CHAPTER XX 

 THE NERVOUS SYSTEM 



General arrangement. Although there are millions 

 of separate cells in the human body, each doing its indi- 

 vidual task, yet they ail work together harmoniously. 



FIG. 116. Right side of brain and upper portion of spinal cord. 



The co-operation of all these minute activities is made 

 possible by means of a master tissue, the nervous system. 

 By its many branches, the nervous system reaches every 

 cell to detect its needs and control its activity. Like 

 the circulatory system, the nervous system consists of 



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