Page:Popular Science Monthly Volume 75.djvu/556

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tance.[1] The same thing is true of the letters, the unmarked ones being legible much farther than the others. Fig. 2 shows exactly the same effect with reversed colors. That part of the gray butterfly next the black ocellus fades, as one recedes, until it becomes pure white like the background, leaving the rest of the butterfly to continue visible at a much greater distance. In both these cases the effect of conspicuous pattern proves to be the exact reverse of the old hypothesis on which the Bates and Wallace theories so largely rest. Figs. 3 and 4 will, I think, still more surprise the many writers who, from Darwin and Wallace down to the present time, are accustomed to say of one or another brilliantly pied species, that its patterns are so conspicuous that one can see it a hundred yards off. It is here shown that it can not be the brilliancy or conspicuousness of the animal's patterns that enables them thus to see him from afar, since these very characters here produce the opposite effect. The reader will discover, in looking from a greater and greater distance, that it is the normally colored, strongly pied butterfly and skunk, respectively, that fade first, and that all of the remaining six figures can be seen further. (These can be tested not only by distance, but by decreased illumination, and, especially for the latter means, a still more satisfactory test of the skunk can be made by using life-size figures and turning down the lights in a hall, or studying them out of doors as night comes on.) He will discover that the supposed white blazon actually serves to efface the black animal on a nearer view (especially if seen through the leaves). He can not fail, either, to perceive that an all-white skunk, being exempt from the risk of giving an impression of two different things, a black one, and a white one, would in the long run, be, also, the more recognizable when seen against any ground, except snow.[2] It is not yet generally perceived that in the scenery about us every spot means to a casual observer one thing, and it follows that two different color-patches, as of the skunk, amidst the million color-patches in sight, tend, especially when more or less eclipsed by vegetation, to mean, not one pied animal, but two different elements of the scene. It must be remembered that the skunk's scene is a night scene, commonly abounding, in wild places, in black shadow masses relieved here and there by light spots made by bleached twigs, fragments of fallen birches, shining wet spots, etc., and, what is by far the most essential fact, with all visibility whatsoever at the minimum. In fact the whole "warning-color" theory in the case of these nocturnal species smacks of the laboratory. For instance, although skunks abound all

  1. In most butterflies, the body itself is wonderfully effaced by having its color blent off into the wing; yet it profits greatly by the effacing-power of the strong pattern to right and left.
  2. To learn the superiority of monochrome for identification, paint a uniform tone over a chiselled inscription that has become hard to read because of weather-stains, and instantly it is as legible as when it was first cut.