METABOLISM, NUTRITION AND DIETETICS 451 



curara, the production of carbon dioxide falls much below 

 that of an intact animal at rest ; and the carbon given off by 

 such an animal on its ordinary vegetable diet can be shown, 

 by a comparison of the chemical composition of the food 

 and the excreta, to come largely from carbo-hydrates. 

 But, considering the relatively feeble metabolism of muscles 

 and glands when not functionally excited, the large volume 

 of blood which passes through them, the difficulty of deter- 

 mining small differences in the proportion of sugar in such 

 a liquid, the possibility that even in the blood itself sugar 

 may be destroyed, or that it may pass from the blood, with- 

 out being oxidized, into the lymph, too much weight may 

 easily be given to the results of direct analysis of the 

 in-coming and out-going blood. And although the recent 

 results of Chauveau and Kaufmann, obtained in this way, fit 

 in fairly well with what we have already learnt by less 

 direct, but more trustworthy, methods, they cannot be 

 accepted as yielding exact quantitative information. They 

 found that in one of the muscles of the upper lip of the 

 horse the quantity of grape-sugar used up during activity 

 (feeding movements) was 3*5 times as much as in the same 

 muscle at rest, and this corresponded with the deficit of 

 oxygen in the blood entering the muscle, and with the excess 

 of carbon dioxide in the blood leaving it. More dextrose 

 was also destroyed in the active than in the passive parotid 

 gland of the horse, but the excess per unit of weight of the 

 organ was far less than in muscle. 



Diabetes. In the disease known as diabetes mellitus, sugar 

 accumulates in the blood, and is discharged by the kidneys, 

 and it has been supposed that a derangement in the gly- 

 cogenic function of the liver is the cause of this accumula- 

 tion and of this discharge. An artificial and temporary 

 diabetes, in which the sugar in the urine undoubtedly arises 

 from the hepatic glycogen, can, indeed, be caused by punc- 

 turing the medulla oblongata in a rabbit at or near the 

 region of the vaso-motor centre. If the animal has been 

 previously fed with a diet rich in carbo-hydrates that is, 

 if it has been put under conditions in which the liver con- 

 tains much glycogen the quantity of sugar excreted by the 



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