38 MAN AN ADAPTIVE MECHANISM 



mobility. To stationary plants, except in the case 

 of the insectivorous forms, such irritability could be of 

 little benefit to the species ; but to the pursuing and 

 pursued organisms it is of great advantage. In his 

 treatise on climbing plants Darwin remarks that it has 

 sometimes been asserted that plants are distinguished 

 from animals by their lack of power of motion, and he 

 succinctly adds : "It should rather be said that plants 

 acquire and display this power only where it is of some 

 advantage to them." 



The test of utility may be applied to internal proc- 

 esses as well as to external manifestations in custom 

 and social forms of man's peculiar mode of adaptation 

 by nervous reactions. On this basis man's claim to 

 a superior place among animals depends less upon 

 different reactions than upon a greater number of re- 

 actions as compared with the reactions of "lower" 

 animals. Ability to respond adaptively to more ele- 

 ments in the environment gives a larger dominion, 

 that is all. 



The same measure applies within the human species, 

 the number of nervous reactions of the artist, the 

 financier, the statesman, the scientist, being invariably 

 greater than the reactions of the stolid savage. That 

 man alone of all animals should have achieved the 

 degree of versatility sufficient for such advance is no 

 more remarkable than that the elephant should have 

 evolved a larger trunk and tusks than the boar ; that 

 the legs of the deer should be fleeter than those of the 

 ox ; that the wings of the swallow should outfly those 

 of the bat. Each organism, in evolving the combina- 

 tion of characters commensurate with safety in its 



