CHAPTER XIX. 



THE GENERAL ANATOMY AND PHYSIOLOGY OF 

 THE NERVOUS SYSTEM. 



In the discussion of the various systems of the body so 

 far, they have been treated as acting more or less inde- 

 pendently of each other. We have now left to consider 

 that large system whose function it is to co-ordinate these 

 various systems into a harmoniously working whole. This 

 statement of the function of the nervous system covers at 

 one sweep its entire physiology, notwithstanding the mul- 

 titude of ways in which this is accomplished. Possibly the 

 most fundamental point in discussing this system is its one- 

 ness or unity. Sometimes for arbitrary reasons or for mere 

 convenience sake we speak of several nervous systems. 

 This is physiologically wrong. The entire system of nerves, 

 ganglia and higher centers are all bound together and phy- 

 siologically are a unit. This is true even in spite of the 

 fact that certain parts of this system have more or less 

 specialized functions, for even in this case the co-ordina- 

 tion and the successive subordination is finally so perfect 

 that unifying results only are reached. It seems desirable, 

 however, in order to facilitate the discussion of these 

 nervous tissues to adopt the usual classification into 



First, the cerebro-spinal system, including the brain 

 and the cranial nerves, and the spinal cord and the spinal 

 nerves. 



Second, the sympathetic system, including two chains 

 of ganglia lying along the back-bone and extending from 

 the upper cervical through the lumbar region, and the 

 nerves which emanate from these ganglia. 



Third, the sporadic system, not a connected system at 

 all, but consisting of various ganglia scattered throughout 



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