716 FRANCIS H. McCRUDDEN 



determined the glucose content of the blood before and after the work 

 (Weiland(a)). There was a decrease in the glucose content of the blood 

 in every case; the average blood sugar before exercise was 0.090 per cent, 

 the average after exercise 0.065 per cent. The severe convulsions of 

 tetanus may require so much glucose as to result in a fall of blood sugar in 

 the general circulation to one-third the normal (Grote, Pnrjesz, Underhill 

 and Blatherwick). 



As the concentration of sugar in the blood falls, the muscular power 

 diminishes, but it can be restored by glucose (Furth and Schwarz). Shum- 

 berg has demonstrated that the injection of carbohydrates enables fatigued 

 muscle to contract more powerfully. This has been brought out in another 

 way by Lee and Harrold, who observed that the intense fatigue shown by 

 the muscles of the cat, whose blood sugar had been lowered by phlorizin 

 administration, is not observed in control animals whose body has been 

 flooded with sugar previous to the phlorizin administration. Hellsten has 

 reported in man an increased capacity for mechanical work in the morning, 

 before breakfast, twenty to forty minutes after ingesting sugar. 



The gradual destruction of glucose by contracting muscle, and the 

 p'ower of glucose to restore activity to the muscle which has become en- 

 feebled as a result of the disappearance of its store of glucose, has been 

 demonstrated especially convincingly in the case of heart muscle. The 

 heart may be isolated from the body, and, by perfusing with Ringer's solu- 

 tion, kept alive and contracting. As its store of glycogen becomes used up, 

 the heart will beat more and more feebly, until it finally stops beating alto- 

 gether. But if glucose is added to the pel-fusion fluid, this sugar is utilized 

 (Locke and Rosenheim(a) (&)) and the heart beats more powerfully and 

 for a longer time (Locke(a) (6) (c) ). The isolated dog's heart, for exam- 

 ple, uses up about 4 mgm. glucose per hour per gram heart muscle (Knowl- 

 ton and Starling). In the case of f ne rabbit, the amount used from 1.2 to 

 1.7 mgm. glucose per hour per gram of heart muscle about one-sixth per 

 cent per hour of the heart weight (Locke and Rosenheim(&) ). The utiliza- 

 tion of glucose by muscle is a complicated physiological process. If the 

 pancreas of the animal is extirpated before the heart is removed, the heart 

 loses its power to utilize glucose (Knowlton and Starling) ; but this power 

 can be restored by addition of pancreas extract to the perfusion fluid. This 

 property is inherent in glucose alone; other sugars are impotent (Locke 

 and Rosenheim(a)). 



In man the blood normally contains about one-tenth of one per cent 

 of glucose, the extremes in health and in disease in which the carbohydrate" 

 metabolism is not affected, being about 0.09 per cent and 0.12 per cent. 



Table 1 and Chart 1 show the figures obtained by Weston, and McCrud- 

 den and Sargent (&) in health and various diseases. .Other figures, differ- 

 ing only very slightly from these, are on record in the literature ; but these 

 investigators used the same technic which has been used in determining 



