COLORATION 69 



gray or white may each in turn be more conspicuous or 

 less conspicuous than any of the others. But half of 

 the hours of darkness are moonlit, and if the moon is 

 very bright, white, black, and the bold colors generally, 

 are almost as visible as by day. Taking into account 

 moonlit and moonless nights, starlit and starless nights, 

 clear and stormy nights, and all the different cloud effects, 

 and the probable backgrounds of sky, soil, and vegetation, 

 white is on the average by all odds the most conspicuous 

 color at night, and the neutral tints, the dull grays, drabs, 

 and yellow — browns are the least conspicuous when seen 

 from tht ordinary view-point of the ordinary foes. The 

 white rump of a standing or running prongbuck or black- 

 tail deer or bighorn is under most conditions of a highly 

 revealing or advertising value at night as well as by day; 

 and the same is true of a running white-tail deer or rabbit. 

 We state this as the result of innumerable personal observa- 

 tions of these animals when in their own homes under nor- 

 mal conditions. 



Two of Mr. Thayer's "proofs by experiment" may be 

 mentioned to illustrate the worthlessness of experiments 

 when carried on under the influence of a perverse obsession. 

 Mr. Thayer's thesis is that all forms of coloration are con- 

 cealing; but next to countershading he considers **ruptive" 

 and "secant" coloration schemes as most potently con- 

 cealing. He regards vertical striping as a type of concealing 

 coloration of peculiar potency, brought about purely by the 

 "omnipotent" power of natural selection, because of its 

 survival value. He adduces the striped African antelopes 

 (all of them tragelaphs, except one duiker) as cases in point. 

 He records one experiment which he asserts proves the truth 



