Page:Popular Science Monthly Volume 79.djvu/25

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CONCEALING COLORATION

could now see the deer, and all agreed that it was these white stripes that had fooled them. Dr. C. Hart Merriam said it was a most conclusive demonstration (though he still believed that such marks exist also for purposes of display, under other conditions).

The way this deer demonstration brings to instant ridicule the extraordinarily positive statements of Theodore Roosevelt must set the reader wondering about the value of the remainder of his attack. The simple fact is that Roosevelt, like most of the rest of the world, is totally ignorant of a great optical principle which has lain right under people's noses, and to which I have at last called attention, and which can not possibly remain ignored. All the various objections and doubts about our book, including this extraordinary tirade of Roosevelt's, have been possible only because of people's not seeing this principle.

The principle[1] is, basally, merely this: that if you lie on the floor you will have not the floor but the ceiling to look at, while if you were fastened to the ceiling you would see not the ceiling but the floor. All over this planet, and all over every other planet that receives light-vibrations and possesses detached objects of any sort, either on or above its surface, this law rules the aspect of every object in its appearance from the view-point of each other object. All such detached objects are forever

PSM V79 D025 Colour camouflage in nature.png
This diagram shows that Roosevelt is again exactly wrong when he says that to the lower-leveled eye of a wolf or cougar, a prongbuck's white rump shows now against the sky and now below it, according to this enemy's distance. If the antelope's rump is above the cougar's eye the same proportion of it will show against the cougar's sky at one distance as at another.
  1. Erasmus Darwin perceived this principle, but got confused in carrying it out—trying to make it explain the juxtaposition of brown backs and white bellies; the white of the bellies being, he thought, nature's attempt to match the white of the sky, for eyes beneath. Of course this under white can not do that, being always in shadow, and therefore practically dark brown—utterly too dark to match the over-head sky. On the other hand, white patterns on animals' upper slopes obey in every respect the law he foresaw, and operate upon the sight of such beholders as look from a lower level, except, of course, when the wearer is directly over them.