reader will readily perceive how well adapted butterflies are to profit by this 

 factor of disguise. Though prevalent in almost all the main butterfly groups 

 already named, and often playing a part in minute picture-patterns, lustrous 

 changeable color reaches its highest development among aerial species, and 

 especially those of the skyey over-realm of tropical woods (Chapter XIX, pp. 

 107-108). Its range of tint is chiefly from reddish purple to golden green — a 

 scale which includes all the hues of open sky and sunlit foliage, and glowing 

 interstitial shadow. Sometimes, for instance, as in the case of some of the 

 big South American Morphos, almost the entire upper surface is covered with 

 immaculate iridescent color. These glittering blue butterflies are for the 

 most part highly aerial, and their color works like that of the peacock's neck 

 (see Plate I), matching, in flashes, sky and sky-lit foliage, etc. Some of them, 

 on the other hand, are also much given to perching low down in the forest, 

 and here their vivid blue, in cooperation with their brown, picture-patterned 

 undersides, achieves 'dazzling coloration,' of the active, metamorphic sort. 

 The bright color of such species is apt to be less iridescent and shiny than 

 fixedly lustrous, shifting somewhat in minor tints and in intensity, but in 

 main effect staying always blue, whereas the blue of the more aerial and tree- 

 top-haunting Morpho anaxibia, for instance, shifts to purple and to green in 

 vivid play and interplay of keen metallic tints. The 'dazzling' effect pro- 

 duced by some of these Morphos' costumes is often most pronounced. Imag- 

 ine watching such a butterfly as it sails along through the brown aisles of a 

 South American jungle. Its broad, immaculate blue wings look almost lu- 

 minous in their glaring brightness, and the eye follows them easily and fasci- 

 natedly along their course. Suddenly the butterfly alights, folding its wings 

 sharply together, and — is no more. The eye must be well trained indeed to 

 recover from its ' dazzlement ' in time to mark the insect down exactly. It is 

 like trying to see clearly after staring at the sun. More than this, the abrupt- 

 ness of the metamorphosis, the instantaneous eclipse of the bright thing which 

 the eye has been following, has in itself a very confusing effect. The butter- 

 fly sits motionless, and will not stir its folded, dark-brown wings, covered with 



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