144 RELATION OF SONG TO THE TERRITORY 



more particularly by one remarkable case, the 

 case of the Cuckoo. The male, after having 

 established himself, utters his call persistently 

 from the day of arrival until approximately the 

 middle of June ; but, in contrast with the 

 large majority of species, the female has a 

 characteristic call which she, too, utters at 

 frequent intervals. The female is polyandrous 

 and has a sphere of influence embracing the 

 territories of a number of males ; she wanders 

 from place to place, is often silent, and not 

 unfrequently is engaged in dealing with her egg 

 or in searching for a nest in which to deposit it, 

 and therefore she is not always in touch with a 

 male, still less with any particular one. Now 

 there is much evidence to show that the 

 discharge of the sexual function amongst birds 

 is subject to control, and that this control 

 operates through the female — through her 

 physiological state becoming susceptible to 

 stimulation only at certain periods. So that we 

 have these considerations, that the female is 

 polyandrous, that she has a territory distinct 

 from that of the male, and that her sexual 

 impulse is periodical ; and the further considera- 

 tion that the impulse, since it is periodical, is of 

 limited duration and must receive immediate 

 satisfaction. Such being the circumstances of 

 the case, would the voice of the male serve to 

 insure the union of the sexes at the appropriate 

 moment? Well, the fact that she is poly- 

 androus implies that every male in her sphere of 

 influence is not always capable of satisfying her 



