X. 



QUANTITATIVE DETERMINATION OF GLYCOGEN. 1 



Place 100 g. of the ground meat or organ and 100 cc. of 

 60 per cent, potassium hydroxide solution in a 200-cc. flask. 

 Use the purest potassium hydroxide made by "Merck." 

 The strength of the potassium hydroxide solution is deter- 

 mined accurately with standard hydrochloric acid. 



Before placing the flask in the boiling water-bath shake 

 it once or twice in order to mix the contents thoroughly, and 

 repeat the shaking after the flask has been heated one- 

 quarter to one-half of an ho\ir. As soon as the liquid has 

 assumed the temperature of the boiling water-bath and no 

 further expansion takes place, close the flask with a rubber 

 stopper. 



After heating for two hours, take the flask out of the boil- 

 ing water-bath, empty it into a 400-cc. measuring-flask, and 

 rinse it out with boiling water. When the liquid is cold fill 

 the 400-cc. flask up to the mark with sterilized water and 

 filter the solution through glass wool until the filtrate is quite 

 clear or only slightly opalescent. From a burette measure 

 off 100 cc. of the filtered meat solution into a 300-cc. beaker, 

 add 100 cc. of 96 per cent. (Tralles) alcohol, and mix thor- 

 oughly with a glass rod. The precipitate of glycogen settles 

 very rapidly, so that it may be filtered off even after a quarter 

 of an hour. It is safer, however, to wait some hours or, 



J Pfliiger in Pfliiger's Arch. 93, 163. 



244 



