Etiology, Predisposition, Pathogenesis. 925 



enced by a nerve center situated in the walls of the duodenum. Even in earlier 

 times an enterogenous or panereato-enterogenous origin of diabetes mellitus had 

 been assumed. 



It appears thus from the observations and experiments cited above 

 that a regular system of organs is concerned in the regulation of 

 the cleavage of sugar. The action of the liver, by which the grape 

 sugar, both that absorbed from the intestine and that formed in the 

 organism from albumin and fat, is retained by being transformed into 

 glycogen and yielded up again according to need, requires the co- 

 operation of the pancreas. This probably exerts its action by an internal 

 secretion, and substances are probably then formed which, immediately 

 or through the intermediation of the nervous system, on the one hand 

 influence the formation of glycogen in the liver, but on the other 

 hand enable the body cells, and primarily the muscle fibers, to effect 

 the cleavage of the grape sugar and finally to oxidize it. Besides these, 

 however, other organs probably also belong to the system which regu- 

 lates the blood-sugar, namely, the adrenals, the thyroid gland and the 

 hypophysis cerebri, all these sugar-regulating organs being in com- 

 munication through the nervous system. It follows that a prolonged 

 functional disturl)ance in any one link of this system might give rise 

 to diabetes mellitus, no matter whether the functional disturbance 

 originated in a lesion that could be demonstrated anatomically or 

 whether it developed without such a lesion. 



Predisposition. In the great majority of cases that have 

 so far been reported, the disease occurred in older animals. 

 Schmitt observed a dog acquire it after swimming across a 

 broad river. Heredity also appears to be of importance. 



Pathogenesis. If an excess of grape sugar passes from the 

 liver into the blood, or if the cleavage of the grape sugar is in- 

 complete a hyperglycemia follows (Preller found 0.521% of 

 sugar in the blood of a horse). The excess of the grape sugar 

 is then eliminated by the kidneys. Since the organism requires 

 a certain amount of energy for the maintenance of the vital 

 functions, it replaces the loss occasioned by the elimination of 

 the sugar in such a manner that it uses up, at least to a cer- 

 tain degree, the sugar wdiicli is formed by the disintegration 

 of the alimentary and of the organic albumin and which is prob- 

 ably more readily available, at the same time breaking up its own 

 fat in a greater degree. To this fact are due the gradually in- 

 creasing weakness and emaciation. In severe cases the sugar 

 formed from the proteids and possibly from the fat is used up 

 in always smaller amounts, which must lead to an increased 

 combustion of fats Avithout limiting the active disintegration 

 of proteids. All these factors cause not only exhaustion, but 

 also an accumulation of oxidation-products of fats (oxybutyric 

 acid, azeto-acetic acid, acetone [Geelmuyden, Sclnvarz, Magnus, 

 Levy]) in the blood and thus lead to an acid toxemia. 



The diabetic disturbance in the metabolism easily leads 

 to nutritional disturbances in the various tissues, especially in 

 the lens of the eye and in the renal tissue. The insufficient 

 tissue nutrition may further facilitate the localization of 



