On riding across the monotonous grey Patagonian uplands, where often for hours one sees not the faintest tinge of bright colour, the intense glowing crimson of a cactus-fruit, or the broad shining white bosom of the Patagonian eagle-buzzard (Buteo erythronotus), perched on the summit of a distant bush, has had a strangely fascinating effect on me, so that I have been unable to take my eyes off it as long as it continued before me. Or in passing through extensive desolate marshes, the dazzling white plumage of a stationary egret has exercised the same attraction. At night we experience the sensation in a greater degree, when the silver sheen of the moon makes a broad path on the water; or when a meteor leaves a glowing track across the sky; while a still more familiar instance is seen in the powerful attraction on the sight of glowing embers in a darkened room. The mere brightness, or vividness of the contrast, fascinates the mind; but the effect on man is comparatively weak, owing to his fiery education and to his familiarity with brilliant dyes artificially obtained from nature. How strong this attraction of mere brightness, even where there is no mystery about it, is to wild animals is shown by birds of prey almost invariably singling out white or bright-plumaged birds for attack where bright and sober-coloured kinds are mingled together. By night the attraction is immeasurably greater than by day, and the light of a fire steadily gazed at quickly confuses the mind. The fires which, travellers make for their protection actually serve to attract the beasts of prey, but the confusion and fear caused by the bright glare makes it safe for the traveller to lie down and sleep in the light. Mammals do not lose their heads altogether, because they are walking on firm ground where muscular exertion and an exercise of judgment are necessary at every step; whereas birds floating buoyantly and with little effort through the air are quickly bewildered. Incredible numbers of migratory birds kill them-selves by dashing against the windows of lighthouses; on bright moonlight nights the voyagers are comparatively safe; but during dark cloudy weather the slaughter is very great; over six hundred birds were killed by striking a lighthouse in Central America in a single night. On insects the effect is the same as on the higher animals: on the ground they are attracted by the light, but keep, like wolves and tigers, at a safe distance from it; when rushing through the air and unable to keep their eyes from it they fly into it, or else revolve about it, until, coming too close, their wings are singed.