The Making of Species 
Nature having thus visually unsubstantialized 
the bodies of animals, so that, if seen at all, they 
look flat and ghostly, does not stop there. From 
solid-shaded bodies they have been converted, 
as it were, into flat cards or canvases, and, to 
complete the illusion of obliteration, pictures 
of the background—veritable pictures of the 
more or less distant landscape—have been 
painted on their canvases! Such in effect are 
the elaborate ‘markings of field and forest 
birds.” 
Again he writes: “Brilliantly changeable or 
metallic colours are usually supposed to make 
the birds that wear them conspicuous, but nothing 
could be further from the truth. Iridescence is, 
indeed, one of the strongest factors of conceal- 
ment. The quicksilver-like intershifting of many 
lights and colours, which the slightest motion 
generates on an iridescent surface, like the back 
of a bird or the wing of a butterfly, destroys the 
visibility of that wing or back as such and causes 
it to blend inextricably with the gleaming and 
scintillating labyrinthine-shadowed world of wind- 
swayed leaves and flowers.” 
According to Thayer, the skunk, which for 
years has been an important item of the stock-in- 
trade of the advocates of the theory of warning 
colouration, is an excellent example of obliterative 
colouring, since its enemies are supposed to mis- 
take for the sky-line the line of junction between 
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