GLYCOGEN. 391 



shark, whose liver is very rich in fat, even though well nourished, only 

 has comparatively low values for the glycogen in the liver, 9.3-23.8 

 p. m. (BOTTAZZI l ). According to CREMER the quantity of glycogen in 

 plants (yeast-cells) is, as in animals, dependent upon the food. He 

 finds that the yeast-cells contain glycogen, which disappears from the 

 cells in the auto-fermentation of the yeast, but reappears on the intro- 

 duction of the cells into a sugar solution. 



The quantity of glycogen of the liver (and also of the muscles) is 

 also dependent upon rest and activity, because during rest, as in hiberna- 

 tion, it increases, and during work it diminishes. KULZ has shown that 

 by hard work the quantity of glycogen in the liver (of dogs) is reduced 

 to a minimum in a few hours. The muscle-glycogen does not diminish 

 to the same extent as the liver-glycogen. KULZ, ZUNTZ and VOGELIUS, 

 FRENTZEL, and others have been able to render rabbits and frogs nearly 

 glycogen-free by suitable strychnine poisoning. The same result is pro- 

 duced by starvation followed by hard work. According to GATIN- 

 GRUZEWSKA, 2 the liver and muscles in rabbits can be made glycogen- 

 free after 36-40 hours by first starving one day and then injecting 

 adrenalin. 



Glycogen forms an amorphous, white, tasteless, and non-odorous powder. 

 When perfectly pure, and by proper alcohol precipitation, it can be obtained 

 as rods or prisms which look like crystals (GATIN-GRUZEWSKA) . It 

 gives an opalescent solution with water which, when allowed to evaporate 

 on the water-bath, forms a pellicle over the surface that disappears again 

 on cooling. It is undecided whether we here have a true solution or 

 not. Like other colloids, glycogen in water under the influence of the 

 electric current migrates to the anode, on which it collects (GATIN- 

 GRUZEWSKA). According to BoiTAZZi, 3 who obtained the same results, 

 a little acid or a little alkali modify the results so that the glycogen becomes 

 isoelectric. Its aqueous solution is dextrorotatory, and HUPPERT found 

 it to be (:) D = +196.63 . GATIN-GRUZEWSKA has recently obtained 

 the same result by using a perfectly pure solution of glycogen. A 

 solution of glycogen, especially on the addition of NaCl, is colored wine- 

 red by iodine. It may hold cupric hydroxide in solution in alkaline 

 liquids, but does not reduce it. A solution of glycogen in water is not 

 precipitated by potassium-mercuric iodide and hydrochloric acid, but is 

 precipitated by alcohol (on the addition of NaCl when necessary), or 



1 Arch. Ital. d. Biol., 48; cited in Bioch. Centralbl., 7, 833. 



2 Compt. Rend., 142. 



3 Bottazzi, Chem. Centralbl. 1909 p. 1423; Bottazzi and d'Errico (Pfliiger's Arch., 

 115) have investigated the viscosity, the electrical conductivity and the freezing-point 

 of glycogen solutions at different concentrations. 



