TEE COLORS OF ANIMALS AND PLANTS. 



523 



universal admiration. The relation of this wealth 

 of color to our mental and moral nature is indis- 

 putable. The child and the savage alike admire 

 the gay tints of flower, bird, and insect ; while to 

 many of us their contemplation brings a solace 

 and enjoyment which is both intellectually and 

 morally beneficial. It can then hardly excite sur- 

 prise that this relation was long thought to afford 

 a sufficient explanation of the phenomena of color 

 in Nature ; and although the fact that — 



" Full many a flower is born to blush unseen, 

 And waste its sweetness on the desert air"— 



misrht seem to throw some doubt on the sufficien- 



O 



cy of the explanation, the answer was easy — that, 

 in the progress of discovery, man would, sooner 

 or later, find out and enjoy every beauty that the 

 hidden recesses of the earth have in store for him. 

 This theory received great support from the diffi- 

 culty of conceiving any other use or meaning in 

 the colors with which so many natural .objects 

 are adorned. Why should the homely gorse be 

 clothed in golden raiment, and the prickly cac- 

 tus be adorned with crimson bells ? Why should 

 our fields be gay with buttercups, and the heath- 

 er-clad mountains be clad in purple robes ? Why 

 should every land produce its own peculiar floral 

 gems, and the Alpine rocks glow with beauty, if 

 not for the contemplation and enjoyment of man ? 

 What could be the use to the butterfly of its gayly- 

 painted wings, or to the humming-bird of its jew- 

 eled breast, except to add the final touches to a 

 world-picture, calculated at once to please and to 

 refine mankind ? And even now, with all our re- 

 cently-acquired knowledge of this subject, who 

 shall say that these old-world views were not in- 

 trinsically and fundamentally sound ; and that, al- 

 though we now know that color has " uses " in 

 Nature that we little dreamed of, yet the relation of 

 those colors to our senses and emotions may be 

 another and perhaps more important use which 

 they subserve in the great system of the universe? 



We now propose to lay before our readers a 

 general account of the more recent discoveries on 

 this interesting subject ; and, in doing so, it will 

 be necessary first to give an outline of the more 

 important facts as to the colors of organized be- 

 ings ; then to point out the cases in which it has 

 been shown that color is of use ; and, lastly, to 

 endeavor to throw some light on its nature, and 

 the general laws of its development. 



Among naturalists, color was long thought to 

 be of little import, and to be quite untrustworthy 

 as a specific character. The numerous cases of 

 variability of color led to this view. The occur- 

 rence of white blackbirds, white peacocks, and 



black leopards; of white bluebells, and of white, 

 blue, or pink milkworts, led to the belief that col- 

 or was essentially unstable, that it could therefore 

 be of little or no importance, and belonged to 

 quite a different class of characters from form or 

 structure. But it now begins to be perceived 

 that these cases, though tolerably numerous, are, 

 after all, exceptional ; and that color, as a rule, is 

 a constant character. The great majority of spe- 

 cies, both of animals and plants, are each distin- 

 guished by peculiar tints which vary very little, 

 while the minutest markings are often constant in 

 thousands or millions of individuals. All our field 

 buttercups are invariably yellow, and our poppies 

 red, while many of our butterflies and birds re- 

 semble each other in every spot and streak of col- 

 or through thousands of individuals. We also 

 find that color is constant in whole genera and 

 other groups of species. The Genistas are all 

 yellow, the Erythrinas all red, many genera of 

 Carabidse are entirely black, whole families of 

 birds — as the Dendrocolaptidae — are brown, while 

 among butterflies the numerous species of Lyca?na 

 are all more or less blue, those of Pontia white, 

 and those of Callidryas yellow. An extensive 

 survey of the organic world thus leads us to the 

 conclusion that color is by no means so unim- 

 portant or inconstant a character as at first sight 

 it appears to be ; and the more we examine it the 

 more convinced we shall become that it must 

 serve some purpose in Nature, and that besides 

 charming us by its diversity and beauty it must 

 be well worthy of our attentive study, and have 

 many secrets to unfold to us. 



In order to group the great variety of facts 

 relating to the colors of the organic world in 

 some intelligible way, it will be best to consider 

 how far the chief theories already proposed will 

 account for them. One of the most obvious and 

 most popular of these theories, and one which is 

 still held, in part at least, by many eminent natu- 

 ralists, is, that color is due to some direct action 

 of the heat and light of the sun, thus at once 

 accounting for the great number of brilliant birds, 

 insects, and flowers, which are found between the 

 tropics. But here we must ask whether it is 

 really the fact that color is more developed in 

 tropical than in temperate climates, in proportion 

 to the whole number of species ; and, even if we 

 find this to be so, we have to inquire whether 

 there are not so many and such striking excep- 

 tions to the rule as to indicate some other causes 

 at work than the direct influence of solar light 

 and heat. As this is a most important question, 

 we must go into it somewhat fully. 



