Russel Wallace : Alfred Russell Wallace (sic)
Mr. Alfred Russel Wallace, in commenting upon the views expressed by Mr. Tylor, said the subject which he had introduced was so vast that it would require an entire evening to go into it fully. It happened that he had a theory of his own, which did not agree with Mr. Tylor's, and he could not very well express his views without referring to this theory. In order to explain the great varieties of colour which are to be seen in nature, it is necessary, in the first place, to consider the physical nature and origin of colour, for that is the foundation of the whole matter. It is now generally held that the colour of natural objects is a subjective phenomenon. The objects themselves are devoid of colour, but they each absorb some of the different coloured rays of which white light is composed, and reflect the other rays, and the object appears to be of the colour of the rays or mixture of rays which it reflects. Thus green objects absorb the red rays and reflect the yellow and the blue, whilst purple objects absorb the yellow and reflect the red and the blue. The rays which each particular object will absorb and reflect will depend upon the nature and constitution and size of the molecules of which it is made up; and any alteration in these, from any cause, will probably produce a corresponding alteration in the colour.
As there is every conceivable variety in the molecular structure of different bodies in nature, there is, necessarily, every variety of colour. Some colours, or groups of colours, are much more abundant than others, but, as a rule, in the animal world, obscure colours predominate.
Mr. Wallace stated that the conclusion at which he had arrived was, that, primarily, there is no reason why any animal should be of any particular colour. It may be of any colour, and as a matter of fact, every possible variety of colour does exist in [[p. lvi]] nature. But the particular colour which any particular animal possesses, is the result of an infinite variety of secondary causes which render certain colours useful and other colours hurtful to the animal. In birds, and in some other animals, the brilliant colouring of the males is usually most intense in the breeding season, when the animal is in the fullest vigour. But the one thing of all others which most affects the development of colour is the need of protection or concealment. Almost all animals need concealment because they have enemies, and those which are too powerful to fear any enemies still need concealment to enable them to catch their prey. If there were no need for protection and concealment, the beautiful colours of tropical birds, instead of being exceptional, would probably be the rule, and there would be brilliant colours throughout nature. The large Felidæ afford good instances of the advantages to animals of particular colouring. The Ounce for instance, which passes much of its time in trees, is spotted, and for this reason cannot be easily seen amongst the foliage of trees. The Tiger, on the other hand, which lives mostly in jungle and tall grass, and is never seen in trees, is striped, and so nearly resembles the grass and jungle in colour, that in it it is quite invisible at a short distance. In a similar way animals that frequent trees of different kinds do not acquire the colour of any tree in particular, whilst animals that frequent only one kind of tree, as a rule, acquire the colour of the tree which they frequent. The same law of concealment applies to birds. The bright colours of birds are principally on the breast, where they would not be seen when the birds are sitting on their nests or perched on trees, except from underneath. The reason why tropical birds have so much colour is that the vegetation is abundant and the forests dense, and hence there is less need for concealment. It is supposed by a good many people that brilliancy of colour is due to the intensity of the sun, but that is a mistake, because in the desert, where the sun is strongest, animals, as a rule, are of the colour of the sand. Mr. Wallace further disputed the theory that brilliancy of colour depends on rapidity of motion, remarking that wings of birds have generally little brilliancy of colour in them.
Dr. Henry Woodward, F.R.S., supported the views expressed by Mr. Wallace, and fully concurred in his opinion that the colour of animals was mainly determined by the necessity for concealment. In connection with this subject he mentioned that in Sir Thomas Fowell Buxton's coverts in Norfolk, white varieties of the common Pheasant were encouraged, and were, in consequence, rather numerous. The gamekeepers, however, did not like them, because, from their [[p. lvii]] conspicuous colouring, they attracted all the "vermin" in the neighbourhood, and the gamekeepers had great difficulty in preserving them from the attacks of Weasels and Stoats, and Birds of Prey.
Referring to what Mr. Wallace had said as to the colours of male animals being often brightest when they were most vigorous, he mentioned that at his own house he had an aquarium which contained a number of Sticklebacks which were preparing for spawning. The males were brilliantly coloured, but, being very pugnacious, were constantly fighting, and, as each of these was beaten his bright colours faded or disappeared. One of the larger males for a long time held his own against the others, but at last he was beaten, and then his colours also faded. . . .