282 Colour and the Struggle for Life 



enthusiasm at the brilliancy of the hypothesis and its caution in 

 acceptance without full confirmation : 



" Bates was quite right ; you are the man to apply to in a 

 difficulty. I never heard anything more ingenious than your 

 suggestion, and I hope you may be able to prove it true. That is 

 a splendid fact about the white moths 1 ; it warms one's very blood to 

 see a theory thus almost proved to be true." 



Two years later the hypothesis was proved to hold for caterpillars 

 of many kinds by J. Jenner Weir and A. G. Butler, whose observa- 

 tions have since been abundantly confirmed by many naturalists. 

 Darwin wrote to Weir, May 13, 1869 : "Your verification of Wallace's 

 suggestion seems to me to amount to quite a discovery 2 ." 



Recognition or Episematic Characters. 



This principle does not appear to have been in any way foreseen 

 by Darwin, although he draws special attention to several elements 

 of pattern which would now be interpreted by many naturalists as 

 episemes. He believed that the markings in question interfered with 

 the cryptic effect, and came to the conclusion that, even when 

 common to both sexes, they "are the result of sexual selection 

 primarily applied to the male 3 ." The most familiar of all recognition 

 characters was carefully explained by him, although here too ex- 

 plained as an ornamental feature now equally transmitted to both 

 sexes : " The hare on her form is a familiar instance of concealment 

 through colour ; yet this principle partly fails in a closely-allied 

 species, the rabbit, for when running to its burrow, it is made 

 conspicuous to the sportsman, and no doubt to all beasts of prey, by 

 its upturned white tail 4 ." 



The analogous episematic use of the bright colours of flowers 

 to attract insects for effecting cross-fertilisation and of fruits to 

 attract vertebrates for effecting dispersal is very clearly explained 

 in the Origin 5 . 



It is not, at this point, necessary to treat sematic characters at 

 any greater length. They will form the subject of a large part of the 

 following section, where the models of Batesian (Pseudaposematic) 

 mimicry are considered as well as the Mullerian (Synaposematic) 

 combinations of Warning Colours. 



1 A single white moth which was rejected by young turkeys, while other moths were 

 greedily devoured : Natural Selection, 1875, p. 78. 



2 More Letters, n. p. 71 (footnote). 3 Descent of Man, p. 544. 

 4 Descent of Man, p. 542. 



8 Ed. 1872, p. 1(51. For a good example of Darwin's caution in dealing with exceptions 

 see the allusion to brightly coloured fruit in More Letters, n. p. 348. 



