140 NUTRITIONAL PHYSIOLOGY 



to the "glycogenic function" of the liver, the fact that gly- 

 cogen is deposited also in the skeletal muscles was over- 

 looked. In these tissues it does not reach any such per- 

 centage as may be found in the liver, but inasmuch as the 

 muscles form nearly half the entire mass of the body, a 

 small percentage means a large aggregate. Collectively, 

 the muscles have commonly been estimated to hold an 

 amount equal to that in the liver, and there is a growing 

 impression that they contain even more. The total gly- 

 cogen in the system may probably be as much as 400 

 grams, or nearly a pound. The question which now calls 

 for consideration concerns the importance of maintaining 

 such a strict constancy in the sugar-content of the blood. 

 Some light is thrown on this matter when we observe 

 the result of artificial increase of sugar concentration. 

 This may be brought about by injecting sugar solution 

 into the blood-vessels. If this is done freely there is 

 excessive lymph-formation and other evidence of deranged 

 conditions in the circulatory system. A symptom to 

 which especial attention must be called is the appearance 

 of sugar in the urine under such circumstances. The 

 kidneys are so organized that any distinct rise of sugar in 

 the blood leads to the excretion of the excess. Thus the 

 composition of the blood is restored to the standard, while 

 potential food is lost to the tissues. Such a waste of sugar 

 is less likely to follow abundant feeding of foods rich in it 

 than to occur after the experimental procedure just de- 

 scribed, but it may nevertheless result from the selection 

 of peculiar diets. It is then called alimentary glycosuria. 

 This escape of surplus sugar is not to be confused with 

 diabetes. Alimentary glycosuria is induced somewhat 

 readily by eating sugar, but hardly ever by eating starch. 

 The differing reaction is presumably explained by the fact 

 that sugar requires a brief digestive treatment and is then 

 rapidly absorbed. Starch, on the other hand, has to pass 

 through serial stages of digestion,- and the absorption of 

 the resulting sugar is extended over a longer period. In 

 the first case we may suppose that the inrush of sugar over- 



