O SHEA — ASPECTS OF MENTAL ECONOMY. 



53 



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ALTERNATINQ 



Voluntary. ElectkiC 



Fig 



7. This figure (Scripture 1 after Lombard) shows the independence of 

 muscular and voluntary fatigue. Lombard first stimulated a muscle by vo- 

 lition, then by electricity, and continued the stimulations alternately as indi- 

 cated in the figure. At first the voluntary tracings show greater force ex- 

 erted, but this is gradually lost until the effect for volition and from elec- 

 trical stimulation are about equal. Then there is a recovery of volitional 

 power, which subsides again, only to return in a sort of rhythmical period, 

 which is very apparent from the tracings. 



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FiQ. 8 shows the effect of mental work upon the power of contraction of the 

 finger at various hours of the day. (Mosso, loc. cit.) The first curve, from 

 A to B, indicates the amount of work which could be done at 9 a. m. From 

 2 p. m. until 5 :30 p. m. the subject was under great mental strain while con- 

 ducting an examination in the university. After the examination, at 5 :45 

 p. m., the curve from C to D was gained. The first contraction of the fin- 

 ger shows as much power as in the morning, but the energv is soon ex- 

 hausted. Then after supper, at about 7 :30 p. m., the increase from E to P 

 was taken, and it indicates a slight increase in the endurance of energy. 

 Finally at 9 p. m. the fourth curve was made, showing a slow recovery of 

 original power. 



This principle in its general bearings has been recognized 

 practically in every-day experience, particularly in the train- 

 ing of athletes; for it is well known that their physical vigor 

 and endurance depend in great degree upon their mental con- 

 dition (See Fig. 8), or as the saying goes, upon their nerve. 

 They are expected during the season of training to secure an 

 abundance of food and sleep, and to abstain from dissipation 

 so as to keep the nervous system in thorough repair ; and it 

 would doubtless not be an overstatement to say that athletic 

 contests are won by virtue of the power and control conferred 



1 Ibid., p. 232. The figure is a copy made by Scripture from an original rec- 

 ord furnished him by Lombard. 



