possesses characteristic actual contours and internal details; these, if the 

 butterfly is to elude the eyes of its enemies, must be made as inconspicuous 

 as possible. How should this be done — how has Nature done it? By the 

 introduction of sham details, of such plainness, and so bestowed on the but- 

 terfly's surface, as to eclipse and neutralize the real but faintlier showing 

 details and contours. The stronger the pattern appears, the dimmer appear 

 the forms and outlines oj its wearer — as the reader has been shown. Patterns, 

 then, in the obliterative costumes of butterflies, are so placed as fundamentally 

 to thwart the conspicuousness of their wearers' forms; and, at the same time, 

 the resultant effect of these intrinsically ' dazzling' and 'obliterative' mark- 

 ings, under the normal conditions, is of perfect picture-pattern. These two 

 principles, in fact — if indeed they can be called two — work in practically 

 inseparable combination and cooperation. Thus is achieved for butterflies 

 the highest possible degree of average inconspicuousness — as, indeed, it is 

 achieved for the many other types of animal we have considered. Only, the 

 case of butterflies is simpler, because the third great principle, obliterative 

 shading, being confined to their bodies, plays, as to area, a comparatively small 

 part in their disguisement. 



Let us look at a few concrete examples of these more subtile phases of 

 'dazzling '-coloration. There can be no doubt that the entire arrangement 

 of markings on the most brilliantly and elaborately patterned of butterflies 

 is hostile to the conspicuousness of the insect's general form: let us then con- 

 sider some of the details of this 'eclipsing '-system. Among the markings 

 whose function is the masking and 'breaking' of external contours, two are 

 especially notable. One is the diagonal cross-band at or very near the end 

 of each fore- wing, which 'cuts off' a bigger or smaller tip, thus marring 

 the characteristic outline; the other is a band, or more commonly a series of 

 spots, following more or less closely the real contour, in just the right position 

 to neutralize the real contour's conspicuousness by distracting the eye's atten- 

 tion to the aw^-contour's vivider details, which serve as background-pictures, 

 and are as a rule supported in this effect by other and more varied internal 



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