THE INTERNAL SECRETION OF THE PANCREAS 419 



observed glycogen in another form, and for this reason the ex- 

 planation of the levulose experiments must lie in some cause 

 other than the formation of a different glycogen substance. 

 Fraenkel draws attention to Henri's experiments, which have 

 attracted little notice, and which show that levulose has an in- 

 hibitory influence upon the action of invertin. This result sug- 

 gests that levulose may have an inhibitory effect upon the fer- 

 mentative processes in the liver. 



Liberation of the glycogen reserves cannot be the only source 

 of the increased sugar contents of the blood, for these are 

 independent of the conditions governing glycogen in the organ- 

 ism. After the exhaustion of the glycogen reserves and the rapid 

 excretion of any carbohydrates which may have been present in 

 the food, the source of the surplus sugar in the blood can only lie 

 with the albuminoids and fats. Given a diet free from carbo- 

 hydrates and rich in albumin, it is possible that glycogen would 

 be formed as an intermediate stage in the conversion of albumin 

 into sugar. This line of argument is excluded where the diet 

 consists of fats, yet in this case also the glycosuria and hyper- 

 glycaemia are considerable. 



The defective metabolism of the carbohydrates is the principal 

 cause of another important symptom of diabetes, namely, the 

 increase in the amount of the acetone bodies (oxybutyric acid, 

 aceto-acetic acid, acetone) present in the urine, or, as it is called, 

 the acidosis. Under normal conditions, the acetone bodies are 

 formed, in part from the amino acids of the albumin (Embden), 

 but principally free from oleic acids, as an intermediary product 

 in the conversion of fat into carbohydrates. Although the cause 

 is at present unknown, it is an undoubted fact that ketonuria, 

 that is, excretion of the acetone bodies in the urine, takes place 

 only when decomposition of the carbohydrates in the economy has 

 ceased. This explains the occurrence of acetonuria in inanition 

 and in those pathological conditions in which the nutritional con- 

 ditions in general, and the assimilation of the carbohydrates in 

 particular, are very much reduced. In severe diabetes, in addition 

 to the carbohydrates contained in the diet, the major portion of 

 the sugar obtained from other sources is also excreted ; thus there 

 is an enormous increase in the formation of acetone substances 

 and, consequently, ketonuria of a very pronounced character. 



The overloading of the blood with oxybutyric acid and aceto- 

 acetic acid gives rise to acid intoxication, which Naunyn and his 

 school regard as the cause of diabetic coma. The organism of 

 carnivora possesses a chemical protective substance in ammonia, 

 which is formed by the decomposition of the albumin molecule, 

 and this substance is able to neutralize the superfluous acids. In 

 consequence of this, the increased production of acids increases 

 the ammonia in the urine at the expense of the urea. But the 

 amount of the ammonia is insufficient to combat the continued 

 formation of acids, and a demand is made upon the fixed alkalis 



