SECRETION OF THE DUCTLESS GLANDS. 889 



affected. They show signs of hyaline degeneration or atrophy, or 

 in severe cases may be absent altogether. It should be added that 

 this connection of the islands of Langerhans with the internal 

 secretion of the pancreas is not accepted by all writers. Cases 

 of diabetes are reported in which the islands were apparently not 

 affected,* and several observers f contend that the islands represent 

 stages in the development of the ordinary secreting alveoli of the 

 pancreas. The most complete histological work seems to show 

 clearly that the islets are permanent organs which persist as such in 

 the pancreas, and presumably have, therefore, some specific func- 

 tional importance, but the nature of this function and its relation 

 to that of the acinar cells must be considered at present as open 

 questions. J 



Several theories have been advanced to explain the action of 

 the internal secretion of the pancreas. It has been suggested that 

 the secretion contains an enzyme which is necessary for the hydrol- 

 ysis or oxidation of the sugar of the body, and in the absence of 

 this enzyme the sugar accumulates in the blood and is drained off 

 through the kidney. The long series of experiments that have 

 been undertaken to establish this point of view have yielded contra- 

 dictory and perplexing results. Observations from several sources 

 indicate that the tissues of a depancreatized dog are still able to 

 consume the sugar of the blood in some degree; that is to say, 

 the tissues can take up sugar from the blood circulating through 

 them, but to what extent this sugar is metabolized remains un- 

 determined. Apparently something is lacking in the normal 

 process, but as the nature of the normal process is itself incompletely 

 known, the defect caused by the failure of the pancreatic hormone 

 becomes correspondingly difficult to define. Other investigators 

 adopt an entirely different view of the relation of the pancreas to 

 carbohydrate metabolism. They believe that the internal secre- 

 tion of the pancreas regulates in some way the output of sugar 

 from the liver. In the absence of this secretion the liver gives off its 

 glycogen as sugar too rapidly, the sugar contents of the blood are 

 thereby increased (hyperglycemia) above normal, and the excess 

 passes out in the urine. A specific form of this hypothesis (Zuel- 

 zer||) assumes that the ouput of sugar from the liver (glycogenol- 

 ysis) is under the control of two opposing hormones, an accelerat- 

 ing hormone (epinephrin) furnished by the adrenal glands, and an 



* See Pratt, "Journal of the American Medical Association," December 17, 

 1910. 



t Dale, "Philosophical Transactions," B. cxcvii., 1904; also Vincent and 

 Thompson, "Journal of Physiology," 1906, xxvii., xxxiv. 



t Bensley, "American Journal of Anatomy," 12, 297, 1912. 



See Macleod and Pearce, "American Journal of Physiology," 32, 184, 

 1913, and 33, 378, 1914; also Verzar, "Biochemische Zeitschrift," 66, 75, 1914. 



|| Zuelzer, "Deut. med. Wochenschrift," 34, 1380, 1908. 



