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biologists tell us there is necessary a certain education of the 

 hostile individuals. The creatures have to learn the meaning 

 of the coloration; and this learning involves profiting by 

 experience. . . . Here is as distinctly a mental process in- 

 volved as any one might cite. . . . The action of natural 

 selection, I may add for completeness, secures the survival of 

 the insects so coloured, seeing that being warned, their 

 enemies let them alone. The possibility of the evolution of 

 the definite coloration turns, in fact, upon this series of 

 psychological processes." 



Here the psychic endowment of the enemy is seen to be a 

 factor in the evolution of the prey ; and it may of course be 

 added that to ensure for the warning colour its full effect, it 

 is necessary that its owner should possess the appropriate 

 habits. Similar instances will at once occur to every field 

 naturalist. Protectively-coloured insects instinctively seek 

 corresponding surroundings. An interesting case of this is 

 the fact which now seems fairly well established of yellow and 

 white butterflies selecting for resting-places the neighbourhood 

 of leaves or flowers of similar colour. Dr. Longstaff's excel- 

 lent plate, drawn from nature, of the resting habit of Eronia 

 cleodora will occur to many of you. I ought to apologise for 

 dwelling on so familiar a topic, but the fact really requires 

 emphasising that the raw material of selection is neither 

 purely physical nor purely psychical, but a complex of the 

 two. The admission of this fact, so patent to every observer 

 of insects, has important consequences. For as soon as we 

 can recognise a rudimentary form of mentality — the gaining 

 of a definite result by the method of trial and error — we have 

 a basis for habit, for memory, and eventually for the higher 

 psychological faculties. In the instances that I have men- 

 tioned of the correlation of appropriate habits with a pro- 

 tective colouring, there is no reason to suppose the presence 

 of anything like conscious accommodation ; the actions in 

 question are no doubt instinctive in the strictest sense. But 

 quite low down in the animal scale, and even, I think it will 

 be conceded, among the insects, we get indications of " residual 

 processes left by actual experiences " leading to what can only 

 be called memory. These processes, of undoubted utility, may 



