THE METABOLISM OF CARBOHYDRATES 847 



The evidence that the carbohydrates play a necessary part in the meta- 

 bolic history of fats has already been mentioned (v. p. 836). We have seen 

 that in the absence of carbohydrates the last stages in the oxidation of fats 

 make default, so that the partially oxidised fatty acids, oxybutyric acid and 

 aceto-acetic acid, accumulate in large quantities and are excreted as such or 

 as acetone in the urine. Not only does this involve a loss of energy to the 

 body, but these organic acids require other bases for their neutralisation. 

 Up to a certain point they will be excreted in the urine in combination with 

 the fixed alkalies. When these are no longer present in sufficient quantity, 

 the acids will be excreted in combination with ammonia, so that the ammonia 

 of the urine is largely increased. If the condition of carbohydrate starvation 



>be continued, this mechanism of neutralisation is insufficient. and the pheno- 

 mena of acidosis dyspnoea and coma ensue, resulting in the death of the 

 animal. 

 Another effect of continued administration of phloridzin is fat infiltration 

 of the liver. This is merely a result of the carbohydrate starvation. A 

 similar condition of fat infiltration can be brought about by feeding with 

 pure protein plits fat. The liver seems to be able to act as a storehouse 

 either of fat or of carbohydrate, so that there is an inverse ratio between 

 the amount of glycogen and the amount of fat stored up in the liver at 

 any given time. It has been shown that the fat in the liver under these 

 circumstances is simply fat which has been transferred to this organ from 

 the ordinary fat depots, subcutaneous tissues, etc., of the body. 



(4) PANCREATIC DIABETES. Von Mering and Minkowski found that 

 total excision of the pancreas gives rise to a severe and rapidly fatal diabetes, 

 which presents many similarities to the severer cases of diabetes in man. 

 Owing to the fact that the tissues of a diabetic are extremely prone to in- 

 fection, it is often difficult after total excision of the pancreas, when diabetes 

 has been set up, to procure healing of the wounds without suppuration. 

 The operation is therefore usually carried out in two stages. In the first 

 stage one small portion of the tail of the pancreas is transplanted under the 

 skin of the abdomen, while the rest of the gland is excised. Such animals 

 do not get diabetes and therefore recover quickly from the operation. When 

 the wounds are quite healed the transplanted portion is removed through a 

 simple skin incision. The second operation is followed in a few hours by the 

 appearance of a large amount of sugar, 5 to 10 per cent., in the urine. The 

 glycosuria persists, the animal rapidly wastes, and finally dies at the end 

 of two or three weeks from diabetic coma. From the nature of the operation 

 it is evident that the condition of diabetes observed under these circumstances 

 has nothing to do with the presence or absence of the pancreatic secretion 

 from the intestine, since this secretion is cut off at the first operation, and 

 diabetes does not make its appearance until the second small portion of the 

 gland is removed. Moreover ligature of the ducts of the pancreas or obstruc- 

 tion of the ducts by the injection of melted paraffin does not give rise to 

 diabetes. The excretion of sugar by the kidneys is due to an increase in the 

 sugar content of the blood. The blood-sugar may amount to between 4 and 





