414 THE WONDER OF LIFE 



cold-blooded fishes and newts have their love-play. Finest 

 and most familiar is the musical appeal of many birds. 



Thousands of interesting facts are known as to visible 

 behaviour, but it is difficult to judge of the inward spirit. 

 We must not be recklessly generous, nor materialistically 

 sceptical. The whole life is one, and while we know that 

 internal secretions or hormones, liberated at the breeding 

 season and pervading the whole body, influence the brain 

 and the whole nervous system, and the circulation of the 

 blood and its composition, we are not on that account to 

 suppose that the bird on the bough is emotionless, like a 

 musical box. We must not read too much into the displays, 

 for the suitors are, as it were, sex-intoxicated, expressing 

 their ardour instinctively and with abandon, rather than 

 with deliberation or strategy, but we must not think of 

 them too cheaply, as if they expressed lust only, and no 

 love. 



As to the evolutionary importance of the courtship 

 behaviour, there is need at present for a critical revision of 

 the data. The late Alfred Russel Wallace always insisted, 

 thus differing from Darwin, that there was little convincing 

 evidence that the female bird chooses her partner, or chooses 

 him because of any particular excellence in colour or 

 plumage, agility or musical talent ; but some good ornithol- 

 ogists bring forward circumstantial cases of unattractive 

 male birds being left unmated. More facts are needed. 

 While Darwin seemed sometimes to credit the females with 

 a high degree of taste or aesthetic fastidiousness, he was 

 probably on safer ground when he wrote : ' It is not probable 

 that she consciously deliberates ; but she is most excited 

 or attracted by the most beautiful or melodious or gallant 

 males '. The probability is that the female surrenders 



