302 COLOUR IN NATURE chap. 



which they live, that they can only be distinguished 

 with difficulty. If the enemies of such species are 

 psychologically similar to ourselves, the colouring 

 must render them less conspicuous to these enemies, 

 and must thus be protective. Therefore it may be said 

 that, however the colour in these cases first arose, it 

 must always have been, other things being equal, 

 useful to the species ; therefore the forms displaying 

 these colours would tend to persist, the others would 

 tend to be eliminated ; therefore we may say that the 

 colour arose by Natural Selection, which weeded out 

 all those not possessing it. 



This is in essence the explanation of colour 

 phenomena given by a great number of naturalists at 

 the present time. Colour they say is originally non- 

 significant, a result of the chemical or physical 

 properties of substances ; its appearance in the super- 

 ficial tissues may render the organism better fitted 

 to survive in the struggle for existence, and therefore 

 is encouraged and maintained by Natural Selection. 

 The various types of coloration presumed to be of 

 use have been classified under the headings of 

 Protective Resemblance, Mimicry, Warning Colours, 

 and so on ; their use is supposed to be to protect 

 the organism from its enemies, to enable it to steal 

 unperceived on its prey, or to warn its enemies that 

 it is unpalatable or dangerous and must be avoided. 

 Beside these, however, there is another series of 

 colours to be considered. We have already seen 

 that in birds the males are frequently far more 

 brilliantly coloured and ornamented than the females. 

 As these colours do not fall into any of the divisions 

 already mentioned, many naturalists have adopted 



