496 THE HUMAN BODY 



resulting glycosuria. This suggests, of course, that the liver 

 carries on its function of storing and delivering sugar under the 

 control of a reflex " center." Such a method of control seems 

 reasonable inasmuch as increased activity of the tissues involves 

 increased consumption of sugar, with a greater call upon the liver 

 for supplies, and, as we know, the tissues most involved, the 

 muscles, send into the medulla streams of afferent impulses when- 

 ever they are active, which would serve to excite the center. In 

 corroboration of this idea it may be stated that certain diseases 

 of the central nervous system in man result in an upset of the liver 

 function of precisely this sort. 



Recent observations have brought out the interesting fact that 

 this "nervous control" of the conversion of glycogen to sugar by 

 the liver, is not direct, but operates through the intervention of 

 the hormone adrenin. Some time ago the discovery was made 

 that during great emotional excitement sugar is apt to appear in 

 the urine. A test was made recently on the members of the foot- 

 ball squad of a great university immediately following the crucial 

 game of the year. Of the men examined, players and substitutes, 

 nearly all showed pronounced glycosuria. This fact, in conjunc- 

 tion with the known outpouring of adrenin in times of stress, sug- 

 gested a causal relationship, and the demonstration was shortly 

 afforded that the increased production of sugar from liver glycogen 

 is the result of stimulation by the hormone. This we recognize at 

 once as a part, and an important part, of the general emergency 

 reaction of the Body. At a time when the utmost muscular exer- 

 tion is likely to be demanded it is imperative that there be no fail- 

 ure from a shortage of fuel. The flooding of the blood with 

 sugar as the result of the outpouring of adrenin assures that the 

 fuel supply for the laboring muscles shall be ample. That there is 

 an overproduction, so that much passes out by the kidneys and is 

 wasted, merely emphasizes the general principle that in time of 

 emergency the Body scorns economy, directing its resources 

 lavishly toward successful meeting of the immediate situation. 



Glycosuria from Inability of the Tissues to Use Sugar. Di- 

 abetes Mellitus. This condition, the usual pathological cause of 

 glycosuria, and unfortunately not of rare occurrence, has been 

 much studied, chiefly because it involves the relation of the tissues 

 to their chief fuel supply, sugar, and a complete understanding of 



