The Internal Secretion of the Pancreas 127 



come into very close relation — indeed, in actual contact — with the walls 

 of the blood capillaries. If the duct of the pancreas is tied, the ordinary 

 alveolar tissue disappears after a time, although for a long while there are 

 remains of the ducts. But most observers are agreed that the islet tissue 

 does not — at least to any great degree — participate in the atrophy of the 

 alveoli, and the statement that it persists under these circumstances — 

 although denied by some authors — is generally accepted. 



Effect of Surgical Removal of Pancreas. Diabetes 



Since the discovery in 1889 by v. Mering and Minkowski that removal 

 of the pancreas, or even of the greater part of the organ, is immediately 

 followed by hyperglycemia leading to severe and fatal diabetes, whereas 

 this effect is not obtained from mere ligature of the duct (in spite of 

 the disappearance of all the alveolar tissue and the complete cessation of 

 formation of pancreatic juice), attention has been especially directed to the 

 islet tissue as the probable source of an internal secretion which serves 

 to regulate carbohydrate metabolism. For, as has just been stated, the 

 cirrhosed and atrophied gland which remains after ligature of the duct 

 contains none of the ordinary secreting epithelium, except perhaps that of 

 a few remaining ducts, but does, in all probability, still contain the islets 

 of Langerhans. Nevertheless, this atrophied gland is sufficient to furnish 

 the internal secretion which regulates carbohydrate metabolism, so that 

 this is maintained normal for an indefinite time. But if now the atro- 

 phied gland is removed, diabetes at once shows itself. Further, if a portion 

 of pancreas, whether thus atrophied or not, be successfully transplanted 

 to another site and the rest of the gland be then removed, diabetes does 

 not occur — although on removal of the graft it immediately makes its 

 appearance. The evidence for the action of an internal secretion which is 

 '' yielded by the gland — and in all probability by its islet tissue, — and serves 

 i v to maintain carbohydrate metabolism in a normal condition, is therefore 

 very complete. In support of this conclusion it has frequently been noted 

 in cases of diabetes in man that the cells of the islets have undergone some 

 kind of degenerative change. 



If the pancreas removal is complete, the percentage of sugar in the urine 

 is very large, even during fasting or on carbohydrate free diet. Minkowski 

 found the relation of dextrose to nitrogen in the dog under these circum- 

 stances to be 2 - 8 : 1. With protein diet the sugar rises (and falls) with the 

 nitrogen : with fatty foods there is an increase in the quotient : while carbo- 

 hydrates of the food are almost wholly passed out by the urine as dextrose. 

 Levulose is, however, utilised in the body to a considerable degree, and the 

 glycogen which had disappeared from the liver and muscles may to some 

 extent reappear when this sugar is given with the food. 



The glycosuria is accompanied by hyperglycemia, which is indeed the 

 actual cause of the glycosuria; but according to de Meyer the latter is 



