0'8IIEA — ASPECTS OF MENTAL ECONOMY. 55 



ascribes this want of precision, which is simply inco-ordination 

 carried to a point where it becomes noticeable, to the spasmodic 

 functioning of nerve cells in a condition of fatigue. The inhib- 

 itory apparatus does its work less efficiently; but inhibition is 

 absolutely essential for fine adaptations in motor activity. 

 The Hughlings-Jackson theory would account for the phenom- 

 enon under consideration by declaring that the co-ordinating 

 areas in the brain are unable to act with accustomed author- 

 ity, and movements result which are not so fully under the 

 direction of the will. 1 This view is strongly supported by 

 data gained from the investigations of ^losso, 2 Lombard, 3 and 

 others. But whatever the neurological explanation may be, 

 it is enough for practical purposes to recognize that the ex- 

 haustion of nerve centers results in a general lessened power of 

 delicate co-ordination of motor activities. 



Again, as was intimated above, fatigue has a retarding in- 

 fluence upon the rapidity of physical action. 4 This phenom- 

 enon is apparent in the case of athletes who are contesting 

 in activities demanding ready response to stimulus. When 

 fatigued they do not start so readily in running, or gather them- 

 selves so quickly or act with such continued force in defense 

 or offense where promptness in execution and sustained power 

 are the decisive factors. When it is realized how much of the 

 success of life depends upon quickness and certainty of action 

 in the countless situations requiring these qualities in which 

 one is placed every day no matter what his calling may be, the 

 importance of preserving to the fullest extent possible the hy- 

 giene, or perhaps better the vigor of the brain can be appreciated. 



§4. Neural Fatigue: Intellectual Effects. — While nerve de- 

 pletion has indeed a very unhappy influence upon motor abili- 

 ties, still the harm done here is probably not so great as that 



iCf. Scripture, The New Psychology, pp. 228 et seq. 

 2 Loc. cit. , 



8 Loc. cit. 



*See Scripture, op. cit., pp. 128-129, and 243 et seq.; also Bryan, on The De- 

 velopment of Voluntary Motor Ability, Am. Jour, of Psy., 1892, p. 123. 



