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 



1 86 



