xiv PROOFS OF ORGANISING MIND 303 



of metallic brilliancy fully equal (probably superior) to that 

 of birds, but they possess also in a few cases and in distinct 

 families, changeable opalescent hues, in which a pure crimson, 

 or blue, or yellow pigment, as the incidence of light varies, 

 changes into an intense luminous opalescence, sometimes 

 resembling a brilliant phosphorescence more than any 

 metallic or mineral lustre, as described in the next chapter. 



And what renders the wealth of coloration thus 

 produced the more remarkable is, that, unlike the feathers 

 of birds, the special organs upon which these colours and 

 patterns are displayed are not functionally essential to the 

 insect's existence. They have all the appearance of an 

 added superstructure to the wing, because in this way a 

 greater and more brilliant display of colour could be produced 

 than even upon the exquisite plumage of birds. It is true 

 that in some cases, these scales have been modified into 

 scent-glands in the males of some butterflies, and perhaps in 

 the females of some moths, but otherwise they are the 

 vehicles of colour alone ; and though the diversity of tint 

 and pattern is undoubtedly useful in a variety of ways to 

 the insects themselves, yet it is so almost wholly in relation 

 to higher animals and not to their own kind, as I have 

 already explained in Chapter IX. It is generally admitted 

 that insects with compound eyes possess imperfect vision, 

 and their actions seem to show that they take little notice 

 of distant objects, except of lights at night, and only perceive 

 distinctly what is a few inches or a few feet from them ; 

 while there is no proof that they recognise what we term 

 colour unless as a greater or less amount of light. 



But as regards the effect of the shading and coloration 

 of insects upon the higher animals, who are almost always 

 their enemies, there is ample evidence. Almost all students 

 of the subject admit that the markings and tints of insects 

 often resemble their environment in a remarkable manner, 

 and that this resemblance is protective. The eye-like 

 markings, either on the upper or under surfaces, are often 

 seen to be imitations of the eyes of vertebrates, when the 

 insect is at rest, and this also is protective. The brilliant 

 metallic or phosphorescent colours on the wings of butterflies 

 may serve to distract enemies from attacking a vital part, or, 



