FORMATION OF GLYCOGEN. 395 



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 gly- 

 cogen has given rise to the opinion that the glycogen in the liver is pro- 

 duced from sugar by a synthesis in which water separates with the for- 

 mation of an anhydride (LUCHSINGER and others). This theory (anhy- 

 dride 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. 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 J ). 



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 

 proteins decomposed during the same time, and in these cases a gly- 

 cogen formation from the carbohydrates must be admitted. According 

 to CREMER only the fermentable sugars of the six carbon series or their 

 di- and polysaccharides are true glycogen-formers. For the present, only 

 glucose, fructose, and to a much less degree galactose (WEINLAND 2 ), 

 and perhaps also d-mannose (CREMER) are designated as true glycogen- 

 formers. Other monosaccharides may indeed, according to CREMER, 

 influence the formation of glycogen, but they are not converted into 

 glycogen, and hence are called only pseudoglycogen-formers. 



The poly- and disaccharides may, after a cleavage into the cor- 

 responding fermentable monosaccharides, serve as glycogen-formers. 

 This is true for at least cane-sugar and milk-sugar, which must first 



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



2 E. Voit, Zeitschr. f. Biologic, 25, 543, and C. Voit, ibid., 28. See also Kausch 

 and Socin, Arch. f. exp. Path. u. Pharm., 31; Weinland, Zeitschr. f. Biologic, 40 and 

 38; Cremer, ibid., 42, and Ergebnisse der PhysioL, 1. 



