CARBOHYDRATES AND FATS. 913 



is probable that these bodies represent intermediary products 

 in the metabolism of the fats of the body which escape oxidation. 

 The large accumulation of these acid bodies in the blood and tissues 

 of the diabetic is responsible for the production of the serious con- 

 dition of acidosis shown by those suffering from severe forms of 

 this disease. There is no wholly satisfactory explanation of the 

 relationship between the loss of power to metabohze the sugar and 

 this accompanying incompleteness in the normal processes of oxi- 

 dation of the fat. 



Phlorhizin Diabetes. — Phlorhizin is a vegetable glucoside ob- 

 tained from the roots of certain trees — e. g., apple, pear. When 

 injected into an animal it causes a glycosuria which is temporary, 

 but which may be renewed by repeated injections. Examination 

 of the blood in this case reveals the fact that the percentage of 

 sugar is not increased, so that the immediate cause of the glycosuria 

 is different from that responsible for the diabetes of man or of 

 animals without the pancreas. Sugar given to a phlorhinized 

 animal is all excreted in the urine, and the same is true of the sugar 

 formed in the body from protein, so that the interference with sugar 

 metabolism is complete as long as the action of the drug continues. 

 A satisfactory explanation of the action of the phlorhizin has not 

 yet been obtained, but it would seem that the drug acts primarily 

 in some way upon the kidney itself. It has been suggested (Stiles 

 and Lusk*) that the sugar exists in part in the blood in a colloidal 

 combination and that under the influence of the phlorhizin this 

 combination is broken up in the kidney and the sugar is liberated 

 in a form in which it is easily excreted. Experimental work, how- 

 ever, has failed to confirm this hypothesis, f 



From this brief description of the fate of the carbohydrate 

 in the body it is evident that its history as a' food-stuff might 

 be considered conveniently under three heads, namely, its supply, 

 its storage, and its consumption. The supply is regulated by the 

 diet. In the usual diet carbohydrate constitutes the chief and 

 also the most variable factor. Its cheapness, its ease of digestion 

 and of consumption make it the most convenient and economical 

 source of energy to the body. When our energy needs are large, 

 as in muscular work, the carl^ohydrate portion of the diet is 

 increased; when the energy needs are small, as in a sedentary 

 life, the amount of carbohydrate is reduced. The storage of 

 carbohydrate in the body is provided for temporarily by the 

 glycogenetic function of the liver and the muscles. This function 

 may be deranged for a time by injuries to the central nervous 



* Stiles and Lusk, "American Journal of Physiology," 10, 67, 1903. 

 t See Hess and McGuigan," Journal of Pharmacology and Exp. Thera- 

 peutics," 6, 45, 1914. 

 58 



