ON NERVOUS ENERGY 57 



demand is taken advantage of in the training of athletes, 

 the aim being to stimulate the production of energy by 

 suitable exercises. Both mental and physical labour 

 tend to the production of nervous energy ; but if either 

 is carried to excess, the resources of the system are 

 unequal to the strain, and chronic exhaustion ensues. 

 In countries having short hours of labour as much work 

 is usually put through as in countries having longer 

 hours. The capacity of the nervous system has its 

 limits. Long hours soon show their effects in reducing 

 the energy of the workers to a low ebb, and they have 

 less time for recovery. As a consequence they work 

 more slowly. 



" According to Pfluger, when a nerve is stimulated, 

 whether by a mechanical shock, an electrical discharge, 

 or by the action of the will, a phenomenon occurs which 

 this physiologist calls the nervous avalanche. 



" Just as a lump of snow detached from a mountain- 

 top grows as it descends the snowy slope, and when it 

 reaches the valley is of larger size than when it set out, 

 so the stimulus received by the nerve is multiplied in its 

 passage through the conducting filament, and is much 

 more intense when it reaches the muscle than it was 

 when first produced. 



" The nerve would then be a reinforcing as well as 

 a conducting apparatus : it would increase the intensify 

 of the stimuli which it transmits, as the microphone 

 increases the intensity of the sounds which pass 

 through it. 



" If Pfluger's theory is correct, and if the nerve really 

 has the power of amplifying the stimuli received by the 

 muscle, we may believe that this power is developed 

 by exercise like all the physiological functions of working 

 organs. The motor nerves of a man who devotes himself 



