It was known, of course, that Arctic foxes and hares became white in winter, and that each benefited by its change, and suffered from the change of the other; the snow tint which enabled the hare to escape also facilitating the unobserved approach of the fox. It was also known that many desert animals were of the colour of the sandy plain they wandered over, and that tree-snakes and tree-frogs were often green. But it seemed incredible that the varied shades or bright adornments of the living world should each and all be governed by rigid laws, generally connected with the welfare of the organisms so furnished. Here, if anywhere, the reign of utilitarianism in Nature appeared to be at an end, and creative fancy to have full play, regardless but of the harmony and beauty thus revealed to appreciating eyes. The labours and fruitful thoughts of Bates and Wallace have, however, opened up a wide field for most interesting inquiry. They have made it evident that in many instances the most direct utility accompanies colour both in animals and plants. The colours of flowers serve to attract insects and birds, by the visits of which they are fertilized or their fertility is greatly augmented. It is this relation between attractiveness and insect fertilization which explains the absence of colour from the flowers of plants which are fertilized only by the wind, such as the fir trees before-mentioned, oaks, beeches, nettles, sedges, and many others. It also explains the conspicuousness of the flowers of many oceanic islands, such as those of the Galapagos archipelago. But it also explains, as Mr. Wallace has pointed out, the remarkable beauty of Alpine flowers, by their need of attracting insects from a distance, the conspicuous patches of bright colour serving thus to attract wandering butterflies upwards from the valleys.