CH. XXXIII.] GLYCOGENIC FUNCTION 515 



nating frog the amount of glycogen stored up in the outer parts of 

 the liver cells is very considerable. 



Average Amount of Glycogen in the Liver of Dogs under various Diets (Pavy). 



Amount of 

 Diet. Glycogen in Liver. 



Animal food . 7 '19 per cent 



Animal food with sugar (about |-lb of sugar daily) . 14*5 ,, 



Vegetable diet (potatoes, with bread or barley-meal) . 17 '23 ,, 



The dependence of the formation of glycogen on the kind of food 

 taken is also well shown by the following results, obtained by the 

 same experimenter : 



Average Quantity of Glycogen found in the Liver of Rabbits after Fasting, and 

 after a Diet of Starch and Sugar respectively. 



Average amount of 

 Glycogen in Liver. 



After fasting for three days Practically absent 



diet of starch and grape-sugar . . . 15 '4 per cent 

 cane-sugar 16'9 ,, 



The diet most favourable to the production of a large amount of 

 glycogen is a mixed diet containing a large amount of carbohydrate, 

 but with some proteid. Fats taken in as food do not increase the 

 amount of glycogen in the cells. Glycerin injected into the ali- 

 mentary canal may increase the glycogen of the liver, probably 

 because it hinders the conversion of glycogen into sugar ; the 

 glycogen therefore is allowed to accumulate in the liver. 



Destination of G-lycogen. There are two chief theories as to the 

 destination of hepatic glycogen. (1.) That the glycogen is converted 

 into sugar during life by the agency of a ferment (liver diastase) also 

 formed in the liver ; and that the sugar is conveyed away by the 

 blood of the hepatic veins, to undergo combustion in the tissues. (2.) 

 That the conversion into sugar only occurs after death, and that 

 during life no sugar exists in healthy livers, glycogen not undergoing 

 this transformation. 



The first view is that of Claude Bernard, and has been adopted by 

 the majority of physiologists. The second view is that of Pavy: 

 he denies that the liver is a sugar-forming organ, he regards it as a 

 sugar-destroying organ; the sugar is stored as animal starch, but 

 never again leaves the liver as sugar during life. He has been unable 

 to find more sugar in the hepatic blood than in the portal blood. 

 Other observers have found an increase in the sugar of the blood 

 leaving the liver, but the estimation of sugar in a fluid rich in 

 proteids is a matter of great difficulty. Even if the increase is so 

 small as hardly to be detected, it must be remembered that the 

 whole blood of the body passes through the liver about twice a 

 minute, so that a very small increase each time would mount up to 

 a large total. 



