782 PHYSIOLOGY OF DIGESTION AND SECRETION. 



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. Cohnheim* states that, while the juices ex- 

 pressed from muscle and from pancreas have little effect upon sugar 

 when taken separately, yet when combined they cause a marked 

 disappearance (glycolysis) of sugar added to the mixture. The 

 inference from this result is that the pancreas furnishes a substance 

 which activates the glycolytic enzyme or enzymes of the muscle 

 and thus makes possible the physiological consumption of sugars 

 in the body. Since the pancreas extracts do not lose this property 

 upon boiling it is evident that the activating substance is not an 

 enzyme, but a body of a more stable character. 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 (and other sugar-producing organs). 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 (hypergly- 

 cemia) above normal, and the excess passes out in the urine. 



Kidney. Tigerstedt and Bergman f state that a substance 

 may be extracted from the kidneys of rabbits which when injected 

 into the body of a living animal causes a rise of blood-pressure. 

 They get the same effect from the blood of the renal vein. They 

 conclude, therefore, that a substance, for which they suggest the 

 name "rennin," is normally secreted by the kidney into the renal 

 blood, and that this substance causes a vasoconstriction. 



* Cohnheim, "Zeitschrift f. physiolog. Chemie," 39, 336, 1903; also 1904. 

 t " Skandinavisches Archiv f . Physiologic, " 8, 223, 1898 ; see also Brad- 

 ford, "Proceedings of the Royal Society," 1892. 



