138 PHYSIOLOGICAL CHEMISTRY. 



Glycogen and the Glycogen Formation. 



Glycogen was discovered in 1857 by BERNARD and HENSEN in- 

 dependently of each other. It is a carbohydrate closely related to the 

 starches or dextrins with the general formula C 6 H 10 5 , perhaps 

 6(C 6 H 10 6 ) + H 2 (KuLZ and BOENTEAGEE). The largest quanti- 

 ties are found in the liver of full-grown animals (BERNARD, HEN- 

 SEN, and others), and smaller quantities in the muscles (NASSE, 

 BRUCKE, and others). It is found in very small quantities in many 

 organs, such as the lungs, skin, the sheath of the roots of the hair 

 (WIERSMA, BARFUTH), the middle coat of the arteries, and also in 

 certain epithelial cells (SCHIELE, WIERSMA). Its occurrence in 

 lymphoid cells and in pus has been mentioned in the previous 

 chapter. Glycogen has been shown by BERNARD and KUHNE to be 

 very widely diffused in the embryonic tissue, and it seems habitually 

 to be a constituent of tissues in which a rapid cell-formation and 

 cell-development is taking place (HOPPE-SEYLER). It is also 

 present in rapidly-formed pathological swellings (HOPPE-SEYLER). 

 It has been found in several organs in diabetes mellitus. Glycogen 

 is also found in the plant kingdom in the myxomycetae. 



The quantity of glycogen in the liver, as also in the muscles, de- 

 pends essentially upon the food. In starvation it disappears after 

 a short time, but more rapidly in small than in large animals. Ac- 

 cording to the old views (LUCHSINGER), it disappears earlier from 

 the muscles than from the liver; but according to more modern 

 views (ALDEHOFF), the reverse of this takes place. After partaking 

 of food especially rich in carbohydrates, the liver becomes rich 

 again in glycogen, the greatest increment occurring 14 to 16 hours 

 after eating (KuLz). The quantity of glycogen in the liver may 

 be 100-120 p. in. or indeed even more after the consumption of 

 food rich in carbohydrates. Ordinarily it is considerably less or 

 12-30 to 40 p. m. 



Glycogen forms an amorphous, white, tasteless, and inodorous 

 powder. It gives an opalescent solution with water which, when al- 

 lowed to evaporate in the water-bath, forms a pellicle over the surface 

 that disappears again on cooling. The solution is dextro-gyrate, 

 (a] D = -{- 211 (KuLz). The specific rotary power is given some- 

 what differently by various investigators. A solution of glycogen 



