REFLEXES, INSTINCT, AND REASON 443 



individuals as there is with regard to other characters of the 

 species. Some power of choice is found in almost every opera- 

 tion of instinct. Even the most machinelike instinct shows 

 some degree of adaptability to new conditions. On the other 

 hand, in no animal does reason show entire freedom from 

 automatism or reflex action. "The fundamental identity of 

 instinct with intelligence/ 7 says an able investigator, "is shown 

 in their dependence upon the same structural mechanism (the 

 brain and nerves), and in their responsive adaptability/ 7 



FIG. 276. A wild duck, Aythya, family; male, female, and prsecocial young. 



Reason or intellect, as distinguished from instinct, is the 

 choice, more or less conscious, among responses to external 

 impressions. Its basis, like that of instinct, is in reflex action. 

 Its operations, often repeated, become similarly reflex by 

 repetition, and are known as habit. A habit is a voluntary 

 action repeated until it becomes reflex. It is essentially like 

 instinct in all its manifestations. The only evident difference 

 is in its origin. Instinct is inherited. Habit is the reaction 

 produced within the individual by its own repeated actions. 

 In the varied relations of life the pure reflex action becomes 

 inadequate. The sensorium is offered a choice of responses. 

 To choose one and to reject the others is the function of intellect^ 

 or reason. While its excessive development in man obscures its 

 close relation to instinct, both shade off by degrees into reflex 



