INTRODUCTION. 17 



80 habitual in the course of generations that all the 

 individuals of the same species automatically perform the 

 same actions under the stimulus supplied by the same 

 appropriate circumstances. Kational actions, on the other 

 hand, are actions which are required to meet circumstances 

 of comparatively rare occurrence in the life-history of the 

 species, and which therefore can only be performed by an 

 intentional effort of adaptation. Consequently there arises 

 the subordinate distinction to which I allude, viz., that 

 instinctive actions are only performed under particular 

 circumstances which have been frequently experienced 

 during the life-history of the species; whereas rational 

 actions are performed under varied circumstances, and 

 serve to meet novel exigencies which may never before 

 have occurred even in the life-history of the individual. 



Thus, then, upon the whole, we may lay down our 

 several definitions in their most complete form. 



Keflex action is non-mental neuro-muscular adjust- 

 ment, due to the inherited mechanism of the nervous 

 system, which is formed to respond to particular and often 

 recurring stimuli, by giving rise to particular movements 

 of an adaptive though not of an intentional kind. 



Instinct is reflex action into which there is imported 

 the element of consciousness. The term is therefore a 

 generic one, comprising all those faculties of mind which 

 are concerned in conscious and adaptive action, antecedent 

 to individual experience, without necessary knowledge of 

 the relation between means employed and ends attained, 

 but similarly performed under similar and frequently re- 

 curring circumstances by all the individuals of the same 

 species. 



Keason or intelligence is the faculty which is concerned 

 in the intentional adaptation of means to ends. It there- 

 fore implies the conscious knowledge of the relation be- 

 tween means employed and ends attained, and may be 

 exercised in adaptation to circumstances novel alike to 

 the experience of the individual and to that of the species. 



