266 THE GLANDS REGULATING PERSONALITY 



as the large employers of labor, and their employment managers 

 have given much thought to the problem of fatigue. Just what 

 fatigue is, why different individuals tire at different rates, why 

 some are constructed for monotonous routine while others must 

 have constant variety and change, the relation to accidents and 

 to quantity output, are a few of the major lines of inquiry upon 

 which the endocrines obviously have a large bearing. To the 

 employment manager, labor turnover and the selection of per- 

 sonnel are adjacent fields of research. 



Fatigue as an endocrine deficiency — a depressed state of one or 

 more of the glands of internal secretion, abolished when its normal 

 functioning is restored — is a general principle from which de- 

 partures of exploration of sub-problems will proceed. An en- 

 docrine organ will secrete at a certain rate. When it is stimulated 

 excessively, it will eject extra amounts of its secretion. How long 

 the period of excessive stimulation may last must depend upon 

 the secretion potential or margin of reserve of the cells, varying 

 from organ to organ, and from individual to individual. After 

 that, exhaustion and failure follows, with the onset of the symp- 

 toms of fatigue. 



A pretty demonstration of this process has been worked out 

 in the electrical stimulation of muscle. If a muscle, say the 

 biceps, is irritated by an electric current, it will contract. As 

 the strength of the current is increased, the degree of contraction 

 becomes greater. A sort of stepladder effect of increasing con- 

 tractions may be thus obtained. After a time, the electric she 

 cannot cause a greater contraction, but only a lesser. And if con- 

 tinued, the muscle will cease to function because of fatigue. 

 If now, when the muscle begins to lag in its response, and its 

 contractions to decrease, one injects into a vein extracts of 

 thyroid, parathyroid, or adrenal glands, they will immediate 

 ra inviflo r a to the failing contractions. The injections must be 

 made before the fatigue is < bo the point of abso! 



haustion. It follows that these glands normally pour into I 

 circulation m I which counter tTect of 1 in- 



stances, and in fact make possible muscular rc< •uperation from 

 /in- throughout U M bl emergencies and crises, 



•ionallv red thing a« 



urgent. As such it means l violent mining of the endocr 

 Is. But ' also ft chronic fatigue, which has been (fif- 



I d with ' 

 asked for someone to kill him the name of the germ causing the 



