ii] BATESIAN AND MULLERIAN 15 



generation has to learn afresh from experience what is 

 pleasant to eat and what is not. They will try all 

 things and hold fast to that which is good. They will 

 learn to associate the gay colours of the Heliconine and 

 the Ithomiine with an evil taste 1 and they will thence- 

 forward avoid butterflies which advertise themselves 

 by means of these particular colour combinations. But 

 in a locality where there are many models, each with 

 a different pattern and colour complex, each will have 

 to be tested separately before the unpalatableness of 

 each is realised. If for example a thousand young 

 birds started their education on a population of 

 butterflies in which there were five disagreeable species, 

 each with a distinct warning pattern, it is clear that 

 one thousand of each would devote their lives to the 

 education of these birds, or five thousand butterflies 

 in all 2 . But if these five species, instead of shewing 

 five distinct warning patterns, all displayed the same 

 one it is evident that the education of the birds would 

 be accomplished at the price of but one thousand 

 butterfly existences instead of five. Even if one of 

 the five species were far more abundant than the 

 others it would yet be to its advantage that the other 

 four should exhibit the same warning pattern. Even 

 though the losses were distributed pro rata the more 

 abundant species would profit to some extent. For 



1 In attributing this quality to the butterflies in question I am 

 merely stating what is held by the supporters of the mimicry theory. 

 I know of scarcely any evidence either for or against the supposition. 



2 It is assumed that the intelligence of the birds is such that they 

 can learn a pattern after a single disagreeable experience of it. 



