48 INTERNAL SECRETION 



Adami affirms that he has encountered appearances in the 

 human subject which would be difficult to explain, except on 

 the hypothesis that the islands are not separate organs ; that 

 they vary in number according to the state of nutrition and 

 activity of the gland, becoming converted into active acini, and 

 vice versa. As Adami justly points out, these observations do 

 not wholly negative the contention that the islands bear some 

 intimate relationship to a certain order of cases of diabetes ; 

 they suggest, however, that degenerative changes seen in 

 them are an indication of other changes occurring in the 

 intimately connected pancreatic tissue proper. 



Whatever may be subsequently discovered to be the true 

 function of the islets of Langerhans, their intimate anatomical 

 relationship with the zymogenous tubules, the numerous 

 transition forms in all groups of vertebrates, and the transforma- 

 tion of alveolus into islet, and vice versa, all appear to prove 

 conclusively that the islets are not organs sui generis, but are 

 an integral part of the pancreatic tissue. As to whether the 

 temporary structural modification of alveolus into islet tissue 

 corresponds to a specialization of function, the evidence is at 

 present inconclusive. 



A prolonged discussion of the pathology of glycosuria and 

 speculations as to the precise manner in which the internal 

 secretion of the pancreas normally prevents such a condition, 

 would serve no useful purpose. It is, however, of supreme 

 importance to bear in mind that a certain order of cases of 

 diabetes mellitus are, in all probability, due to insufficiency 

 of the internal secretion of the pancreas. But we must bear 

 in mind the possible influence of disturbances in certain others 

 of the endocrine glands which are concerned with carbohydrate 

 metabolism, as, for example, the adrenal and the thyroid. 

 In disease of the pancreas the limit of assimilation for carbo- 

 hydrate may be greatly lowered even when spontaneous 

 glycosuria does not occur. 



The symptoms of diabetes as observed in the human subject 

 are well known, and need only be referred to briefly. The 

 cases are described as acute and chronic, the former usually 

 occurring in children, the latter usually in older people. There 

 are mild and severe cases, and there are the fat or emaciated 

 cases. Many other subdivisions and classifications have been 

 suggested. Polyuria, thirst, increased appetite, dry ness of 



