Page:Popular Science Monthly Volume 75.djvu/559

Rh over the premises of American country folk, it is very rare to see one of them, except by encountering him in the hen-house. This is the more significant in view of their well-known temerity and disinclination to get out of one's way. Their white pattern, if seen at all, and even when observed to move, is easily mistaken for some inanimate detail of the scene, some shifting shine on a wet leaf, or other of the above-mentioned light-colored details of the place. There seldom pass many minutes without some breeze to set in motion the many more or less white details of the shrubbery, so that the disembodied light patch of this little hunter's coat may move, even within the short visibility-range that we have discovered it to possess, yet by no means commonly attract our attention. It is certainly the universal experience of American country dwellers that although in their domestic duties they must frequently pass within a few feet of skunks, yet the whole family together scarcely see one a year. Under shrubbery, moonlight, which might be expected to reveal these animals, adds, on the contrary, to the scene hundreds of white patterns, and these often all in motion, so that what was before a comparatively negative form of concealment becomes a most brilliant and positive illusion. The skunk's pattern so absolutely reproduces the hundred surrounding ones, often all shifting in a thousand directions, that even when the animal is near enough to be seen, he is almost sure to escape detection. Dr. Merriam first called my attention to this, and also to a very clear statement of it by Verrill. Merriam says that spilogales amidst cactus shadows in moonlight are practically impossible to follow with the eye. It is easy to see that this must apply to the appearance of all the other top-patterned species under similar circumstances. This is one more instance of increased illumination producing increased procryptic effect, such as we also see in the operation of counter-shading.

These simple diagrams, then, prove that it is not the diversification into brilliantly contrasted pattern that makes its wearer conspicuous, or that is the most efficacious way to make him recognizable. It is the very juxtaposition of the skunk's black that makes his white fade out of sight at a short distance, and in a nearer view, amidst the many light spots likely to be in sight, one more has often no significance to a spectator; but if this light color took the full shape of a skunk, then, of course, it would make him recognizable. In the next plates we shall see what is the main cause of the frequent conspicuousness, during motion, of all aerial species, or of any that by virtue of being taller than others, are, to these lower-level observers, practically the same as aerial, because of looming against their sky.

But let us turn aside to notice the circumstances of the species already recognized by naturalists as procryptically colored. These are merely such species as live, or rest by day, in actual contact with their