1U4 THK NKKVOUS SYSTKM AND ITS COXSKKVATION 



promptly and fully through the lungs. But the other acid 

 products may now be present to an extent which suffices to 

 render the muscles less responsive to central command. The 

 -ame or similar compounds may have affected the motor 

 end-plate- in such a way as to make difficult the trans- 

 mi<-ion of effects from nerve to muscle. If a blockade is 

 established at this point, muscular response may fail at a 

 time when then' is yet plenty of potential working capac- 

 ity in the muscles themselves. It is generally held that 

 this is just what occurs: the end-plates become imper- 

 vious to stimuli, while other parts of the apparatus are 

 still in fair working order. 



One is tempted to draw a comparison between the end- 

 plate and a safety-fuse, such as is used in connection with 

 an electric fixture. The fuse is intended to be destroyed 

 under conditions which might otherwise threaten damage 

 to more valuable portions of the system. It is readily 

 renewed. So we may think of the end-plate as some- 

 thing easily impaired by use, but also easy to repair. It 

 is better that wear and tear should fall upon this structure 

 rather than upon the more highly organized protoplasm 

 of nerve-cells or muscle-fibers. \Ye may now assign as 

 one condition associated with our walker'- painful prog- 

 ress the increasing difficulty of end-plate transmission. 



Another condition is operative at the same time. This 

 is the persistent return from the musculature itself, the 

 joints, :uid the soles of the feet of afferent impulses in- 

 hibitory to continued walking. In part these impulses 

 give ri-e to sensations of lameness and weariness. In 

 part they may impede action without having their sign 

 manifest in consciousness. Fatigue, so far as it is due 

 to impulse- of this class, may be regarded as disinclination 

 rather than incapacity. If we are ingenuous we must 

 admit that much of our fatigue has to be classified under 

 tlii- head. Such a source of deterrent impulses as a blis- 

 tered foot has a double effect upon the sufferer. Resides 

 making him feel disposed to -top, il causes him to adopt 

 an unnatural gait in the endeavor to "favor" the injured 



