ADAPTATION TO ENVIRONMENT 37 



have been evolved reactions more delicate, more subtle 

 and more complex than were needed in man's primitive 

 existence. The evolved mechanism by which man 

 responds to the new elements in his environment by 

 processes of reason, invention, sentiment, moral pre- 

 cept, laws, customs and social organization, may seem 

 vastly more " elevated" and abstract than the reac- 

 tions of digestion, locomotion and " instinct," which 

 suffice for the " lower" orders. The mechanism by 

 which the more complex reactions are brought about, 

 however, is similar to that which, in its earliest form 

 as a group of specialized cells, coordinated the move- 

 ments of the Amphioxus for purposes of locomotion 

 and digestion ; in a later form as the simple brain 

 of the struggling vertebrates, gave acuteness of sight 

 and fleetness of limb to the tree-climbing species ; and, 

 as the brain of the caveman,, contributed ability to 

 fashion and to fling his arrow weapons. 



"Mind," the word we use to express the reactions 

 of this mechanism, is no phenomenon apart and dis- 

 tinct from other functions of the nervous system. In- 

 deed, mind, as we find it in the "lower walks" of life, 

 is not confined to animals. Many plants exhibit in 

 response to external stimuli protective reflexes which 

 are analogous to the nervous reflexes of man. No- 

 table among these are the drooping of the leaves of the 

 sensitive plant when it is lightly touched, and the 

 movements by which ihe Drosera and Venus 7 fly- 

 trap capture and digest their prey when they are 

 excited by the touch of an insect. It appears that 

 sensitiveness to stimuli, which is the first form of mind, 

 has been distributed in organisms, coincidentally with 



