PRODUCTION OF STJGAB IN THE LIVEK. 321 



This must be due to some ferment remaining in the tissue ; 

 and Bernard has, indeed, been able to isolate a principle 

 which exerts this influence in a marked degree. If an 

 opaline decoction of the liver be allowed to stand until it has 

 become entirely clear, showing that all the glycogenic mat- 

 ter has been transformed into sugar, and alcohol be added 

 to the liquid, the hepatic ferment will be precipitated. This 

 may be redissolved in water, and it effects the transforma- 

 tion of starch into sugar with great rapidity. 1 



From these facts it is pretty conclusively shown that the 

 following is the mechanism of the production of sugar in the 

 liver : 



The liver first produces a peculiar principle, analogous 

 to starch in its composition and in many of its properties, 

 though it contains two atoms more of water, out of which 

 the sugar is to be formed. The name, glycogenic matter, 

 may properly be applied to this substance. It is, as far as is 

 known, produced in all classes of animals, carnivora and 

 herbivora ; and though its quantity may be modified by the 

 kind of food, its formation is essentially independent of the 

 alimentary principles absorbed. 



The glycogenic matter is not taken up by the blood as 

 it passes through the liver, but is gradually transformed, in 

 the substance of the liver, into sugar, which is washed out of 

 the organ as fast as it is produced. Thus the blood of the 

 hepatic veins always contains sugar, though sugar is not 

 contained in the substance of the liver during life. 



Variations in the Glycogenic Function. 



In following out the relations of the glycogenic process 

 to the various animal functions, Bernard studied very closely 

 its variations at different periods of life, with digestion, the 

 influence of the nervous system, and other modifying condi- 

 tions. He made some of his observations by examining the 



1 BERNARD, op. ezz., p. 124. 

 21 



