CHAPTER XXIV. 



THE FUNCTIONAL RELATIONS OF THE PRINCIPAL PARTS OF 

 THE BRAIN. 



WE now pass from the consideration of details of struc- 

 ture to the question of their significance, and shall 

 attempt to enable the reader to form some notions 

 meagre though they may be of the way in which the 

 Brain acts in the performance of the simpler of its 

 functions. 



In this attempt we shall have to be guided by three 

 sets of facts and inferences : (1) Those gathered from the 

 study of the Anatomy of the Nervous Systems of lower 

 animals and of Man ; (2) those derived from Experiments 

 with lower animals, in which Nerves or other portions of 

 the Nervous System have been either stimulated or 

 destroyed ; (3) those reported by medical men who have 

 paid special attention to the symptoms arising from irri- 

 tative or destructive Diseases or Injuries of different por- 

 tions of the Brain in Man. 



In each of these directions our knowledge has, within 

 recent years, been making very appreciable strides and 

 is still progressing. 



In this preliminary chapter on the mode of action of 

 the Brain, the reader's attention will be called to what is 

 known concerning three sets of structural relations which 

 are of fundamental importance. 



