The large majority of monkeys are protectively coloured with some shade of brown or grey, with specially marked faces. Entire packs of Ceylonese species will, at the slightest alarm, become invisible by crouching on a palm-tree. One of the most strikingly coloured African monkeys is jet black with a white bushy tail, and a face surrounded by a white ring, or mantle of long silky hair. He thus simulates so strikingly the hanging white lichens upon the trees that he is rarely seen by his enemies.
A book might be written upon the various ways that animals, when closely associated with other animals or human beings, imitate them. Darwin says that "two species of wolves, which had been reared by dogs, learned to bark, as does sometimes the jackall," and it is well known that certain dogs, when reared by cats, imitate their habits, even to the licking of their feet and the washing of their faces. If a mongrel dog associates with a trained dog for any period of time it is remarkable the progress he will make. For this same reason young dogs are carried on hunting trips with trained dogs that they may learn by imitation the art of hunting.
In the whole realm of Nature there is nothing more wonderful than this matter of protective colouration. Animals do not monopolise the art. It extends through the whole world of living creatures. The fact that individual animals have no voluntary control over their own colour is eloquent testimony as to the existence of mysterious life forces and racial evolutions which are still far beyond the grasp of man's understanding. To see a tiny chameleon adapt his colouring to his environment, be it red, green, or yellow, in the twinkling of an eye, is to have seen an argument for God Himself.
_"Nay, what is Nature's self, But an endless strife towards Music, euphony, rhyme?"_
The great thinkers of the age believe that the world is one marvellous blending of innumerable and varied voices. This unison of sound forms the great music of the spheres, which the poets and philosophers have written so much about. Even from a purely scientific point of view, there is no denying that this music exists. Aviators tell us that when they listen from a distance to the myriads of noises and sounds that arise over a great city, these are all apparently lost in a modulated hum precisely like the vibrations of an immense tuning-fork, and appearing as but a single tone. Thus the immense noise going from our world is musically digested into one tone, and the aviator soaring above the earth hears only the one sound--the music of the spheres.