3 o THE POPULAR SCIENCE MONTHLY 



demand a " clean chipmunk " — i. e., an «w-counter-shaded and wn-dead- 

 leaf-colored one — when the little beast dodges him. Note, too, that a 

 grass-stained ball against the grass is, at its worst, far more conspicuous 

 than an average chipmunk against the leaves, because the ball turns 

 over, and therefore could not be counter-shaded. (Note also that pred- 

 ators in general are believed to miss far oftener than they succeed.) 



Many familiar experiences prove this fact, that one's power to catch 

 or hit a moving object depends on the distinctness with which one sees 

 it. The more brilliantly a dodging object shows against the background, 

 the more promptly can the brain of the pursuer command the corre- 

 sponding movement. Those who have tried to catch butterflies, house- 

 flies or mosquitoes, on the wing, or shoot a flying bird, either know this 

 by heart or will realize it the moment they try it again. When a dark 

 fly passes a dark space, to make sure of him you wait till he gets 

 against a Ugh t space, and a shooter does the same with a bird. Through- 

 out all nature animals' coloration proves to be such as minimizes, in the 

 most wonderful way, to the eyes of their pursuers, their visibility when 

 in motion. And in missing this fact" Colonel Eoosevelt has missed a 

 vast part of the whole wonderful subject. So true is it that, as he says, 

 motion almost ensures detection, that it is no wonder we find concealing- 

 coloration by far most constantly needed and at work — making the 

 wearer as hard as possible to catch — where there is pursuit and flig\t. 

 This matter would come home clearly to Colonel Eoosevelt if he would 

 try to hit a concealingly counter-shaded moving target against a back- 

 ground that it matched, and see what kind of a score he could make 

 compared to what he could do with an un-countershaded one. 



As soon as the public have been shown the astounding concealing- 

 power of those African animals' reed-and-sky counterfeits, such as the 

 zebra's and oryx's — which make it as hard as possible, by night as well as 

 by day, for the springing feline to distinguish between starting zebra 

 and jostled reeds — they will begin to see how complete has been their 

 misconception of this matter. And the moment they see a demonstra- 

 tion of the magical working of facsimiles of these animals amidst reeds 

 and branches, out-of-doors, they will see at a glance that it would be 

 just so anywhere in the world. Colonel Eoosevelt has confounded detec- 

 tion with catching. There is a vast difference. Every animal that has 

 lived a year or two has been detected — how many thousand times — by 

 other animals that would gladly have caught him ; yet there he still is ! 

 Detection means, in some cases, much; but in far more case it means 

 little. As Eoosevelt evidently thought about the plains game, out in the 

 open detection is nothing to them. He is also right when he says that 

 these animals, zebras for instance, are sure to be observed by the 

 ambushed lion as they nervously troop down to drink. The reader 

 shall see how wonderfully their case bears out the hypothesis that all 



