372 THE POPULAR SCIENCE MONTHLY. 



designate myself by such a periphrasis), is far more interested in the 

 modifications which feathers undergo, after they have become feathers, 

 than in those which they undergo before reaching that stage of their 

 development. For the infinite variety of coloring, the exquisite tones 

 of metallic sheen, the graceful arrangements of crests, tufts, plumes, and 

 lappets, which render birds such conspicuous objects in our museums 

 or gardens, are all of them due to the pigments or shapes of feathers, 

 and all of them have apparently been produced by the voluntary choice 

 of beautiful mates among the birds themselves. 



The modifications of feathers thus originated form, of course, a clew 

 to the tastes of the various birds which possess them; because each 

 species will naturally select such mates as best satisfy its ideas of the 

 beautiful, and so will transmit the admired qualities to its descendants. 

 It is a remarkable fact that the tastes of many birds, indirectly dis- 

 closed in such a manner, coincide very closely with the tastes of man- 

 kind at large. 



Not all birds, however, exhibit equally these aesthetic preferences. 

 Some large families, like those of the hawks, eagles, owls, and night- 

 jars, are noticeable neither for beauty of color nor for richness of song. 

 Other classes, again, like those of our own English hedge-birds, seem 

 rather musical than chromatically inclined in their tastes. As a rule, 

 we may say that birds of prey and nocturnal birds are very deficient in 

 aesthetic feeling, all their energies being apparently directed to swift- 

 ness of pursuit and skill in hunting; while, on the other hand, small 

 seed-eating birds, and those which live on little insects or other minute 

 animals, generally expend all their aesthetic sentiment on the faculty of 

 scng. But only those birds which live upon fruits, or the mixed nec- 

 tar and insects extracted from flowers, usually possess brilliant colors. 



I have already more than once pointed out to the readers of the 

 " Cornhill Magazine " the probable reason for this peculiar connection.* 

 The eyes of fruit-eating or flower-feeding animals become specially 

 adapted to the stimulation of colored light, and therefore the creatures 

 become capable of receiving special pleasure from such sources. Ac- 

 cordingly, those among their fellows which displayed brilliant colors 

 would prove most attractive, and would be chosen as mates for their 

 beauty. I have instanced before, among the flower-feeding species, 

 the numberless varieties of humming-birds, and the almost equal pro- 

 fusion of sun-birds, to which we may add a few other minor forms, such 

 as the brush-tongued lories; while among the fruit-eaters, the parrots, 

 macaws, cockatoos, toucans, barbets, nutmeg-pigeons, fruit-pigeons, 

 chatterers, and birds-of -paradise, may stand as cases in point. But it 

 will be more interesting here to glance briefly at the various modes 

 in which these colors are produced than to extend the list of species 

 which display them. 



* See a paper on " The Origin of Flowers," in " The Fopular Science Monthly Supple- 

 ment " for June, 1878 ; and another on " The Origin of Fruits," in "The Popular Science 

 Monthly" for September, 1878. 



