THEORIES OF MIMICRY 553 



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 fre- 

 quently 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 thou- 

 sand 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 spec- 

 tator; 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 daij, in actual contact with their 



. VOT.. LXXV. 37. 



