ORIGIN OF SONG 165 



been an ever-widening one ; and as with their 

 multiplication, irregularities and delays in 

 mating, arising from the similarity of the calls, 

 would have increased in frequency, so a distinc- 

 tive call, which would have tended to minimise 

 these risks, would have come to possess 

 biological value. 



Here we have a theory of origin, but origin 

 of what ? Of certain characteristics of song — 

 nothing more ; and therefore to suppose that it 

 furnishes a complete explanation, which satisfies 

 all the requirements of scientific logic, of so 

 wonderful an intonation as that, for example, of 

 the Marsh-Warbler, or that no other relation- 

 ships, except that of the territory, enter into the 

 total emotional complex, simplifying here or 

 elaborating there to meet the exigencies of 

 diverse circumstances — to suppose this would be 

 foolish. That there are many relationships 

 which even to-day are leading to modifications 

 in important particulars, but which at the 

 present time are beyond our cognisance, of this 

 there can be no doubt. 



There is one process by which song may 

 have attained a fuller development, and which 

 would account in some measure for the elabora- 

 tion, inexplicable merely in terms of " recogni- 

 tion." It is this : the effect of the sexual call 

 upon the female cannot well be neutral, it must 

 be either pleasurable or the reverse — it must, that 

 is to say, be accompanied by some suggestiveness, 

 and by suggestion I mean the arousing of some 

 emotion akin to that of the male ; and if there 



