CARBOHYDRATES. 75 



with the combustion of carbohydrates in the muscle, but results from the 

 breaking down of protein. We shall see later on that alanine, which 

 is formed by the hydrolysis of albumin, stands in close relation to lactic 

 acid. 1 



The role of the carbohydrates in the animal organism is by no means 

 limited to the production of muscular energy. Above all they are to be 

 considered as a source of heat. Thus it is possible to cause the glycogen 

 stores to disappear by merely chilling the animal. 2 The carbohydrates, 

 without doubt, take an active part in the life process of the individual 

 cells. They take part also in their building up. At present we know 

 nothing concerning the way they occur in the organism and concerning 

 their union in the cell complex. We have already mentioned the occur- 

 rence of pentoses, especially xylose, which is in the nucleoproteids. We 

 shall later on see that there are indications of the hexoses also being used 

 as building material for the nuclei of the cells. 



1 Cf. Astaschewsky: Z. physiol. Chem. 4, 397 (1880). Warren: Pfliiger's Arch. 24, 

 391 (1881). Heffter: Arch, exper. Path. Pharm. 31, 225 (1893). Werther: Pfliiger's 

 Arch. 46, 63 (1890). Spiro: Z. physiol. Chem. 1, 111 (1877-78). Zillesen: Z. physiol. 

 Chem. 15, 387 (1891). Araki: Z. physiol. Chem. 15, 335 and 546 (1891), and Z. 

 physiol. Chem. 16, 453 (1892). Hoppe-Seyler: Z. physiol. Chem. 19, 476 (1894). 



a E. Kiilz: Pflijger's Arch. 24, 14 (1881). 



