402 PROCESSES INFERRED FROM DIRECT OBSERVATION 



complete atrophy of the secreting epithelium, the Islets of Langerhans 

 alone remaining unimpaired. Under these circumstances no glycosuria 

 occurs, but if this atrophied remainder of the gland be removed typical 

 pancreatic diabetes at once occurs. When the pancreas is only parti- 

 ally removed the overstrain upon the remainder of the tissues leads to 

 their degeneration and the symptoms, possibly slight at first, become 

 progressively more severe. According to Allen, however, if the residue 

 of pancreatic tissue be sufficient and overstrain be avoided by a diet 

 low in carbohydrates and in fats, the incidence of progressive degenera- 

 tive changes in the residual tissues may be avoided. 



The occurrence of spontaneous Diabetes in human beings has been 

 recognized from very ancient times, but the actual identification of the 

 sweet constituent of the urine as Glucose was not accomplished until 

 1838. It is characterized, it would appear, almost if not quite invari- 

 ably by a distinct Glucohemia. It is improbable that any cases of 

 spontaneous and persistent glycosuria are due solely to increased 

 permeability of the renal epithelium such as may be brought about 

 experimentally by the administration of phloridzin. The light forms 

 of diabetes resemble alimentary glycosuria except in the fact that the 

 Assimilation-limit for carbohydrates is unusually low so that glycosuria 

 recurs whenever a normal abundance of carbohydrate is ingested. In 

 such cases the mere performance of muscular work may arrest the gly- 

 cosuria. Between this light form of diabetes and the more severe 

 forms every intermediate stage may be observed, and not infrequently 

 the same patient may pass through all degrees of severity of the disease 

 successively. In most severe forms of diabetes sugar continues to be 

 eliminated on a pure protein diet and the urine may contain over ten 

 per cent, of glucose, being usually, but not invariably, dark and dis- 

 colored from the presence of other abnormal constituents arising from 

 the disordered metabolism. 



The sugar which is excreted in the severe forms of diabetes does not 

 arise from carbohydrates in the diet or in the tissues, for not only does 

 it continue on a carbohydrate-free diet, but the quantity excreted 

 per diem may be far in excess of the carbohydrates in the food and in 

 the tissues of the body added together. Thus in one experiment upon 

 a depancreatized dog Pfliiger found that out of a total excretion of 

 3097 grams of sugar only 422 grams could possibly be accounted 

 for as arising from carbohydrate reserves of the animal. The dif- 

 ference, namely 2675 grams, must have arisen from some other 

 source. Liithje even went so far as to feed a depancreatized dog com- 

 pletely upon casein. In eight weeks it excreted nearly 1200 grams 

 of sugar, only a small proportion of which, of course* could have 

 been derived from glycogen in the tissues of the animal. Since the 

 fats, upon a diet such as this, are very quickly used up, we have no 

 alternative but to assume that the sugar was derived in part from the 

 decomposition of proteins and, as a matter of fact, in the severer 

 forms of diabetes there is a decided tendency for the ratio of the sugar 



