CHAPTER III. 



INTRODUCTORY SKETCH. 



NATURAL science has shown us how the existing colouration 

 of an animal or plant can be laid hold of and modified in 

 almost infinite ways under the influence of natural or artificial 

 evolution. 



It shows us, for example, how the early pink leaf-buds have been 

 modified into attractive flowers to ensure fertilisation ; and it has 

 tracked this action through many of its details. It has explained 

 the rich hue of the bracts of Bougainvillea, in which the flowers 

 themselves are inconspicuous, and the coloured flower-stems in other 

 plants, as efforts to attract notice of the flower-frequenting insects. 

 It has explained how a blaze of colour is attained in some plants, as 

 in roses and lilies by large single flowers ; how the same effect is 

 produced by a number of small flowers brought to the same plane 

 by gradually increasing flower-stalks, as in the elderberry, or by 

 still smaller flowers clustered into a head, as in daisies and sun- 

 flowers. 



It teaches us again how fruits have become highly coloured to 

 lure fruit-eating birds and mammals, and how many flowers are 

 striped as guides to the honey-bearing nectary. 



Entering more into detail, we are enabled to see how the weird 

 walking-stick and leaf-insects have attained their remarkable pro- 

 tective resemblances, and how the East Indian leaf-butterflies are 

 enabled to deceive alike the birds that would fain devour them, and 

 the naturalist who would study them. Even the still more re- 

 markable cases of protective mimicry, in which one animal so 

 closely mimics another as to derive all the benefits that accrue to 

 its protector, are made clear. 



