THE EVOLUTION OF SEX 53 



like a dancing elf. But one suitor is not 

 enough. The female attracts a levee. In 

 polite rivalry her devotees form a circle and 

 await the coquette's choice. In the two sexes, 

 Emery says, the colour of the light is identical, 

 and the intensity seems much the same, 

 though the love-light of the female is more 

 restricted. The most noteworthy difference 

 is that the luminous rhythm of the male is 

 more rapid, with briefer flashes ; while that 

 of the female is more prolonged, with longer 

 intervals, and more tremulous illumined sym- 

 bols of the contrast between the sexes. The 

 female Luciola sits surrounded by her suitors ; 

 flashes of light come and go ; finally a choice 

 is made and the party breaks up. Whatever 

 the luminescence may mean physiologically 

 in the constitution of the insect, it seems to be 

 a love-signal between the sexes. 



It is confessedly very difficult to prove 

 that the courtships of animals are associated 

 with emotions analogous to ours, but in many 

 cases there are visible manifestations similar 

 to those which accompany emotion in our- 

 selves. To refuse to believe that the exuber- 

 ant song of birds is associated with joyousness 

 is a sternness of scepticism for which we are 

 not prepared. In many cases, apart from 

 any immediate gratification of sexual desire, 

 the mates look as if they liked one another. 

 They pine when they are separated; and if 

 they are not pleased to be reunited, they 

 have an extraordinary power of behaving and 

 looking as if they were. 



CO-OPERATION OF THE SEXES. Yet a higher 

 grade is illustrated by those animals which 



