356 THE METABOLISM OF THE CARBOHYDRATES 



by the pancreas which acts on dextrose independent of the 

 pancreatic tissue. The small portion of transplanted gland is 

 large enough to furnish this secretion, but when this is also 

 removed diabetes immediately follows. 



Nor has this internal secretion anything to do with the 

 intestinal secretion of the gland. The transplantation experiment 

 just mentioned demonstrates this, as do other experiments, 

 such as ligature of the pancreatic duct and the establishment of 

 a pancreatic fistula, neither of which operations induces any 

 glycosuria. 



There can be no doubt, then, that the cause of the non- 

 utilisation of dextrose is the absence from the organism of some 

 internal secretion of the pancreas. This being so, it might be 

 expected that in the blood removed from a depancreated dog, 

 dextrose would be less quickly decomposed than in normal blood 

 (i.e. which contains the sugar- destroying internal secretion of the 

 pancreas). We have already seen, however, that normal blood 

 itself possesses no glycolytic power, and that the role of the 

 internal pancreatic secretion is probably only that of an acti- 

 vating substance which activates a pro-ferment produced by the 

 muscles. 



In patients dead of Diabetes mellitus, as stated above, morbid 

 changes have not infrequently been observed in the pancreas. 

 These changes have often been noticed to be especially located in 

 the isles of Langerhans, which are small rounded nests of epithelial- 

 like cells embedded in the connective tissue lying between the 

 true secreting acini. These isles have a richer blood supply than 

 the rest of the pancreatic tissue. Dale ( 21 ) is of opinion that they 

 are connected structurally with the secreting acini-; for he says 

 after he had completely exhausted the secreting cells of the 

 acini by repeatedly injecting an animal with secretin, he could 

 easily trace the connection between the two. He noticed, more- 

 over, that many of the secreting acini by this treatment became 

 very like the isles in appearance. In certain fishes, on the other 

 hand, the isles are collected together as small nodules structurally 

 isolated from the pancreas proper, the pancreas itself in such 

 cases possessing no such isles. Rennie and Eraser ( 22 ), and, later, 

 Diamare and Kubialiko ( 23 ), have investigated the physiological 

 action of these isolated isle nodules, especially with regard to their 

 dextrose-destroying action, but have not been able to discover any 



