320 THE WORLD OF LIFE 



in the struggle for existence. The former I have, I think, 

 proved to be a true cause ; the latter I reject for reasons 

 given in my Darwinism. I there give an alternative solution 

 of the problem which I still think to be fundamentally- 

 correct and which has been arrived at by Weismann and 

 others from theoretical considerations to which I may advert 

 later on. 



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Coloration of Insects 



Passing now to the order of insects which perhaps ex- 

 hibits the greatest range of colour-display in the whole of 

 the organic world — especially in the order Lepidoptera, we 

 find the difficulties in the way of a purely utilitarian solution 

 still greater. Any one who is acquainted with this order of 

 insects in its fullest development in the equatorial zone of 

 the great continents, will recognise how impossible it is to 

 give any adequate conception of its wealth of colour-decoration 

 by a mere verbal description. Yet the attempt must be 

 made in order to complete the argument I am founding 

 upon a consideration of the whole of the facts of organic . 

 coloration. 



Even in the temperate zones we have a rich display of 

 colour and marking in our exquisite little blues, our silver- : 

 spotted fritillaries, our red-admiral, our peacock, and 

 our orange-tip butterflies, and on the Continent, the two 

 swallow-tails, the Apollo butterflies, the fine Chaaxes Jason, 

 and many others. But these are absolutely as nothing i 

 compared to the wealth of colour displayed in the eastern 

 and western tropics, where the average size is from two to j 

 three times ours, and the numbers, both in species and i 

 individuals at least ten times as great. Not only is there 

 every tint of red, yellow, blue and green, on ground-colours 

 of black or white and various shades of brown or buff, but 

 we find the most vivid metallic blues or silky yellows 

 covering a large portion of the wing-surface or displayed 

 in a variety of patterns that is almost bewildering in its 

 diversity and beauty. 



As a few examples, the Callithea sapphira of the Amazon 

 is of a soft, celestial blue that the finest lobelia or gentian 

 cannot surpass. The grand Omithoptera Amphrisius and its 



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