WILLIAMS: GLYCOGENIC FUNCTION IN THE MOLLUSCA. 37 



the pancreatic secretion of Sepia. And that the glycogen is 

 immediately formed from the ingesta, as in the Vertebrates, has 

 been proved by Barfurth^° Avho found that after three hours 

 fasting it had disappeared from the Hver of Helix, but that it 

 reappeared from nine to ten hours after feeding, and by 

 Hammarsten^^ in the decrease in the amount of glycogen 

 showed in the liver of his pomatias which had hibernated in a 

 warm room. Thus there is every reason for us to believe, in 

 the face of no evidence to the contrary, that the mother-substance 

 of glycogen in the Mollusca is the same as that in the 

 Vertebrates — viz : the carbohydrates and proteids of their food- 

 stuffs. 



Regarding the ultimate destination of the glycogen in the 

 Mollusca we have very little evidence to guide us to a safe 

 conclusion. In the Vertebrates it is no doubt devoted to the 

 production of heat and muscle-energy. Broken up, in then, 

 by a blood-ferment again into sugar, as the exigencies of the 

 system demand, it is taken by the hepatic veins to undergo 

 metabolic changes in the tissues. And that it is, in them, used 

 up during muscular contractions does not admit of a doubt for 

 it has been experimentally proved that all the glycogen dis- 

 appears from the muscles during movement. While Barfurth 

 has stated {Joe. cit.) that the quantity present in the muscles of 

 Helix is inversely proportional to their activity, and should 

 Wooldridge's theory that the Vertebrates blood-ferment is 

 lecithin prove to be a fact we have here two things that unite 

 together to show, disregarding the facts we have already 

 mentioned, that glycogeny in the Mollusca and the Vertebrata 

 are far from being dissimilar, since lecithin is present in the 

 Molluscan blood. But, whatever its destination in the Mollusca 

 may be, it is a point well worthy of mention in relation with 

 this, that a large amount of reserve-material must be stored away 



10. loc. cit. ; also " Das Glycogen in der Gasteropodenleber." Zool. 

 Anz. pp. 652-655. 



11. loc. cit. 



