GLYCOGENIC FUNCTION. 1 75 



genie ferment, which probably (in common with most such 

 ferments) exists in the tissues as a zymogen. It may be con- 

 sidered, therefore, a well established fact that the conversion 

 of glycogen into glucose in the liver and muscles is due to the 

 presence of an enzyme in their tissues. 



Turn now to the mechanism of the oxidation of the sugar. 

 The way to an understanding of the process is paved for us 

 by the knowledge that in various forms of plant and animal 

 life there exist certain unorganized ferments known as oxidases. 

 These have the power of producing certain oxidations that 

 would otherwise not take place under ordinary conditions. 

 A number of observations have been made showing that a 

 body of this class can be extracted from the pancreas and that 

 this body has the property' of oxidizing sugar. Lepine seems 

 to have been the first experimenter to have obtained such a 

 ferment from the pancreas and other observers have confirmed 

 his results. The fact that blood when drawn and exposed to 

 the air has the property of causing the disappearance of sugar 

 corroborates the existence of an oxidizing ferment in the cir- 

 culation. Taking all in all, therefore, there seems ample 

 proof for the statement that the pancreas produces an internal 

 secretion and that this secretion contains an enzyme capable 

 of oxidizing glucose. 



The theory of the glycogenic function ma}' now be formu- 

 lated as follows : The carbohydrates in the alimentary canal 

 are transformed by the digestive juices into, glucose, which is 

 then absorbed and transported to the liver. Here the glucose 

 is transformed by the direct activity of the living cells into 

 glycogen and stored away in that form for future use. When 

 energ}' is required for heat or muscular effort the ferment of 

 the liver is released from its zymogen and acting upon the 

 glycogen converts it into sugar ready for transportation and 

 subsequent oxidation. This glucose is now oxidized by the 

 aid of the internal secretion which the pancreas pours into 

 the circulation. In order to account for the selective oxida- 

 tion which occurs by which the glucose is oxidized principally 



