THE COLORS OF ANIMALS AXD PLANTS. 



43 



One word more. If my language has given any 

 believer pain, I regret it sincerely. It may have 

 been somewhat obscure, since it has been so 

 widely arraigned, and I think misconceived. My 

 position is this : The idea of a glorified energy 

 iu an ampler life is an idea utterly incompati- 

 ble with exact thought, one which evaporates in 

 contradictions, in phrases which when pressed 

 have no meaning. The idea of beatific ecstasy is 

 the old and orthodox idea ; it does not involve so 

 many contradictions as the former idea, but then 

 it does not satisfy our moral judgment. I say 

 plainly that the hope of such an infinite ecstasy 

 is an inane and unworthv crown of a human life. 



And when Dr. Ward assures me that it is merely 

 the prolongation of the saintly life, then I say the 

 saintly life is an inane and unworthy life. The 

 words I used about the " selfish " view of futurity, 

 I applied only to those who say they cure for 

 nothing but personal enjoyment, and to those 

 whose only aim is "to save their own souls." 

 Mr. Baldwin Brown has nobly condemned this 

 creed in words far stronger than mine. And 

 here let us close with the reflection that the lan- 

 guage of controversy must always be held to apply 

 not to the character of our opponents, but to the 

 logical consequences of their doctrines, if uncor- 

 rected and if forced to their extreme. 



THE COLOES OF AXIMALS AXD PLAXTS. 1 



By ALFRED EUSSEL WALLACE. 



II.— THE COLORS OF PLANTS. 



THE coloring of plants is neither so varied 

 nor so complex as that of animals, and its 

 explanation, accordingly, offers fewer difficulties. 

 The colors of foliage are, comparatively, little 

 varied, and can be traced in almost all cases to a 

 special pigment termed chlorophyl, to which is 

 due the general green color of leaves ; but the 

 recent investigations of Mr. Sorby and others 

 have shown that chlorophyl is not a simple green 

 pigment, but that it really consists of at least 

 seven distinct substances, varying in color from 

 blue to yellow and orange. These differ in their 

 proportions in the chlorophyl of different plants ; 

 they have different chemical reactions ; they are 

 differently affected by light ; and they give dis- 

 tinct spectra. Mr. Sorby further states that 

 scores of different coloring-matters are found in 

 the leaves and flowers of plants, to some of which 

 appropriate names have been given, as erythro- 

 phyl, which is red, and phaiophyl, which is 



1 In the first part of this paper I used the term " vol- 

 untary sexual selection " to indicate the theory that many 

 of the ornaments of male animals have been produced by 

 the choice of the females, and to distinguish it from that 

 form of sexual selection which explains the acquisition of 

 weapons peculiar to male animals as due to the selective 

 influence of their combats and struggles for the possession 

 of the females. I find that Mr. Darwin thinks the term 

 "voluntary" not strictly applicable, and I therefore pro- 

 pose to alter it to li conscious" or '-perceptive," which 

 seem free from any ambiguity, and make not the least 

 difference to my argument. 



brown ; and many of these differ greatly from 

 each other in their chemical composition. These 

 inquiries are at present in their infancy, but, as 

 the original term chlorophyl seems scarcelv ap- 

 plicable under the present aspect of the subject, 

 it would perhaps be better to introduce the anal- 

 ogous word chromophyl as a general term for the 

 coloring-matters of the vegetable kingdom. 



Light has a much more decided action on 

 plants than on animals. The green color of leaves 

 is almost wholly dependent on it ; and although 

 some flowers will become fully colored in the 

 dark, others are decidedly affected by the absence 

 of light, even when the foliage is fully exposed to 

 it. Looking, therefore, at the numerous colored 

 substances which are developed in the tissues of 

 plants — the sensitiveness of these pigments to 

 light, the changes they undergo during growth 

 and development, and the facility with which new 

 chemical combinations are effected by the physio- 

 logical processes of plants, as shown by the end- 

 less variety in the chemical constitution of vege- 

 table products — we have no difficulty in compre- 

 hending the general causes which aid in produc- 

 ing the colors of the vegetable world, or the 

 extreme variability of those colors. We may, 

 therefore, here confine ourselves to an inquiry 

 into the various uses of color in the economy of 

 plants ; and this will generally enable us to un- 

 derstand how it has become fixed and specialized 



