NERVOUS SYSTEM _ • 365 



whether there are separate sets of fibers for each of these 

 functions, but we know that in some way there are excitory 

 and inhibitory influences. The function of the nervous 

 system to excite or to inhibit is very important with reference 

 not only to the control of the organs of the body but with 

 reference to its own interaction. Co-ordination could not 

 take place without it. 



Hygiene of the nervous system. — Since the nervous 

 system is connected with every part of the body, and controls 

 and co-ordinates the work of every organ of the body, the 

 demands upon it are very great. The skeletal muscles 

 may rest during the activity of the digestive system. Or 

 the organs of the digestive system may rest while we play 

 our games or prepare our lessons. But the nervous system 

 must remain in activity or we will lose the game or fail in 

 our lesson. The nervous system therefore needs special 

 care so that in the hurry and rush of life it will not be so 

 overcrowded by work and worry that it will fail to respond 

 in a healthful way. 



Things that cause nerve strain. — Unwholesome condi- 

 tions of living, such as overeating, eating at all hours, living 

 in poorly ventilated rooms, neglect of exercise and lack of 

 sufficient sleep, smoking and the use of alcohol; these are 

 the things that materially affect the health of the nervous 

 system. 



It is often said of the business man, "he has nervous 

 prostration from overwork;" or of a student, "he is broken 

 down through overstudy." Could we know the real facts 

 we should probably see in each case that the man or the boy 

 had neglected exercise, or taken the minimum amount of 

 sleep, or was suffering from the result of both these 

 mistakes. 



While muscular exercise is refreshing and change of 

 occupation sometimes prevents undue demands on certain 

 sets of nerve elements, nevertheless every exertion costs the 



