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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 J
). According to Cbemeb 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. Iyulz 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, Ztjntz 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 Bottazzi,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 Htjppert found
it to be (tt) D = +196.63°. Gatin-Grtjzewska 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. 1009 p. 1423; Bottazzi and d’Errico (Pfluger’s Arch.,
115) have investigated the viscosity, the electrical conductivity and the freezing-point
of glycogen solutions at different concentrations.
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