28 CONTROLLED NATURAL SELECTION 



be purposely conspicuous, as it cannot be 

 indifferent. 



Yellow. The primary colour, yellow, is a 

 very rare environment for animals, and so it 

 is very rarely used protectively. A few insects 

 which fly in the autumn are yellow, in harmony 

 with the yellow autumnal foliage. Sunlight 

 penetrating young green foliage is not a pure 

 colour but yellow-green ; this colour is found 

 on the breasts of a number of birds, the 

 Willow Wren (Phylloscopus trochilus) for in- 

 stance ; compare this with the yellow bar in 

 the Goldfinch's (Carduelis elegans) wing, and 

 with the yellow of the male Golden Oriole. 



Red. Above all others, animals coloured 

 red are the most conspicuous in Nature, 

 because it is never found in the surroundings. 

 The rising and setting sun sometimes colours 

 all things red, animals as well as their sur- 

 roimdings. Thayer is of opinion that some 

 scarlet animals, Flamingoes (Phoenicopterus 

 ruber} for instance, are coloured thus to 

 render them invisible against the red of the 

 setting sun ; that which has already been said 

 about sky protections, under White and Blue, 

 also applies to Red ; a red animal against the 

 setting sun, by contrast, looks not red but 

 black. 



