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THE AMERICAN MUSEUM JOURNAL 



of big mammals (not to mention many 

 thousands of birds). I have found by 

 indefinitely repeated experience that if 

 I was entirely motionless I was very 

 rarely observed; but that, no matter 

 how carefully I chose a concealing col- 

 oration for my clothes, I was almost 

 invariably revealed by motion— cer- 

 tainly by anything excepting stealthy 

 motion— if within ken of the animal's 

 vision. (In my writings I explicitly 

 state that in order that concealing col- 

 oration may actually conceal an ani- 

 mal, there must be either lack of mo- 

 tion or stealthy movement.) 



But there is no need to go after big 

 game to test this fact. In the woods 

 near my house wood frogs are common. 

 I almost never see them unless they 

 Jump, and at the end of the first Jump, 

 when my attention has simply been 

 attracted by the motion, I usually lose 

 sight of the frog ; but by moving around 

 in the neighborhood I make it reveal 

 itself by another Jump, which I follow 

 with my eye so that at its end I am 

 usually enabled to place the frog. It is 

 practically invisible when still, thanks 

 to its color, and without regard to its 

 color it is instantly seen when it moves. 

 I am almost ashamed to have to recite 

 such an "experiment" ; a child of six 

 who has been in the woods ought al- 

 ready to understand its truth. I shall 

 quote a far keener and more experienced 

 observer than I am. Mr. William 

 Beebe,^ speaking of the creatures of the 

 tropic forests, says that "one of the 

 most pronounced laws of the Jungle"' is 

 that "the operation of protective colora- 

 tion" depends entirely on immobility. 

 "Clad in white, or in any conspicuous 

 color, you may successfully hunt the 

 wariest of Jungle creatures, provided 

 you select some suitable spot and remain 

 quiet. Garbed in leaf green and the 

 most invisible of khaki, the common 

 agouti and the trustful trumpeter bird 

 will easily escape you if you persist in 



^ Ornithologist at the New York Zoological Park. 

 Author of Tropical Wild Life in British Guiana, 

 from which the quotation following is taken (p. 73). 



walking about or moving some part of 

 your body or hands." 



Professor Longley's thesis is that 

 there is no warrant for belief in the 

 existence of "conspicuousness of ani- 

 mals of high color," and he in effect 

 denies "that there are con.spicuous ani- 

 mals," and states that what he believes 

 he has shown to be true of one group of 

 fishes is inconsistent with the assump- 

 tion that animals of high color "pos- 

 sess more than minimal conspicuous- 

 ness under natural conditions." The 

 marvelous logic of this last proposition 

 is that the existence of concealing col- 

 oration on certain fishes is inconsistent 

 with the assumption that such utterly 

 different animals as ravens, flamingos, 

 white pelicans, sable antelopes, white 

 goats, and black squirrels with white 

 tails "possess more than minimal con- 

 spicuousness under natural conditions." 

 He announces the "essential truth" of 

 Mr. Thayer's "hypothesis of concealing 

 coloration." ^ 



Mr. Thayer's book^ deals mainly 

 with mammals and birds. Dewar and 

 Finn in their capital book deal mainly 

 wath mammals and birds. I specifi- 

 cally stated that what I said referred 

 only to mammals and birds. Long- 

 ley's observations refer only to reef 

 fishes. Thayer states that all animals 

 which ever are prey or are preyed on 

 (which means virtually all) are con- 

 cealingly colored, coloration being a 

 survival factor produced by natural se- 

 lection ; and the great majority of his 

 illustrations and examples are drawn 

 from among birds and mammals, as to 

 which two classes he specifically and 

 sweepingly lays down his— imaginary 

 —law. I state that as regards birds 



- The Laiv that Underlies Protective Coloration, 

 Abbott H. Thayer, The Auk, Volume XIII, 1896, 

 and Smithsonian Yearbook, 1898. Thayer's hy- 

 pothesis states that animals are "countershaded," 

 painted by nature darkest on those parts which 

 tend to be most lighted by the sky's light and vice 

 versa, and that this causes them to disappear, 

 their colors and patterns becoming pictures of 

 such background as one might see if the animal 

 were transparent. 



^ Concealinfi Coloration in the Animal Kingdom, 

 being a summary of Abbott H. Thayer's discov- 

 eries. By Gerald H. Thayer. The Macmillan Co., 

 New York, 1909. 



