PHYSIOLOGY OF THE NERVOUS SYSTEM 315 



The development of secondary reflexes probably consists in the es- 

 tablishment of fixed pathways for impulses through the nervous system. 

 Through the branching of the nerve fibers many pathways are open to 

 the impulses. But in repeating the same kind of action the impulses 

 are guided into particular paths, or channels. In time these paths be- 

 come so well established that the impulses flow along them without 

 conscious direction and it is then simply necessary that some stimulus 

 starts the impulses. By following the established pathways, these reach 

 the right destination and produce the desired result. According to this 

 view, secondary reflex action is but a higher phase of ordinary reflex 

 action a kind of reflex action, the conditions of which have been 

 established by the mind through repetition. (See functions of the 

 cerebellum, page 317.) 



Habits. People are observed to act differently when 

 exposed to the same conditions, or when acted upon by the 

 same stimuli. This is explained by saying they have differ- 

 ent habits. By habits are meant certain general modes 

 of action that have been acquired by repetition. Certain 

 acts repeated again and again have established conditions 

 in the nervous system which enable definite forms of action 

 to be excited, somewhat after the manner of reflex action. 

 On account of habits, therefore, the actions of the indi- 

 vidual are more or \QSS predisposed. What he will do under 

 certain conditions may be foretold from his habits. Habits 

 simply represent a higher order of secondary reflexes 

 those more closely associated with the mental life and 

 character than are the lower forms. 



Habits, in common with other forms of secondary reflex 

 action, serve the important purpose of economising the nerv- 

 ous energy. However, if pernicious habits are formed 

 instead of those that are useful, they are detrimental from 

 both a moral and a physical standpoint. Youth is recog- 

 nized as the period in which fundamental habits are formed 

 and character is largely determined. Therefore parents 



