Is it not a curious, yet a comprehensible circumstance, that the tastes which thus show themselves in the development, by natural selection, of lovely flowers, should also show themselves in the marked preference for beautiful mates? Poised on yonder sprig of harebell stands a little purple-winged butterfly, one of the most exquisite among our British kinds. That little butterfly owes its own rich and delicately shaded tints to the long selective action of a million generations among its ancestors. So we find throughout that the most beautifully coloured birds and insects are always those which have had most to do with the production of bright-coloured fruits and flowers. The butterflies and rose-beetles are the most gorgeous among insects: the humming-birds and parrots are the most gorgeous among birds. Nay more, exactly like effects have been produced in two hemispheres on different tribes by the same causes. The plain brown swifts of the North have developed among tropical West Indian and South American orchids the metallic gorgets and crimson crests of the humming-bird: while a totally unlike group of Asiatic birds have developed among the rich flora of India and the Malay Archipelago the exactly similar plumage of the exquisite sun-birds. Just as bees depend upon flowers, and flowers upon bees, so the colour-sense of animals has created the bright petals of blossoms; and the bright petals have reacted upon the tastes of the animals themselves, and through their tastes upon their own appearance. XII. _SPECKLED TROUT._