The Intimate Causes of Old Age. 233 



because they are literally tired to death. After educa- 

 tion begins, the brain cells are rarely or never sufficiently 

 rested from day to day, and there follows what may be 

 termed cumulative fatigue. Improper food taken at bad 

 hours, with abnormal excitements and untimely stimula- 

 tion play their part, with the general result that there is 

 as an increment of unrelieved fatigue going over from 

 week to week and month to month, until an abnormal 

 condition is reached where restful sleep is no longer 

 possible. 



In typical American cases, these cumulative effects of 

 unrelieved fatigue begin in youth and set up a series of 

 changes in the brain cells which result either in the popu- 

 lar "nervous prostration," or more frequently, in an 

 abnormal shrinkage of the mental life, a diminution of 

 personality, accompanied by sub-innervation and lowered 

 vitality. 



In this latter condition the organism is dangerously 

 subject to invasions of the disease bacteria. This lowered 

 vitality from insufficient or faulty innervation — the result 

 of chronic biain fatigue — is primarily the cause of many 

 prevalent diseases, since the germs of these diseases are 

 always quite constantly present, and whether they are 

 resisted by the nervous aura and destroyed by phagocitosis 

 or not, is largely a question of normal as against sub- 

 normal innervation. 



This condition is often set up in children at school. 



