230 GLYCOGEN 



doses over a longer period of time, the serum would take on 

 inverting properties. This is evidently nothing more than 

 an exaggeration of a property which is already normally 

 possessed, perhaps in analogy to the phenomena noted in 

 the observations of Abderhalden already mentioned (vide 

 sup., p. 218). The same thing is indicated by the studies of 

 Hohlweg and Voit, 27 who noted almost complete elimination 

 after subcutaneous injection of twenty grams of cane-sugar 

 into normal rabbits; while in animals with their metabolic 

 processes increased by overheating a loss of about twenty 

 per cent, was obtained. 



That polysaccharides like starch and inulin, which under- 

 go cleavage into glucose or Isevulose in the intestine, con- 

 tribute to glycogen formation is self-explanatory. As re- 

 sorption of these substances can take place only after com- 

 plete cleavage has occurred, large amounts may be ingested 

 by human beings without necessarily inducing excessive 

 presence of sugar in the system and without consequent 

 alimentary glycosuria. 



Other Substances of the Sugar Series. Statements as to 

 the glycogen forming properties of the pentoses are more or 

 less confusing 28 ; off-hand it must be regarded as very 

 questionable whether they possess such properties. Con- 

 version of the pentoses into glycogen, as a matter of fact, 

 would be possible only in a very round-about way (decompo- 

 sition into molecular groups with two or three carbon 

 atoms). 



It is rather singular that glucosamine cannot be classed 

 among the glycogen producers when one thinks how close it 

 stands to grape-sugar stereochemically 29 ; the body is evi- 



H. Hohlweg and F. Voit (Giessen), Zeitschr. f. Biol., 51, 491, 1908. 



28 M. Cremer, Salkowski, Frentzel, Neuberg and Wohlgemuth ; cf. critical 

 review of the Literature; M. Cremer, Ergebn. d. Physiol., 1' 898-899, 1902; 

 cf. also L. B. Stookey and A. H. Jones, Proc. Soc. Exper. Biol., 5, 123; cited 

 in Jahresber. f. Tierchem., 38, 446, 1908. 



29 Fabian, S. Frankel and Offer, Cathcart, Bial, Forschbach, K. Meyer, 

 Hofmeister's Beitr., 9, 134, 1907; F. Rogozinski, C. R,., 153, 211, 1911. 



