CHAPTER III 



A GENERAL VIEW OF THE NERVOUS SYSTEM 



21. The great distinguishing feature separating man 

 as an animal from all other animals is, as we have seen, 

 his possession of a nervous system of more complex and 

 intricate structure than any other in the animal kingdom. 

 It is now fully recognized that the nervous system is the 

 central, unifying, coordinating element in the human 

 organism that for which all other parts exist and to 

 which all are subordinate. In order, therefore, to under- 

 stand clearly the part which each portion of the body is 

 designed to play in the general plan, it is necessary to 

 have some general knowledge of the nervous system, 

 while a fuller study of its parts and their functions may 

 be postponed to a later period. 



22. Divisions of the Nervous System. Physiologists have 

 been accustomed to describe two great divisions of the 

 nervous system, called the central or cerebro- spinal sys- 

 tem, and the ganglionic or sympathetic system, the first 

 having control of sensation and voluntary motion, the 

 second presiding over those vital operations not under 

 voluntary control, its nerves being in general distributed 

 to the internal organs and the blood vessels. It has, 

 however, long been understood that there are not two 

 nervous systems, but one. Still, as a matter of conven- 

 ience in description, the well-known terms are generally 



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