FORMATION OF GLYCOGEN. 375 



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 gly cog en-formers. For the present, only 

 dextrose, levulose, galactose (WEINLAND *), and perhaps also d-mannose 

 (CREMER) are designated as true glycogen-formers. Other mono- 

 saccharides may indeed, according to CREMER influence the formation 

 of glycogen, but they are not converted into glycogen, and hence are 

 called only pseudogly cog en-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 

 be inverted in the intestine. These two varieties -of sugar, therefore, 

 cannot, like dextrose and levulose, serve as glycogen-formers after sub- 

 cutaneous injection, but reappear almost entirely in the urine (DASTRE, 

 FR. VOIT) . Maltose, which is inverted by an enzyme present in the blood, 

 passes only to a slight extent into the urine (DASTRE and BOURQUELOT 

 and others), and it can, like the monosaccharides. even after subcuta- 

 neous injection, be used in the formation of glycogen (FR. VoiT 2 ). 



The ability of the liver to form glycogen from monosaccharides has 

 also recently been shown by K. GRUBE 3 in a very interesting and direct 

 manner, by perfusion experiments with solutions of various carbohydrates. 

 In these perfusion experiments on tortoise livers, dextrose produced an 

 abundant glycogen formation, while with levulose and galactose it was 

 less abundant. Pentoses, disaccharides, casein and amino-acids (glycocoll, 

 alanine and leucine) were inactive while on the contrary glycerin and 

 also formaldehyde acted as glycogen-formers. 



After PAVY 4 first showed the occurrence of carbohydrate groups in 

 ovalbumin, other investigators were able to split off glucosamine from 

 this and other protein substances (see Chapter III), and the question 

 arose whether the amino-sugar could serve in the formation of glycogen. 

 The investigations carried out in this direction by FABIAN, FRANKEL 

 and OFFER, CATHCART and BIAL, have shown that the glucosamine 

 introduced into the organism is in part eliminated unchanged in the 

 urine and has no glycogen-forming action. No definite conclusions 



1 E. Voit, Zeitschr. f. Biologie, 25, 543, and C. Voit, ibid., 28. See also Kausch 

 and'So.cin, Arch. f. exp. Path. u. Pharm., 31; Weinland, Zeitschr. f. Biologie, 40 and 

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



" 2 Dastre, Arch, de Physiol. (5), 3, 1891; Dastre and Bourquelot, Compt. rend., 98; 

 Fritz Voit, Verhandl. d. Gesellsch. f. Morph. u. Physiol. in Munchen, 1896, and Deutsch. 

 Arch. f. klin. Med., 58. 



3 Pfluger's Arch., 118, 121, 122 and 126. 



4 The Physiology of the Carbohydrates, London, 1894, 



