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 ? 
46 , 
