370 THE LIVER. 



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

 adrenalin. 



Glycogen forms an amorphous, white, tasteless, and inodorous 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). Its aqueous solution is dextrorotatory, and HUPPERT 

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

 the same result by using a perfectly pure solution of glycogen. 1 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 ammoniacal 

 basic lead acetate. An aqueous solution of glycogen made alkaline 

 with caustic potash (15 per cent KOH) is completely precipitated by 

 an equal volume of 96-per cent alcohol. Tannic acid also precipitates 

 glycogen. It gives a white granular precipitate of benzoyl-glycogen 

 with benzoyl chloride and caustic soda. Glycogen is completely pre- 

 cipitated by saturating its solution at ordinary temperatures with 

 magnesium or ammonium sulphate. s lt is not precipitated by sodium 

 chloride, or by half saturation with ammonium sulphate (NASSE, NEU- 

 MEISTER, HALLIBURTON, YOUNG 2 ). On boiling with dilute caustic 

 potash (1-2 per cent) the glycogen may be more or less changed, especially 

 if it has been previously exposed to the action of acid or to BRUCKE'S 

 reagent (see below) (PFLUGER). On boiling with stronger caustic potash 

 (even of 36-per cent) it is not injured (PFLUGER). By diastatic enzymes 

 glycogen is converted into maltose or dextrose, depending upon the nature 

 of the enzyme. It is transformed into dextrose by dilute mineral acids. 

 According to TEBB 3 various dextrins appear as intermediary steps in 

 the saccharification of glycogen, depending on whether the hydrolysis 

 is caused by mineral acids or enzymes. The question whether the gly- 

 cogen from various animals and different organs is the same in this regard 

 has not been sufficiently investigated. Nor has it been decided whether 



1 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. 



2 Young, Journ. of Physiol., 22, citing the other investigators. 



3 Journ. of Physiol., 22. 



