276 ROLLTN T. WOODYATT 



The Nature of the Internal Secretion of the Pancreas 



Although the indirect evidence of a pancreatic hormone in health 

 whose absence or presence in deficient quantity or potency is responsible 

 for diabetes is of the most concrete sort, we have no knowledge of the hor- 

 mone itself. We know it only as something missing in diabetes and the 

 ondocrin function of the pancr/eas so far as we know anything about it at 

 all, is simply that which is responsible for what fails to occur in the dia- 

 betic metabolism. The defect of the metabolism which characterizes 

 diabetes is a single specific defect: a failure on the part of the body to 

 oxidize, reduce, polymerize, or otherwise chemically alter a normal per- 

 centage of the glucose supplied to it in excess of a certain quantity. In 

 the most complete cases of diabetes glucose molecules enter into the chem- 

 ical reactions of the body, figuratively speaking, like so many glass beads. 

 Liberated in the body or introduced into it from without, they rattle 

 about until they fall out through the kidneys. This defect is present in 

 some degree in every case of diabetes. When present, we are justified 

 in speaking of diabetes. When absent, we may not speak of diabetes. 

 There is no other known defect of the metabolism of which this can be 

 said. Accordingly, the endocrin function of the pancreas, so far as 

 knoivn, is a single highly selective function having to do with the chemical 

 activation or dissociation of a single specific sugar glucose and nothing 

 else. 



Possible Mechanism of Its Action. A parallel to the behavior of the 

 normal and diabetic body which is suggested by Van Slyke's study of the 

 enzyme urease is probably more than a mere scheme of illustration. Let a 

 narrow dialyzing bell be partly filled with water and immersed in a beaker 

 of water. Add to the water in the bell, which is closed at the bottom by a 

 dialyzing membrane, a suitable quantity of urease. Add to the enzyme 

 containing solution a small quantity of urea. Splitting begins and pro- 

 ceeds at a certain velocity. The addition of more urea accelerates the 

 reaction and so on with successive additions until finally a point is reached 

 at which further additions accelerate it no more. All of the enzyme pres- 

 ent is then engaged in maximum activity. Further additions of urea now 

 increase the quantity and concentration of urea in the dialyzer more 

 rapidly than earlier additions. When this point is reached the diffusion 

 of unchanged urea through the membrane which has been rising but little 

 should rapidly accelerate. If in such an apparatus one were to plot the 

 curve of urea diffusion into the beaker, one would obtain a curve resem- 

 bling that of glucose excretion by the body under an increasing glucose 

 supply. If there were much urease present, the curve would rise more 

 gradually and much urea would be required to reach the limit of accelera- 

 tion of splitting. With little enzyme present, the curve would be short 



