The Making of Species 



Leaf-shape and general dead-leaf colour-scheme 

 are necessary for this illusion. But are these 

 following things necessary ? namely, an extra- 

 ordinarily faithful representation of mid-rib and 

 lateral veins, even to faint microscopically-tapering 

 vein tips ; a perfect short petiole produced by the 

 apposed ' tails ' of the hind-wings ; a conceal- 

 ment of the head of the butterfly so that it shall 

 not mar the outlines of the lateral margin of the 

 leaf ; and finally, delicate little flakes of purplish 

 or yellowish brown to mimic spots of decay and 

 fungus-attacked spots in the leaf ! And, as culmin- 

 ation, a tiny circular clear spot in the fore-wings 

 (terminal part of the leaf) which shall represent 

 a worm-eaten hole, or a piercing of the dry leaf 

 by flying splinter, or the complete decay of a 

 little spot due to fungus growth ! A general 

 and sufficient seeming of a dead leaf, object of no 

 bird's active interest, yes, but not a dead leaf 

 modelled with the fidelity of the waxworkers in 

 the modern natural history museums. When 

 natural selection has got Kallima along to that 

 highly desirable stage when it was so like a dead 

 leaf in general seeming that every bird sweeping 

 by saw it only as a brown leaf clinging pre- 

 cariously to a half-stripped branch, it was natural 

 selection's bounden duty, in conformance to its 

 obligations to its makers, to stop the further 

 modelling of Kallima and just hold it up to its 

 hardly won advantage. But what happens ? 



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