Page:The Zoologist, 4th series, vol 5 (1901).djvu/358

330 J. Storey, who describes the limits of insect vision, in the terms of a coarse mosaic or rough imperfect representation of the external world, the result of the perceptions acquired by their compound eyes; while he asserts that "the insect cannot see more details upon its own antennæ, close as they are to it, than we can with our own naked eye. We must therefore dismiss from our thoughts the mistaken impression that insects see very minute objects far beyond human vision." Nor can we, as remarked before, conclude that they appreciate colours similarly to ourselves. The question was well put by Lord Rayleigh some years ago, who added the remark:—"Surely this is a good deal to take for granted when it is known that even among ourselves colour-vision varies greatly, and that no inconsiderable number of persons exist to whom, for example, the red of the scarlet geranium is no bright colour at all, but almost a match with the leaves." The only rejoinder to this proposition at the time was the suggested argument based on the spectrum of the light of the Firefly, which had been found to be perfectly continuous, without traces of lines either bright or dark, and to extend from about the line C in the scarlet to F in the blue. It is composed of rays which act powerfully on the eye, but produce little thermal or actinic effect. In other words, the fly, in producing its light, wastes but little of its power. The writer, however, was careful to add:—"This, it is true, tells us nothing as to the colour sensations of the insect, but it appears to show that the same rays are luminous to its eyes which are luminous to ours." This is precisely the view here again suggested—the same ray or object is seen as by ourselves; but the colour, size, or structure of both respectively may be altogether different, or at least considerably diverse from those apprehended by our own cognitions. This does not, however, necessarily invalidate the conclusions we have formed as to the actual existence of some forms of protection by what we understand as mimicry or protective resemblance. It may be taken to prove that both the object resembled