THE INTERNAL SECRETION OF THE PANCREAS 527 



more actively glycolytic than the blood of the general circu- 

 lation. 



While Tuckett 1 and some others have claimed that the 

 function of the pancreas is to neutralize toxic substances entering 

 the blood from the alimentary tract, or formed in metabolism, 

 as yet their results do not seem to have received general accept- 

 ance. The demonstration by Minkowski and v. Mering that 

 the blood of pancreatectomized dogs does not contain sub- 1 

 stances causing glycosuria in normal dogs, seems to still stand as 

 evidence that the glycosuria does not depend upon accumulated 

 toxic substances. Lombroso 2 disproved the hypothesis that 

 glycosuria after pancreatectomy is due to absorption of toxic 

 substances formed in the intestine because of the defective 

 pancreatic digestion, by the following experiment : The fluid 

 escaping from a pancreatic fistula of one dog was injected into 

 the duodenum of a pancreatectomized dog ; although the diges- 

 tion of the second dog was much improved, the glycosuria was 

 not reduced. 



The Internal Secretion of the Pancreas. There 

 remains, consequently, only the hypothesis that the pancreas 

 secretes some substance that directly or indirectly modifies sugar 

 metabolism, and to determine what this substance might be has 

 been the object of many investigations. Most suggestive of 

 the results obtained are those of O. Cohnheim, who discovered 

 evidence that the internal secretion of the pancreas has the func- 

 tion of activating an inactive glycolytic enzyme that is contained 

 in the liver, muscles, and other tissues. Thus, he found that 

 whereas the expressed juice of fresh muscle tissue, and the juice 

 of fresh pancreas tissue, are each alike possessed of but slight 

 glycolytic properties, yet when a small amount of the pancreatic 

 extract is added to the muscle-juice, the mixture is capable 

 of rapidly destroying dextrose. Enough destruction of sugar 

 occurs in these experiments to account fully for the great 

 amount of sugar that is daily destroyed in the human body. 3 

 The products of this glycolysis are carbon dioxide and water, 

 if an abundance of oxygen is present ; but in the absence of 

 oxygen, first alcohol, then lactic acid, and later oxybutyric 



1 Jour, of Physiol., 1899 (25), 63. 



2 Kef. in Biochem. Centr., 1903 (1), 346. 



3 Rahel Hirsch, independently of and simultaneously with Cohnheim, 

 observed that glycolysis by liver tissue is increased upon the addition of pan- 

 creatic extract. A number of observers, especially Jacoby, Blumenthal, Fein- 

 schmidt and Arnheim, claim that the liver, and possibly other organs, contain 

 active glycolytic enzymes, but it may be that these are active only because of 

 the presence in them of the pancreatic secretion brought to them in the blood. 



