w 



NATURAL SELECTION 



specimen of inductive reasoning. The facts al- 

 ready cited are quite enough to sustain the gen- 

 eral conclusion that the colours of animals are 

 in the main determined by the exigencies of 

 the struggle for existence. Where it is for the 

 advantage of an animal to be concealed, as in 

 the great majority of cases, its colour, whether 

 brilliant or sombre, is such as to protect it. 

 But where the animal is otherwise adequately 

 protected, — either by its peculiar habits, by a 

 sting, a disgusting odour or taste, or a hard 

 carapace, — and where it is not needful for it 

 to be hidden from the prey upon which it feeds, 

 then there is usually no reference to protection 

 in the colour of the animal. In some of these 

 cases, however, a very conspicuous colouring 

 becomes protective — as in the case of the jet- 

 black toad which Mr. Darwin saw in La Plata, 

 which emitted a poisonous secretion, and which, 

 when crawling over the sandy plain, could not 

 fail to be recognized by every passing creature 

 as an object to be avoided. 



In many cases the gorgeous tints of the 

 otherwise protected male animal are due to 

 what is called " sexual selection," — to the con- 

 tinual selection of the more beautiful males by 

 the females. To this cause is due the magni- 

 ficent plumage of the male bird of paradise ; 

 and Mr. Darwin would similarly explain the 

 brilliant colours of many male butterflies. In 

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