108 MIND IN EVOLUTION CHAP. 



of the animal kingdom, the individual organism has a 

 certain power, greater or less as the case may be, of 

 effecting a similar correlation within its own lifetime. It 

 does not come into existence with all its actions prede- 

 termined in every detail by inherited structure, for we find 

 its behaviour modified as its life advances. We have seen 

 that a measure of such modification arises within the 

 sphere of " pure instinct." But to complete our account 

 of instinct we were forced to take notice of certain more 

 thorough-going modifications which could not be explained 

 in the same way. Such modifications we referred pro- 

 visionally to intelligence, meaning by intelligence the 

 power of an organism to adapt action to requirement 

 on the basis of its own experience. We have now to ask 

 what proof there is that any given adjustment is thus 

 discovered, so to say, by the individual, and is not merely 

 some subtler or less usual device of heredity. The broad 

 answer to this question is that modification in accordance 

 with the results of experience must be our main criterion. 

 When we find an animal, for example, first acting in one 

 way, and then, after experience of results, acting in 

 another, we must ascribe the change to the effect of its 

 experience. The modified action is not hereditary ; it 

 I arises in and out of the experience of the animal, and 

 / indicates that in some degree the animal can correlate its 

 ! own past experiences with its subsequent action. In this 

 correlation we have already found the generic essence of 

 intelligence, and our task will now be to describe the form 

 in which it first appears, and then to trace its further 

 evolution. In the growth of this power of correlation 

 lies the evolution of Mind. 

 2. Experience and inference. 



Physiologically considered, the effects of experience 

 upon behaviour form a special case of organic adaptability. 

 But it may be remarked here once for all that when we 

 speak of experience we shall mean a special kind of 

 experience and a special case of organic adaptability. 

 Wherever after a certain experience the organism adapts 

 itself better to a certain sort of stimulus, it has un- 

 doubtedly been modified by its experience, but it has not 



