ESTHETIC FEELING IN BIRDS. 661 



have been carried out to a very great extent. But all such divergent 

 fancies must themselves tend to become distinctly fixed for purposes 

 of specific identification ; and we find as a matter of fact that each 

 species does readily recognize its mates, even when the differences be- 

 tween closely allied species are only very slight. 



Now, this special hereditary liking for a particular form and type 

 will not interfere with the general love for color, brilliancy, sweet 

 tones, and perfumes. Accordingly, wherever the circumstances which 

 give rise to a taste for these sense-stimulants exist, it would naturally 

 follow that the taste would help to determine the choice of mates. 

 But, again, as Mr. Wallace has fully shown, the most vigorous indi- 

 viduals would usually possess the most highly developed ornaments, 

 the brightest colors, the largest scent-glands, and the loudest or most 

 musical voices. Hence the very animals most likely to be sexually 

 selected are also, on the average, those most likely to be naturally 

 selected. Yet sexual selection really differs from natural selection, in 

 that it gives a special direction to the ornamentation. For example, 

 one can hardly believe that mere masculine vigor will account for the 

 gorgeous and positively inconvenient plumage of the bird-of -paradise, 

 nor for the exquisite coloring of the peacock, nor for the extremely 

 ungainly air-bladders of many insects. It is quite easy to conceive 

 that the general vigor implied by the possession of these extended or- 

 namental adjuncts may have helped their possessors in the general 

 struggle for life ; but it is hardly possible to believe that they could 

 have reached their present definite development without the aid of 

 sexual selection. In short, where an ornament, or what seemed to any 

 particular individual an ornament, proved hurtful to the race, it would 

 be eliminated by natural selection ; but where it proved neutral it 

 would be spared, and if it coincided with advantageous qualities it 

 would be further developed. Yet, even if only neutral, sexual selec- 

 tion alone would give it an extra chance, and, as it would doubtless be 

 correlated on the one hand with certain special tastes and habits, and on 

 the other hand with certain slight modifications of structure, it would 

 doubtless succeed on an average of cases in producing a new species. 



The familiar facts of human beauty will probably serve to make 

 this reconciliation of the conflicting views a little clearer. Man of 

 course admires in the abstract bright colors, brilliancy, musical notes, 

 graceful curves, and symmetrical form. But, as applied to the human 

 face and figure, he admires these in certain special and typical arrange- 

 ments. Thus, while our general love for color leads us to prize golden 

 hair, we do not like a sallow complexion ; while it leads us to see 

 beauty in rosy cheeks and red lips, which are signs of a healthy circu- 

 lation, we do not admire the same redness in the nose, where it is 

 usually a result of dyspepsia or dissipated habits, either of which is 

 bad for the race at large. Again, though we admire pearly teeth, 

 clear eyes, and a white skin, all of which are obviously the external 



