374 THE LIVER. 



frogs which had starved 13 months still contained remarkably large 

 amounts of glycogen due to this reformation (PFLUGER), makes the 

 formation of glycogen from protein very probable. 



If the question is raised as to the action of the various bodies on 

 the accumulation of glycogen in the liver, it must be recalled that a forma- 

 tion of glycogen takes place in this organ, as well as a consumption of the 

 same. An accumulation of glycogen may be caused by an increased 

 formation of glycogen, but also by a diminished consumption, or by both. 



It is not known how the various bodies above mentioned act in this 

 regard. Certain of them probably have a retarding action on the trans- 

 formation of glycogen in the liver, while others perhaps are more com- 

 bustible, and in this way protect the glycogen. Some probably excite 

 the liver-cells to a more active glycogen formation, while others yield 

 material from which the glycogen is formed, and are gly cog en-formers 

 in the strictest sense of the word. The knowledge of these last-mentioned 

 bodies is of the greatest importance in the question as to the origin of 

 glycogen in the animal body, and the chief interest attaches to the 

 question: To what extent are the two chief groups of food, the proteins 

 and carbohydrates, glycogen-formers? 



The great importance of the carbohydrates in the formation of glycogen 

 has given rise to the opinion that the glycogen in the liver is produced 

 from sugar by a synthesis in which water separates with the formation 

 of an anhydride (LUCHSINGER and others). This theory (anhydride 

 theory] has found opponents because it neither explains the forma- 

 tion of glycogen from such bodies as proteins, carbohydrates, gelatin, 

 and others, nor the circumstance that the glycogen is always the same, 

 independent of the properties of the carbohydrate introduced, whether 

 it is dextrogyrate or levogyrate. 1 This last circumstance does not now 

 present any special difficulty, since we know that the simple sugars can 

 easily be transformed into each other. It was formerly the opinion of 

 many investigators that all glycogen is formed from protein, and that 

 this splits into two parts, one containing nitrogen and the other being 

 free from nitrogen; the latter is the glycogen. According to these 

 views, the carbohydrates act only in that they spare the protein and 

 the glycogen produced therefrom (sparing theory of WEISS, WOLFFBERG, 

 and others 2 ) . 



In opposition to this theory C. and E. VOIT and their pupils have 

 shown that the carbohydrates are " true " glycogen-formers. After par- 

 taking of large quantities of carbohydrates, the amount of glycogen stored 

 up in the body is sometimes so great that it cannot be covered by the 



1 See Pfliiger in his Arch., 121. 



2 In regard to these two theories, see especially Wolffberg, Zeitschr. f . Biologic, 16. 



