TEE COLORS OF ANIMALS AND PLANTS. 



47 



west coast of South America, and with a tolera- 

 bly luxuriant vegetation in the damp mountain- 

 zone, yet produce hardly a single conspicuously- 

 colored flower ; and this is correlated with, and 

 no doubt dependent on, an extreme poverty of 

 insect-life, not one bee and only a single butter- 

 fly having been found there. 



Again, there is reason to believe that some 

 portion of the large size and corresponding show- 

 iness of tropical flowers is due to their being fer- 

 tilized by very large insects and even by birds. 

 Tropical sphinx-moths often have their probosces 

 nine or ten inches long, and we find flowers whose 

 tubes or spurs reach about the same length ; while 

 the giant bees, and the numerous flower-sucking 

 birds, aid in the fertilization of flowers whose 

 corollas or stamens are proportionately large. 



I have now concluded this sketch of the gen- 

 eral phenomena of color in the organic world. I 

 have shown reasons for believing that its pres- 

 ence, in some of its infinitely-varied hues, is more 

 probable than its absence, and that variation of 

 color is an almost necessary concomitant of vari- 

 ation of structure, of development, and of growth. 

 It has also been shown how color has been ap- 

 propriated and modified both in the animal and 

 vegetable world, for the advantage of the species 

 in a great variety of ways, and that there is no 

 need to call in the aid of any other laws than 

 those of organic development and " natural selec- 

 tion " to explain its countless modifications. From 

 the point of view here taken, it seems at once 

 improbable and unnecessary that the lower ani- 

 mals should have the same delicate appreciation 

 of the infinite variety and beauty — of the deli- 

 cate contrasts and subtile harmonies of color — 

 which are possessed by the more intellectual 

 races of mankind, since even the lower human 

 races do not possess it. All that seems required 

 in the case of animals is a perception of distinct- 

 ness or contrast of colors ; and the dislike of so 

 many creatures to scarlet may, perhaps, be due 

 to the rarity of that color in Nature, and to the 

 glaring contrast it offers to the sober greens and 

 browns which form the general clothing of the 

 earth's surface. 



The general view of the subject now given 

 must convince us that, so far from color being — 

 as it has sometimes been thought to be — unim- 

 portant, it is intimately connected with the very 

 existence of a large proportion of the species of 

 the animal and vegetable worlds. The gay col- 

 ors of the butterfly and of the Alpine flower 

 which it unconsciously fertilizes while seeking 



for its secreted honey, are each beneficial to its 

 possessor, and have been shown to be dependent 

 on the same class of general laws as those which 

 have determined the form, the structure, and the 

 habits of every living thing. The complex laws 

 and unexpected relations which we have seen to 

 be involved in the production of the special col- 

 ors of flower, bird, and insect, must give them 

 an additional interest for every thoughtful mind ; 

 while the knowledge that, in all probability, each 

 style of coloration, and sometimes the smallest 

 details have a meaning and a use, must add a 

 new charm to the study of Nature. 



Throughout the preceding discussion we have 

 accepted the subjective phenomena of color — 

 that is, our perception of varied hues, and the 

 mental emotions excited by them — as ultimate 

 facts needing no explanation. Yet they present 

 certain features well worthy of attention, a brief 

 consideration of which will form a fitting sequel 

 to the present essay. 



The perception of color seems, to the present 

 writer, the most wonderful and the most myste- 

 rious of our sensations. Its extreme diversities 

 and exquisite beauties seem out of proportion to 

 the causes that are supposed to have produced 

 them, or the physical needs to which they minis- 

 ter. If we look at pure tints of red, green, blue, 

 and yellow, they appear so absolutely contrasted 

 and unlike each other that it is almost impossible 

 to believe (what we nevertheless know to be the 

 fact) that the rays of light producing these very 

 distinct sensations differ only in wave-length and 

 rate of vibration ; and that there are from one to 

 the other a continuous series and gradation of 

 such vibrating waves. The positive diversity we 

 see in them must, then, depend upon special 

 adaptations in ourselves ; and the question arises, 

 For what purpose have our visual organs and 

 mental perceptions become so highly specialized 

 in this respect ? When the sense of sight was 

 first developed in the animal kingdom we can 

 hardly doubt that what was perceived was light 

 only, and its more or less complete withdrawal. 

 As the sense became perfected, more delicate 

 gradations of light and shade would be perceived ; 

 and there seems no reason why a visual capacity 

 might not have been developed as perfect as our 

 own, or even more so, in respect of light and 

 shade, but entirely insensible to differences of 

 color, except in so far as these implied a differ- 

 ence in the quantity of light. The world would 

 in that case appear somewhat as we see it in good 

 stereoscopic photographs ; and we all know how 



