SOURCE OF GLYCOGEN 469 



AVERAGE AMOUNT OF GLYCOGEN IN THE LIVER OF DOGS UNDER VARIOUS 



DIETS. (PAVY.) 



Diet. Amount of glycogen in the liver. 



Flesh food 7.19 per cent. 



Flesh food with sugar 14.5 per cent. 



Vegetable diet, i.e., potatoes with bread or barley meal. 17 . 23 per cent. 



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

 is also 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. 



After three days' fasting Practically absent. 



After diet of starch and grape sugar * 5 4 per cent. 



After diet of cane sugar 16.9 per cent. 



Glycerol injected into the alimentary canal may increase the glycogen 

 of the liver. Observations indicate that glycogen may be formed in the 

 turtle liver when perfused with very dilute formaldehyde solutions. The 

 diet most favorable to the production of a large amount of glycogen is a 

 mixed diet containing a large amount of carbohydrate, but with some 

 protein. Glycogen is stored in other organs of the body. Of these the 

 muscles are deserving of special mention. The amount of glycogen in the 

 muscles of young animals is often considerable. The placenta is also a 

 storehouse of glycogen. 



Glycogenesis Controlled by Hormone. Glycogenesis and its storage 

 is strictly dependent on chemical control. In disease of the pancreas 

 leading to its degeneration, or in surgical removal of the pancreas the 

 liver is unable to store glycogen. Even when the blood is rich in sugar 

 to the level at which its excretion into the urine occurs, no storage of 

 glycogen occurs. The body seems quite unable to metabolize sugar or to 

 convert it into glycogen as in the normal. From such observations 

 physiologists have long coupled glycogenesis with the function of the 

 pancreas. This association depends upon an internal secretion of the 

 islands of Langerhans. Extracts of pancreas have from time to time been 

 experimentally prepared that seemed to lower the amount of sugar lost 

 during glycosuria. Such preparations have peculiar general toxicity 

 and little progress has resulted in explanation of the mechanism of sugar 

 control. 



However, Banting and Best have very recently, 1922, announced 

 brilliant results in the solution of this problem. They demonstrated that 

 intravenous injections of a watery extract of pancreas in which the 

 parenchyma had been degenerated by previous operative procedure, see 

 discussion of internal secreting glands, when injected into the circulation 

 of a depancreatized dog quickly lead to the disappearance of the excess 



