224 GLYCOGEN 



Relation Between the Consumption of Sugar by the 

 Muscles and the Disappearance of Glycogen of the Liver. It 

 is commonly accepted that glycogen is one of the generally 

 distributed tissue constituents. Its distribution in the econ- 

 omy is, however, by no means uniform, by far the greatest 

 proportions being accumulated in muscle and the liver. The 

 extent of its accretion in these latter structures is illustrated 

 by the fact that in a frog's liver glycogen may actually con- 

 stitute more than half of the dried substance. 11 In view of 

 the unquestioned importance of sugar as a source of mus- 

 cular power it may be appreciated why the living body 

 should generally show a more constant fixation of muscle 

 glycogen than of liver glycogen; and among the different 

 muscles why the heart should give up its glycogen least 

 readily. By long-continued strychnine convulsions, which 

 is one of the most effective means of inducing the body to 

 use up its supply of glycogen, P. Jensen ultimately suc- 

 ceeded in getting the frog's heart free of glycogen and show- 

 ing that even then it is capable of continuing its activity. As 

 long as the body has a carbohydrate supply at its disposal, 

 however, the functionating muscles are sure to find some 

 means and some way to obtain it; but how they actually 

 accomplish this is, it must be confessed, at present unknown. 

 There has been a hypothesis that in muscular contraction the 

 intramuscular nerve-endings are stimulated and transmit, 

 as it were, telegraphic information to the great central sup- 

 ply office in the liver to provide additional fresh nutrient 

 material ; but as a matter of fact no one has proved such 

 relationship. It is quite possible that nervous telegraphic 

 lines have nothing whatever to do with notifying the liver 

 and other organs that assistance is needed for the muscles. 

 It may very well be that the circulating blood enacts this 

 role of messenger automatically when its level of sugar is 

 lowered. There is no doubt that in a general way the 



11 M. Bleibtreu, Mitt. a. d. Naturwiss. Vereinigung fiir Neuostpommern 

 und Riigen, 1907, cited in Centralbl. f. Physiol., 22, 448, 1908. 



