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 of 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 ^'c^^re-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 t)^es 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 conmionly 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 a«/«-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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