THE METABOLISM OF CARBOHYDRATES 805 



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 

 5 parts per 1000. This state of hyperglycsemia and the excretion of sugar 

 in the urine persist even when the animal is completely starved or is fed on a 

 pure protein or protein plus fat diet. Moreover, as in phloridzin glycosuria, 

 we find a constant ratio between the sugar and the urinary nitrogen, the D : 1ST 

 ratio being usually about 2-8. The administration of protein food to an 

 animal previously starved increases the output of nitrogen, but increases 

 at the same time the output of glucose. No similar increase in the glucose 

 excretion is observed as a result of the administration of fat. We must 

 conclude therefore that in the absence of carbohydrate from the diet the 

 excess of sugar in the blood as well as that escaping by the urine is 

 derived from the breakdown of the proteins of the tissues. On the other 

 hand, the power of the animal to assimilate or utilise carbohydrate is 

 diminished and sometimes entirely abolished, so that glucose administered 

 to a starving animal with pancreatic diabetes may appear quantitatively 

 in the urine. The amount taken by the alimentary canal is simply added 

 to the amount which would have been excreted if no food had been given. 

 In most cases, at any rate during the first week after total extirpation, there 

 is apparently still some power of carbohydrate assimilation, since adminis- 

 tration of glucose causes a transitory rise in the respiratory quotient (Moor- 

 house). Glycogen disappears entirely from the liver ; but the muscles, 

 especially the heart, may contain a normal or an increased amount of 

 glycogen. There is a rapid wasting of all the tissues of the body, including 

 the fats and proteins, and. finally the animal is destroyed by the accumulation 

 of the products of imperfect oxidation of the fatty acids. 



It is still very difficult to say definitely why removal of the pancreas 

 brings about this condition or what disturbance of metabolism is primarily 

 responsible for it. Two views have been put forward. According to one, 

 the primary disturbance is the diminished or absent power of utilisation 

 of sugar by the tissues ; according to the second, an increased production 

 of sugar by the liver. There is no doubt that in the diabetic animal the 

 power of utilising carbohydrates is deficient. This is shown by the low 

 respiratory quotient and by the fact that administration of glucose to 

 the animal causes an almost corresponding increase in the amount of 

 glucose excreted in the urine. But the loss of power of utilisation is not 

 absolute, at any rate in the first week of the disorder. Administration of 

 glucose causes a slight and temporary rise in the respiratory quotient, 

 and if 20 gms. of glucose be administered, it is often possible to recover 

 only about 15 to 18 gms. from the urine. Moreover the increased amount 

 of glycogen in the heart muscle of diabetic dogs points to a persistent 

 power of assimilation of sugar by this organ. The heart from a diabetic 

 animal, if fed with its own blood, can be shown to use up not only the 

 sugar circulating in the blood but also its store of glycogen, and this utilisa- 



