THE METABOLISM OF CARBOHYDRATES 911 



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 obstruction 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 : N ratio being either 2-8 or 3'65. 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 entirely 

 abolished. Glucose or dextrose administered to a starving animal 

 with pancreatic diabetes appears 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. Glycogen 

 disappears entirely from the liver ; and the tissues generally, though 

 bathed in a blood containing double its normal content of sugar, are 

 unable to assimilate the sugar and to build it into glycogen, or to take 

 it up into the cells in the form which is the necessary condition for 

 its utilisation. Though plentifully supplied with sugar, they suffer 

 from sugar starvation and react in the same way as when the sugar 

 starvation is induced by a diet consisting purely of fats or by a drain 

 of sugar from the body in consequence of abnormal functioning of the 

 kidneys. The results are exactly analogous to those we have studied 

 in the case of phloridzin diabetes. 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. The liver apparently uses 

 up the proteins, the ammo-acids, and some of the lower fatty acids, 

 e.g. acetic, propionic, and lactic, and glycerin, for the manufacture of 

 the sugar that the tissues lack ; but all to no purpose, since these 

 tissues are unable to utilise any of the sugars so formed. 



Why removal of the pancreas brings about this disability to 

 assimilate sugar is still a matter of speculation. It is generally 

 assumed that the pancreas, in addition to the manufacture of a diges- 

 tive juice, produces an internal secretion, a hormone, which passes 



