CONCLUSION 71 



any particular condition in the environment, 

 and hence for a time the bird oscillates between 

 two modes of behaviom' — between that one 

 organised by frequent repetition and that one 

 determined by the functioning of this new 

 disposition. 



To look at the matter broadly, it is scarcely 

 likely that so definite a mode of behaviour would 

 recur with such regularity, generation after 

 generation, in the individuals belonging to so 

 many widely divergent forms, if it had no root 

 in the inborn constitution of the bird. But the 

 law of habit formation has its part to play also. 

 By itself it is inadequate ; yet it probably does 

 assist very materially in adding still greater 

 definition, and it probably is responsible in a 

 large measure for determining the limits of 

 the territory according to the conditions of 

 existence of the species — thus the Falcon 

 seeks its prey over wide tracts of land, and, 

 by hunting over certain ground repeatedly, 

 establishes a routine, which broadly fixes the 

 area occupied ; the Woodpecker cannot find 

 food upon every tree, and every forest does 

 not contain the necessary trees, and therefore 

 the bird regulates its flight according to the 

 position of the trees ; and the Warbler, finding 

 food close at hand, does not need to travel 

 far, and the area it occupies is consequently 

 small. 



So that the most likely solution of the 

 problem will be found in a combination of our 

 second and third propositions ; that is to say, in 



F 2 



