.CARBOHYDRATES. 71 



store of glycogen, namely liver-glycogen, and the consumption of carbo- 

 hydrates by the muscles. According to all our experience up to the 

 present time, glycogen is not directly oxidized, but is previously decom- 

 posed into d-glucose. This is shown directly by the experiments of J. 

 Ranke 1 and of Otto Nasse. 2 The former examined the sugar content of 

 the hind legs of a number of frogs, one leg being tetanized and the 

 other at rest. Several determinations showed 0.058 per cent sugar in 

 the dry substance of the resting muscle, and 0.082 per cent in the tetanized 

 muscle. The sugar content, therefore, was increased 41 per cent in the 

 latter case. The hydrolysis of glycogen is evidently caused, as Magendie 3 

 has shown, by a ferment which in its action coincides with that of diastase, 

 which is already known to us. In the liver also the stores of glycogen are 

 decomposed in this way. 4 Here, besides d-glucose, the intermediate products 

 dextrin and maltose have been detected. They are probably formed in 

 the breaking down of glycogen in the muscles, but their presence has never 

 been established with certainty. The fact that the hydrolysis of glycogen 

 in the liver is not to be considered as a result of the activity of the cells, 

 but rather that it is due to a ferment which can be separated from the 

 liver cells, was clearly shown as long ago as 1873 by von Wittich. 5 He 

 proved that it was possible to extract by means of glycerol from liver 

 which was completely freed from blood and hardened by alcohol a fer- 

 ment which was capable of hydrolyzing glycogen. von Wittich showed 

 that this ferment belonged to the liver cells rather than to the blood by 

 again and again obtaining the diastatic ferment after repeated, thorough 

 washings of the liver. It is also possible, as Pavy has shown, to treat 

 liver with alcohol, dry it, and preserve it indefinitely. If such a preparation 

 is digested with water, the diastatic reaction will be obtained invariably. 

 On the other hand, the objection may be raised to this line of reasoning, 

 that the formation of sugar is perhaps due to the action of micro-organisms, 

 an assumption which in the light of recent experience obtained by working 

 with organs and their extracts does not seem improbable. 6 E. Salkowski, 7 



1 Tetanus, p. 168, Leipsic, 1865. 



2 Pfliiger's Arch. 2, 97 (1869). 



3 Compt. rend. 23, 189 (1846). 



4 Musculus and v. Mering: Z. physiol. Chem. 2, 416 (1878-79). E. W. Pavy: The 

 Physiology of Carbohydrates, London, 1894. Kiilz and Vogel: Z. Biol. 31, 108 (1895). 



5 Pfliiger's Arch. 7, 28 (1873). 



* For an explanation of the other view, that the sugar formation from glycogen is 

 caused by the life process of the liver cells, see M. Foster: Text-book of Physiology, 

 appendix by Sheridan Lea, pp. 58, 98. Noel Paton: Hepatic Glycogenesis, Trans. Roy. 

 Soc. 1894, and Phil. Trans. 185 B, 233 (1894). 



7 Deut. Med. Wochschr. No. 16, 1888; Arch. Physiol. 554 (1890); Zent. med. Wis- 

 sensch. Jg. 27, No. 13, 227 (1889). See also Otto Nasse: Rostocker Ztg. No. 105 (1889). 

 Salkowski: Z. Win. Med. p. 90 (1891), and Pfliiger's Arch. 56, 339 and 351 (1894). 

 Arthus and Huber: Arch, de Physiol. 651 (1892). 



