Colouration in Animals and Plants

by Alfred Tylor

That the nerves can affect the skin has already been pointed out in [Chapter VI.], in the case of herpes, and that it can affect colour is shown in the Hindoo described in the same place.

So marked, indeed, is this emphasis of sensitive parts that every hair of the movable feelers of a cat is shown by colour to be different in function from the hairs of the neck, or from the stationary mass of hair from which the single longer hair starts.

In the Badger, [Fig. 16], there is a bulge-shaped mass of coloured hair near the dorsal and lumbar regions, but it is axially placed. The shoulder and loins are well marked, although in a different manner from other species. In some species of deer, and other mammalia, there are white or coloured lines parallel to the spine, and also, as in birds, spots coalesce and form lines, and lines break up into spots.

The great anteater has what at first seems an exceptional marking on the shoulder, but a careful examination of the fine specimen which died at the Zoological Gardens in 1883, we were struck with the abnormal character of the scapula, and we must remember that, as Wallace and Darwin have pointed out, all abnormal changes of the teeth are correlated with changes in the hair. Moreover the muscles of the shoulder region are so enormously developed as to render this otherwise defenceless animal so formidable that even the jaguar avoids an embrace which tightens to a death-grip. This region is, therefore, precisely the one we should expect to be strongly emphasized. This being the case, we have really no exception in this creature.

Certain mammals are banded horizontally along their sides, thus losing most of their axial decoration, and this is well shown among the Viverridæ, and smaller rodents. Now, however conspicuous such animals may appear in collections, they are in their native haunts very difficult to detect. In all cases there is a marked dorsal line; and we suggest that the mature decoration is due to a suppression of the axial decoration for protective purposes, and a repetition of the dorsal decoration according to the law before enunciated. Indeed, in one case we were able to trace this pretty clearly, in the beautiful series of Sus vittatus in the museum at Leyden. This pig, an inhabitant of Java, when mature is a dark brown animal, but in the very young state it is clearly marked in yellow and brown, with a dark dorsal stripe, and spots, taking the line of the ribs, and over the shoulder and thigh. As the animal grows older, the spots run into stripes, and it becomes as clearly banded horizontally as the viverridæ. Finally the dark bands increase in width, until they unite, and the creature becomes almost uniformly brown.

We have not been able to see young specimens of the viverridæ, but a similar change may there occur, or it may have occurred in former times. We must also remember that these creatures are long-bodied, like the weasels, and hence they may have a tendency to produce long stripes.

In the case of our domestic animals, especially the oxen, the decoration seems often to have become irregular, but even here the emphasis of the extremities is generally clearly made out, and that of the limbs can often be traced. In horses this is better shown, and dappled varieties often well illustrate the points. Most horses at some time show traces of spots.

Sufficient has now been said to point out the laws we believe to have regulated the decoration of the animal kingdom. The full working out of the question must be left to the future, but it is hoped that a solid groundwork has been laid down.

Plate XI.