CHAPTER XVIII 

 THE NERVOUS SYSTEM 



Without the nervous system, the human body would be in 

 the lamentable condition of a fully equipped factory with 

 plenty of willing workmen, which stands idle because of the 

 lack of a manager. Not a motion in the whole mechanism 

 would be possible and not an impulse or thought be experi- 

 enced. If the body were not alive, this want of power of 

 motion would be perfectly natural, but in the living body this 

 helplessness through lack of direction is one of the saddest of 

 sights. A yet sadder one is that of a living body showing a 

 large amount of activity, but not properly regulated. Such 

 a condition we sometimes see in idiots or insane people : life 

 in plenty, action in abundance, but all ill-applied and reach- 

 ing no useful end. It is as if the factory were running night 

 and day, burning coal and using up material, but turning out 

 no useful product. 



The functions of the nervous system are numerous. It 

 must direct and control all visible movements; it must also 

 control many invisible activities like the secretions of glands, 

 the movements of the intestine and the beating of the heart. 

 It is, moreover, concerned with higher functions, such as 

 feeling, thinking, remembering, willing and other mental 

 acts, many of which, though- frequently never apparent in 

 action, make up the most important part of our lives. 



The central nervous system consists of the brain and spinal 

 cord, which are not separate organs but parts of the same 

 mass of tissue, and contain most of the nerve cells con- 

 cerned in the higher functions. The delicate structures of 

 the central nervous system are placed within strong protect- 

 ing bones, but that they may have communication with the 



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