50 NATURAL SELECTION in 



tions, when not accompanied by others that were unfavourable, 

 would certainly survive. At one time a little step might be 

 made in this direction, at another time in that a change of 

 conditions might sometimes render useless that which it had 

 taken ages to produce great and sudden physical modifica- 

 tions might often produce the extinction of a race just as it 

 was approaching perfection, and a hundred checks of which 

 we can know nothing may have retarded the progress towards 

 perfect adaptation ; so that we can hardly wonder at there 

 being so few cases in which a completely successful result has 

 been attained as shown by the abundance and wide diffusion 

 of the creatures so protected. 



Objection that Colour, as being dangerous, should not exist in 

 Nature 



It is as well here to reply to an objection that will no 

 doubt occur to many readers that if concealment is so useful 

 to all animals, and so easily brought about by variation and 

 survival of the fittest, there ought to be no conspicuously- 

 coloured creatures; and they will perhaps ask how we 

 account for the brilliant birds, and painted snakes, and 

 gorgeous insects that occur abundantly all over the world. 

 It will be advisable to answer this question rather fully, in 

 order that we may be prepared to understand the phenomena 

 of " mimicry," which it is the special object of this chapter to 

 illustrate and explain. 



The slightest observation of the life of animals will show 

 us that they escape from their enemies and obtain their food 

 in an infinite number of ways, and that their varied habits 

 and instincts are in every case adapted to the conditions of 

 their existence. The porcupine and the hedgehog have a 

 defensive armour that saves them from the attacks of most 

 animals. The tortoise is not injured by the conspicuous 

 colours of his shell, because that shell is in most cases an 

 effectual protection to him. The skunks of North America 

 find safety in their power of emitting an unbearably offensive 

 odour ; the beaver in its aquatic habits and solidly constructed 

 abode. In some cases the chief danger to an animal occurs 

 at one particular period of its existence, and if that is guarded 

 against its numbers can easily be maintained. This is the 



