124 GLANDS IN HEALTH AND DISEASE 



carbohydrate eaten from day to day does not the 

 blood sugar fluctuate correspondingly? A num- 

 ber of hypotheses have been advanced to explain 

 this controlling mechanism. Very recently (April, 

 1921) Dr. Langfeldt has proposed a theory which 

 includes the best elements of the theories of other 

 investigators as well as a little of his own specu- 

 lation. In essence it is this: It is evident that 

 there must be at least two controlling factors, one 

 involving the conversion of carbohydrates into gly- 

 cogen, and the other the conversion of glycogen 

 into glucose. The first part of the reaction, the 

 glycogen synthesis, is controlled by the pancreatic 

 hormone; the second, the breaking down of glyco- 

 gen to glucose, with the object of meeting the en- 

 ergy requirements of the muscles, is a more com- 

 plex affair depending for one thing upon the degree 

 of acidity of the blood. It has been shown that the 

 glycogenase, the enzyme responsible for the trans- 

 formation of glycogen to dextrose, is most active 

 when the blood is slightly acid. Ingenious physical 

 chemists have devised quantitative methods for de- 

 termining the exact state of acidity not only of 

 blood but of any liquid. If then the acidity of the 

 blood is below or above a certain optimum, the gly- 

 cogenase is not so active, and less glucose is formed 

 a rare and abnormal condition. 



On the other hand, a more common occurrence 

 is where the pancreatic hormone fails to function, 



