PART IV 



THE NERVOUS SYSTEM 



All our previous study has had to do, directly or in- 

 directly, with the nervous system, with its methods of 

 action, its instruments, its nutrition, its arrangement and 

 functions. Now we are to examine its wonderful and 

 delicate mechanism more in detail, to inquire further into 

 the functions which the various parts fulfill, and into the 

 manner of life which study and experience have shown to 

 be most conducive to the preservation of the most impor- 

 tant part of the human organism in health and efficiency. 



Even the limited amount of knowledge upon this great 

 subject which is within the reach of young students may 

 be made valuable in enforcing the necessity of hygienic 

 living, and also as a basis for a ready appreciation of that 

 larger revelation respecting the nervous system which 

 science will from time to time unfold. 



In presenting this fuller description of the nervous 

 system some repetition of the statements given in Chap- 

 ter III is found necessary. 



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