INFLUENCES WHICH AFFECT THE MIND 313 



SUMMARY 



1. Constant effort of the will is needed to keep the thought 



cells of the brain acting. 



2. A few repetitions of either good or bad acts produce 



habits of doing them. 



3. Many mental acts are done without consciousness. 



4. In sleep the thought cells rest from work and there is 



complete unconsciousness. Lack of mental occupa- 

 tion during the day, worry, and an empty stomach 

 are common causes of sleeplessness. 



5. A change of occupation is rest for the mind. 



6. Active exercise, short of fatigue, improves the mind 



as well as the body. 



7. A lack of self-control when irritated by slight sensa- 



tions is nervousness. An extreme lack of will power 

 is hysteria. 



8. A persistent lack of control of the thoughts is 



insanity. The thoughts may either be hastened, or 

 hindered, or suppressed, giving rise to three forms 

 of the trouble. 



9. In fevers there is often a temporary delirium which 



resembles insanity. 



10. In old people, an artery of the brain sometimes bursts, 



and the clot, pressing upon the nerve cells, stops 

 their action and produces a shock of apoplexy. 



11. Irritation of the motor region may cause the cells to 



send orders for violent muscular movements, pro- 

 ducing a fit or convulsion. 



REVIEW TOPICS 



I. State how the cells of the cerebrum differ from the 

 other cells of the body in regard to being controlled 

 and made to act. 



