reserve food material, and it seems difficnlt to comprehend 

 why, under normal conditions, marine lamellibrauclis 

 should require to make provision for times of starvation. 



Barrois, who rejects the theory of reserve food 

 material, states that he was never able to detect a 

 diminution in the styles at various seasons nor even after 

 keeping specimens of Cardium in filtered water for some 

 days. Both Mitra's experiments and my own confirm 

 Hazay and Haseloif (24 and 25) as far as this is concerned, 

 and the chief objection to the reserve food stutf theory 

 must be the composition of the style itself. The position 

 of the style and its composition tell strongly against the 

 theory of it being an excretion. When the animal is 

 kept under such .conditions as described by Mitra, is it 

 absorbed by the animal or simply dissolved away by 

 water passing through the alimentar}' canal ? Possibly 

 it is absorbed and the ferment used for converting the 

 glycogen (which is stored up in large quantities in most 

 lamellibranchs) into sugar. 



The development of a caecum certainl}' points to a 

 storage for some purpose. There is no doubt that in 

 Pecten, where the style seems to occupy the whole area 

 of the intestine, it hinders the food from passing too 

 quickly through the alimentary canal, and provides an 

 additional surface over wliich its contained amylolytic 

 ferment can act. It must be remembered, however, that 

 the presence of this ferment in the style is not conclusive 

 proof that the style has been evolved as a ferment or 

 method for storing a ferment. 



It has been already stated that the last portion of 

 the intestine passes through the pericardium and the 



