CHAPTER XII 



THE REGULATING MECHANISM. NERVOUS 

 SYSTEM 



93. THE nervous system controls and regulates 

 all the organs and even the tissues of the body 

 while, at the same time, all the organs contri- 

 bute to its upkeep and nutrition. In a sense, 

 too, it binds together the various organs and 

 systems of organs so that they act harmoni- 

 ously and it confers individuality on the body 

 It is the channel, also, by which influences from 

 the external world act on the central nervous 

 organs through the organs of sense. Finally 

 it is the seat of consciousness and of all mental 

 operations. The nervous system is highly 

 specialized. At the beginning of development 

 it arises from the ectoderm of the embryo 

 and it pursues its own mode of development 

 So necessary is it to the well-being of the body 



that it is nourished and has its waste products 

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