524 



NATURE 



{Sept. 12, 1878 



time altogether conforms to that law of polarity here 

 brought forward. Thus while the feathers on the head 

 and back of this familiar species are of a bright cerulean 

 blue, those of the breast and under-surface are mostly 

 yellow. Higher than the birds it seems useless to seek 

 for the association of the two complementary tints under 

 notice, though singularly enough one of these, the blue, turns 

 up where it might be least anticipated, namely, amongst 

 certain of the baboons, or Simiadae, whose cheeks and re- 

 markable posterior callosities are not unfrequently coloured 

 bright cobalt. So late as the commencement of historic 

 times our noble ancestors are reported to have supplied 

 what nature had denied them in this department by the 

 adorning of their persons with the juice of woad. 



Turning now to the second complementary combination, 

 that of red and green, it will be found to be far more 

 extensively distributed even than that just discussed, 

 birds, reptiles, fishes, and almost every class of the inver- 

 tebrate kingdom supplying an important quota in which 

 these colours are placed in juxtaposition. From among 

 the first-named, the parrot tribe, woodpeckers, certain 

 pigeons {Ptilonoptis), trogans, and humming-birds, fur- 

 nish abundant examples. Among lizards may be men- 

 tioned the Indian genus Calotesj while the ballan and 

 corkwing wrasses, the Connemara sucker, and even the 

 common stickleback in its breeding-dress, illustrate 

 i ^miliar examples of our indigenous species of fish in 

 which green and red constitute the two dominant hues. 

 To this last-named list of fishes might be added innu- 

 merable exotic types. With the crustacean class green 

 and red appears to be a scarce combination, but 

 one marine Isopod {Spheroma), remarkable for the varia- 

 tion in colour of different individuals, supply an excep- 

 tional illustration, I having by me alive at the present 

 moment two examples, one of which is pale green, and 

 the other scarlet. A spider, with whose technical name I 

 am not familiar, but which often occurs on laurel bushes, 

 has its body apple-green, supplemented with a bright 

 red spot in the posterior region. Aphides, whose bodies 

 are usually green, have frequently associated with the 

 same scarlet or crimson eyes, and the same two colours 

 will be found to be the prevalent tints of the larvae of 

 many lepidopterous insects. Green and red ascidians, 

 worms, and zoophytes might likewise be enumerated, and 

 the same combination is further traceable down to the 

 Protozoa, and within the precincts of that debatable 

 ground from whence both plants and animals take com- 

 mon origin. 



Here, indeed, the subject assumes its most interesting 

 and important phase, it being evidently at this initial 

 point that the key and origin of the whole attendant phe- 

 nomena are to be sought. Among a number of these 

 humble unicelhilar organisms, including apparently as 

 undoubted animals the Euglenae or Astasias, and as true 

 plants the Thecomonads and Volvocinae, it will be found 

 that the brilliant green hue of the general cell-substance 

 is supplemented at one point by a brilliant scarlet speck, 

 with which, in the case of animal organisms, the proper- 

 ties of a visual organ have been frequently associated. 

 Though this interpretation does not meet with general 

 support, it is remarkable how persistent is the presence 

 of scarlet eyes among the more minute representatives 

 of several invertebrate classes, including Insecta, Crus- 

 tacea (some of these monocular), Annelids, and even 

 Echinoderms, as typified by the starfish tribe. Advancing 

 further on the vegetable side, the complementary colours of 

 red and green, as first foreshadowed in unicellular Phytozoa, 

 become still more conspicuously associated. Altogether 

 apart from the floral elements the colour red constantly 

 accompanies the more general green cellular structure of 

 the stems, petioles, and leaf venation of ordinary plants. 

 One remarkable Mexican species, indeed, Pointsetlia pul- 

 cherrima, affords an instance in which the whole foliage 

 forming a rosette at the terminal portion of the plant is 



the most brilliant scarlet, while that of the lower part is 

 simply green. Calladiufns, Begonias, and many other 

 types might be quoted, in which the same two colours are 

 equally blended in the leaves. Among the flowerless 

 cryptogams, again, the group of the Bryaceae, or moss 

 tribe, yields further analogous and corroborative data. 

 The peculiar fimbriated structure or peristome, which 

 upon the dehiscence of the operculum guards the aperture 

 of the spore capsules in this group, being in the majority 

 of instances bright scarlet or crimson. The brilliant 

 floral elements of the phanerogamic class are not so easily 

 subordinated to that law of polarity, which appears to 

 have left its impress on the simpler vegetative parts. 

 Cross-fertilisation and numerous other external conditions 

 and surroundings have no doubt exercised their influence 

 in this case to an extent parallel to, though not identical 

 with, what obtains among the Lepidopterous group of the 

 animal series. Even here, however, it is a matter of 

 question whether red is not the colour most extensively 

 distributed. Certain forest trees, for example, such as the 

 larch, poplar, and hazel (female flower), form interesting 

 exceptions among a group more usually altogether want- 

 ing in brilliant floral decoration, and in all of which 

 instances red is the characteristic hue of the flowers they • 

 bear. 



How, or in what manner, the varied colours of nature' 

 were first called into existence is a problem that yet 

 remains to be solved. Without presuming to put forward 

 or propose any arbitrary interpretation of this primeval 

 derivation, the following data may be tentatively sub- 

 mitted. The initial term of the series, as represented 

 amongst the lowest animals and lowest plants, and in the 

 latter instance continued throughout the higher forms, is 

 evidently the colour green. Associated with vegetable 

 life it takes the form of chlorophyll, and as such is alto- 

 gether dependent for its origin and existence upon the 

 influence of solar light. Shut off from such influence, this 

 element fails to produce itself, and vegetable tissues 

 remain white, as instanced in the artificial cultivation of 

 seakale and other culinary herbs. Prolonged isolation 

 from such light, however, results in the arrest of the vital 

 functions, and this circumstance fully explains the absence 

 of chlorophyll producing vegetation below that depth in 

 the ocean to which solar rays have access.^ Green again, 

 is not a simple colour, but a combination of two others — 

 blue and yellow. May not therefore its origin be remotely 

 related to the effect of the solar rays, technically white 

 and colourless, but yellow to the external senses as repre- 

 sented by ordinary sunshine and upon the artist's canvas, 

 acting in concert with the blue ether of which our outer 

 atmosphere is composed ? 



Given this initial colour green, the three primary hues- 

 of nature follow as a necessary consequence : — Blue and^ 

 yellow by the resolution of the initial factor into its con- 

 stituent parts, and red as its direct or reflex product in 

 abeyance to the law of polarity. That this latter law 

 exerts a considerable influence in the origin and distribu- 

 tion of those glorious tints of nature which may be said to 

 constitute its most potent charm, will scarcely fail to- 

 recommend itself to the attention of those specially con- 

 versant with the physics of colour, and in whose hands 

 this subject may prove susceptible of important develop- 

 ment. 



W. Saville Kent 



I Reference may be appropriately made here to the predominant coIourjM 

 fixed deep-sea organisms, such as sponges and corals. In the hexactinellid 

 sponge-form Phceroiuwa {Holtenia) characteristic of abyssal depths, the 

 colour, as observed by the writer In association with examples procured from 

 a depth of from five to six hundred fathoms off the coast of Portugal, and la 

 connection with the dredging expedition of Mr. Marshall Hall's yacht the 

 Nortta recently referred to, was the most brilliant orange. This hue was 

 likewise observed to be characteristic of the soft parts of the large deep- 

 water branching coral Dendrophyllia ramea obtained in the same expedition. 

 It will at once occur that this colour, orange, is directly complementary or 

 polar to that of the superincumbent mass of water, always distinguished when 

 overlying such profundities by its deep cerulean hue. 



