CHAPTER XVII 

 VITAL RESERVES 



The human individual lives usually far within his limits; 

 he possesses powers of various sorts which he habitually fails to 

 use. He energizes below his maximum^ and he behaves below 

 his optimum. 



— William James 



VITAL processes in general involve the ac- 

 cumulation of certain reserves of material 

 and energy whose expenditure may on oc- 

 casion improve the efficiency of action. Reaction is 

 not merely transfer of energy applied at the re- 

 ceptor surface and released at the effector organ like 

 the working of a lever. The living body is constantly 

 accumulating a reservoir of potential. A slight stimu- 

 lus may tap this reservoir and be followed by a tor- 

 rential expenditure of energy quite out of proportion 

 to the pull that opens the valve (Herrick, 1924, chap, 

 xix). 



The mechanisms of "trigger action" of this sort are 

 amplified and enormously complicated in the nervous 

 systems of higher animals. The cerebellum appears to 

 be fundamentally such a storehouse of nervous re- 

 serve which is drawn upon automatically during the 

 progress of all muscular activity. 



These reserves are not necessarily static, mere 

 potential energy of position. They may be as dynamic 



31a 



