374 THE MUSCLE-TISSUE. 



gether, when three days later the albuminous metabolism was dimin- 

 ished as much as possible by giving but little albumin, but furnish- 

 ing much fat. To a certain extent the fats may supply the energy, 

 however, which is necessary for the functioning of muscle-tissue 

 when a sufficient supply of glycogen is not available. 



Of the role which the pancreas plays in the sugar metabolism of 

 muscle-tissue mention has already been made. In the formation of 

 the glycogen and its inversion to glucose ferments are also no doubt 

 active. 



Isolation. If it is desired to isolate the glycogen from muscle- 

 tissue, it is necessary to place the material in boiling water imme- 

 diately after the death of the animal, so as to prevent its trans- 

 formation into glucose and the resulting products of decomposition. 

 Otherwise this will occur, as the death of the individual cells does 

 not coincide in point of time with the death of the animal as a 

 whole, and there is danger, moreover, that the inverting ferments 

 of the tissue remain active. That this actually occurs can be 

 readily demonstrated by treating one portion of the muscle-tissue as 

 described, while a second portion is allowed to remain exposed to 

 the air for a few hours. Both portions are then examined for 

 glycogen, when it will be seen that only the first gives a positive 

 reaction. (As regards the details of the method, see page 435.) 



Quantitative Estimation (according to Pfliiger). 100 grammes of 

 finely hashed, perfectly fresh muscle-tissue and 100 c.c. of a 60 

 per cent, solution of potassium hydrate (Merck la) are shaken in a 

 200 c.c. flask, so that the meat is evenly distributed. The mixture 

 is heated for two hours on a boiling water-bath, then transferred 

 to a 400 c.c. flask, diluted to the 400 c.c. mark, and filtered through 

 glass wool. The filtrate should be clear or but faintly opalescent. 



A carefully measured portion of 100 c.c. of the filtrate is treated 

 with an equal quantity of 96 per cent, alcohol. After standing for 

 twenty-four hours the precipitate is collected on a 15 c.c. filter 

 (Swedish MunktelPs), first washed with a mixture of 1 volume of 

 15 per cent, potassium hydrate solution and 2 volumes of 96 per 

 cent, alcohol and then with the alcohol alone. It is now dissolved 

 in water, the solution accurately neutralized with hydrochloric 

 acid, transferred to a 500 c.c. flask, treated with 25 c.c. of hydro- 

 chloric acid (specific gravity 1.19) and almost diluted to the mark. 

 Should the amount of glycogen be very small, as much as 300 c.c. 

 of the original filtrate must be used. The flask is closed and 

 heated for three hours on a boiling water-bath. Water is then 

 added to the 500 c.c. mark and the sugar estimated according to 

 the method which Pfliiger describes. For a consideration of this 

 method the reader is referred to the original (Pfluger's Arch., 1902, 

 vol. 93, p. 163). 



