CONCEALING COLORATION 33 



Our book 6 was written only after all its facts were verified. It con- 

 tains essentially nothing hut facts, and might have been called an 

 expert's presentation of examples of consummate resemblances between 

 animals' costumes and certain of their backgrounds. It has greatly 

 surprised us that so many people have so slightly noticed the facts 

 revealed as to take them for illustrations of a supposed " theory." The 

 facts, themselves, are what we present. 



From now on I shall be delighted to show to all comers to Monad- 

 nock the perfect background-counterfeiting powers of all sorts of 

 gorgeous birds and butterflies. I have already prepared good fac- 

 similes of a zebra and the head of an oryx, to show the truly wonderful 

 way in which when looked at from a creeping lion's or leopard's eye-level 

 these animals pass for mere sky-vistas through the reeds or branches. 

 My Washington deer was merely a crude beginning of the exhibitions 

 that I can already give of this type of concealing-costume. 



Any child who has access to a wide, open field away from lights can 

 prove for himself that white does not show against a starlit night sky. 

 And it is only fair to point out that any one so ignorant of the simplest 

 laws of optics as to share the popular notion that it does, is not compe- 

 tent to testify in this matter. Let the experimenter hold up between his 

 eye and a clear, moonless night sky, a white card so inclined as to permit 

 him to see its upper side. 7 Even in a wide, open field he can at most 

 make it come as bright as the sky beyond it, and consequently vanish; 

 but it can not of course get brighter than the sky. How could it, since 

 it owes all its light to this very sky ! Yet Eoosevelt says : " At night, 

 in the darkness, . . . the white rump-mark of the antelope is almost 

 always the first thing about them that is seen, . . . and at night it does 

 not fade into the sky, even if the animal is on the sky-line." 



Many persons who hear of the vanishing-power I show in the 

 brilliant bird-skins and butterflies and these white-topped animals sug- 

 gest that in the animals' homes all might be different. I need only 

 answer that when they see the vast range and astounding precision of 

 what I show, this fear will vanish. The evidence is literally over- 

 whelming. It is in every case only against a background notably like 

 that of the animal's home that he will vanish. 



6 ' ' Concealing Coloration in the Animal Kingdom. ' ' 



7 Moonlight, of course, or the uneven illumination from a cloudy sky, can 

 make white show momentarily brighter than the sky; but nature has to deal in 

 averages, and these very irregularities of illumination cause the prongbuck's 

 white just as often to look too dark as too light. 



Contradicting what he says of the skunk's white, Colonel Eoosevelt says: 

 "After nightfall the zebra's stripes would be entirely invisible." Here again 

 he is completely wrong, as if he had never hunted by night. These stripes are 

 invisible at night until the enemy is near enough to endanger the zebra. Looked 

 at as near as this, all colors except white, show strongly against a starlit sky. 



VOL. LXXIX. — 3. 



