98 The Study of Animal Life PART i 



of their bright plumage ; with flowers, bright pods, and 

 shining shells, the bower- birds decorate tents of love for 

 their honeymoon. The mammals woo chiefly by force ; the 

 birds are often moved to love by beauty, and mates often 

 live in prolonged partnership with mutual delight and help- 

 fulness. Sixty years before Darwin elaborated his theory of 

 sexual selection, according to which males have grown more 

 attractive because the most captivating suitors were most 

 successful in love, the ornithologist Bechstein noted how the 

 female canary or finch would choose the best singer among 

 a crowd of suitors ; and there seems some reason to believe 

 that the female's choice of the most musical or the most 

 handsome has been a factor in progress. Wallace, on the 

 contrary, maintains that the females are plainly dressed 

 because of the fate which has befallen the conspicuous during 

 incubation, and surely they must thus be handicapped. To 

 others it seems more natural to admit that there is truth in 

 both Darwin's and Wallace's conclusions, but to regard the 

 males as stronger, handsomer, or more musical simply 

 because they are males, of more active constitutional habit 

 than their mates. To this view Mr. Wallace himself inclines. 



Compared with the lion's thunder, the elephant's trum- 

 peting, or the stag's resonant bass, and the might which 

 lies behind these, or with the warble of the nightingale, 

 the carol of the thrush, the lark's blithe lay, or the mocking- 

 bird's nocturne, and the emotional wealth which these ex- 

 press, the challenges and calls of love among other classes 

 of animals are apt to seem lacking in force or beauty. But 

 our human judgment affords no sure criterion. The frogs 

 and newts, which lead on an average a somewhat sluggish 

 life, wake up at pairing time, and croak according to their 

 strength. The males are often furnished with two reson- 

 ating sacs at the back of the mouth, and how they can croak 

 dwellers by marsh -land know ; the North American bull- 

 frog bellows by himself, and the South American tree-frogs 

 hold a concert in the branches. 



Of the mating of fishes we know little, but there are some 

 well-known cases alike of display and of tournament. The 

 stickleback fights with his rivals, leads his mate to 



