THE POLYSACCHARIDES. 15 
liver and muscle, 1 in embryonic tissues generally, 2 and in the bodies of 
molluscs. 3 It has been described in pathological growths, 4 and in 
the vegetable kingdom in many fungi 5 (truffles, mucor, yeast, 
myxomycetes). 
It may be dissolved out with boiling water (Briicke), 6 2 per cent, 
potash (Kiilz), 7 or by trichloracetic acid, 8 from the tissues in which it 
occurs. The extraction with this acid is, however, incomplete, and the 
product is impure. 9 Huizinga 10 recommends that glycogen should be 
extracted from the liver by a mixture of equal parts of saturated 
solution of mercuric chloride, and Esktch's reagent (10 grms. of picric 
and 20 of citric acid in a litre of water). From this solution, 
which is proteid free, glycogen is precipitable hy alcohol. 
The pure material is a white tasteless powder, soluble in water, forming 
a strongly opalescent solution. It is insoluble in alcohol and in ether. 
It is strongly dextrorotatory ; u («) D = + 190 '-63. With Trommer's test 
it gives a blue solution, but no reduction occurs on boiling. 
With iodine it gives a port-wine red colour, which easily distin- 
guishes it from starch. Its precipitability by basic lead acetate dis- 
tinguishes it from dextrin. 
Prolonged boiling with water or boiling with dilute mineral acids 
converts it into sugar. The diastatic ferments act similarly. 
Max Cremer vl investigated the action of dilute acids on glycogen ; he 
found glucose and isomaltose (identified by their osazones), but no maltose. 
Kiilz and Yogel Vi investigated the action of diastatic ferments ; parotid saliva 
produced isomaltose and maltose in the proportion of 1 to 2 from liver-glycogen, 
and isomaltose with small amounts of maltose and dextrose from muscle- 
glycogen ; pancreatic juice and malt diastase produced practically the same 
result. The ferment in the liver which acts on glycogen produces dextrose. 
The physiological relationships of glycogen will be treated elsewhere. 
There is much controversy on the subject of the origin and fate of glycogen. 
There is, however, little doubt that it is chiefly a storage product from the 
carbohydrates of the food, 14 and that after death it is transformed into dextrose ; 
the principal controversies of recent years have centred round the question 
whether glycogen normally leaves the liver in the hepatic blood as sugar (as 
1 Claude Bernard, Corrupt, rend. Acad. d. sc, Paris, 1857, tome xliv. pp. 57S and 1325 ; 
xlviii. pp. 77, 683, 763 and 781; Hensen, Virchovfs Archiv, 1857, Bd. xi. S. 395; 0. 
Nasse, Arch. f. d. </es. Physiol., Bonn, 1869, Bd. ii. S. 97. 
2 Claude Bernard, " Physiologie exper.," 1855, tome i. p. 241 ; iv. p. 11 ; Salomon, 
Centralbl. f. d. mcd. Wissensch., Berlin, 1874, S. 738; Moriggia, ibid., 1875, S. 186 ; v. 
Wittich, Hermann's " Handbuch," 1883. 
3 Bizio, Ztschr. f. C'hem., Leipzig, 1866, S. 222 ; Bernard, " Lecons sur les phenomenes 
de la vie," 1879, tome ii. ; Krukenberg, " A r ergl. pbysiol. Studien," 1S80, Bd. ii. S. 52. 
4 Kiihne, Virchows Archiv, Bd. xxxii. S. 536 ; Sotnitschew.-ki, Ztschr. f. physiol. 
Chem., Strassburg, 1880, Bd. iv. S. 220. 
5 Kiihne, " Lehrbuch der physiol. Chem.," 1868, S. 334; Reinke and Rodewald, 
"Studien ueber das Protoplasma," Berlin, 1881, S. 34, 54, and 169; Errera, Bull. Acad, 
roy. de med. de Bdg., Bruxelles, Bd. iv. S. 451. 
6 Sitsungsb. d. k. Akad. d. Wissensch., Wien, 1871, Bd. lxiii. S. 214. 
7 Ztschr. f. Biol., Miinchen, 1886, Bd. iv. S. 191. 
8 Frankcl, Arch. f. d. ges. Phi/siol., Bonn, Bde. lii. S. 125 ; lv. S. 378. 
y Weidenbaum, ibid., Bde. liv. S. 319 ; lv. S. 380. 
10 Arch. f. d. ges. Physiol., Bonn, Bd. lxi. 
11 Huppert, Ztschr. f. 'physiol. Chem., Strassburg, Bd. xviii. S. 137. 
12 Ztschr. f. Biol., Miinchen, 1894, Bd. xxxi. S. 181. 13 Ibid., S. 108. 
14 According to Voit and his pupils {Ztschr. f. Biol., Miinchen, Bd. xxviii. S. 245), the 
liver forms glycogen only from dextrose and levulose, or from those carbohydrates which 
are converted into these smrars before thev reach the liver. 
