408 THE NERVES AND THE SENSE ORGANS 



suffer with him, and he swells the numbers of the insane 

 and dependent people for whom society has to care, 

 but who can give back nothing in return. 



We have already learned that the cigarette injures 

 the organs of respiration ; its effect is much worse upon the 

 nervous system, especially upon that of young people. 

 Our nervous system must develop with our years. As 

 we acquire skill, new nerve connections are developed, both 

 in the organs and in the central system. The nerve cells 

 of the boy who uses cigarettes do not grow properly, and 

 the chances are against his " making good.' 7 Instead of 

 becoming alert and ready, he is more likely to lose ground, 

 and to become backward and indifferent. Only a small 

 per cent (less than 7) of the school children who smoke are 

 able to keep up their work. How can such children ex- 

 pect, later, to satisfy their employers or customers, and 

 to make a good living? It is not for nothing that the best 

 athletic trainers refuse to let athletes use tobacco. An 

 athlete needs steady nerves, "wind," strength, and the 

 ability to decide quickly; if he wishes to develop these 

 qualities to their fullest extent, he should let tobacco 

 alone. 



408. Exercises. 



1. What advantage does the body derive from a central nervous 

 system? What advantage does a telephone system derive from a 

 central station? Is there any disadvantage in either case? 



2. Give other illustrations, besides the one given in 404, of the 

 fact that the mind can choose what stimuli it will send back to the 

 muscles. 



3. How do you account, for the fact that you can recall a " for- 

 gotten" event by a hard effort of the memory? 



