14 Colouration in Animals and Plants. 



dots must be made, and so on, the result not being development 

 along a certain line, but an infinity of interlacing curves. The tree 

 of life is not like this. It branches ever outwards and onwards. 

 The eyes of the Argus pheasant and peacock have been formed by 

 the accumulation, through long generations, of more and more 

 perfect forms ; the mechanism of the eye and hand has arisen by 

 the gradual accumulation of more and more perfect forms, and these 

 processes have been continued along definite lines. 



If we grant memory we eliminate this hap-hazard natural 

 selection. We see how a being that has once begun to perform a 

 certain action will soon perform it automatically, and when its habits 

 are confirmed its descendants will more readily work in this direction 

 than any other, and so specialisation may arise. 



To take the cases of protective resemblance and mimicry. 

 Darwin and Wallace have to start with a form something like the 

 body mimicked, without giving any idea as to how that resemblance 

 could arise. But with this key of memory we can open nature's 

 treasure house much more fully. Look, for instance, at nocturnal 

 insects ; and one need not go further than the beetles (Blatta) in the 

 kitchen, to see that they have a sense of need, and use it. Suddenly 

 turn up the gas, and see the hurried scamper of the alarmed crowd. 

 They are perfectly aware that danger is at hand. Equally well do 

 they feel that safety lies in concealment ; and while all the foraging 

 party on the white floor are scuttling away into dark corners, the 

 fortunate dweller on the hearth stands motionless beneath the 

 shadow of the fire-irons ; a picture of keen, intense excitement, with 

 antenna) quivering with alertness. On the clean floor a careless 

 girl has dropped a piece of flat coal, and on it beetles stand 

 rigidly. They are as conscious as we are that the shadow, and the 

 colour of the coal afford concealment, and we cannot doubt that they 

 have become black from their sense of the protection they thus 

 enjoy. They do not say, as Tom, the Water Baby, says, " I must 

 be clean," but they know they must be black, and black they are. 



There is, then, clearly an effort to assimilate in hue to their 

 surroundings, and the whole question is comparatively clear. 



Mr. Wallace, in commenting upon the butterfly (Papilio nireus) 

 which, at the Cape, in its chrysalis state, copies the bright hues of 

 the vegetation upon which it passes its dormant phase says that 

 this is a kind of natural colour photography ; thus reducing the 

 action to a mere physical one. We might as well say the dun coat 



