108 A. S. PEARSE 



their own. A walking-stick will maintain a difficxilt attitude for 

 a long time rather than disclose its presence by the slightest 

 movement, thus indicating by its reactions that it has some 

 recognition (not necessarily recognition on the part of the indi- 

 vidual, but recognition at least so far as the race is concerned) 

 that it is protected, but it takes no cognizance of color. Further- 

 more, Schleip ('lo) has shown that the color changes of the 

 walking-stick have no relation to the color of the environment, 

 but are induced chiefly by light. 



Adaptation. — Thayer ('09) would have us believe that all 

 animal coloration is protective (concealing) ; not necessarily at 

 every moment of an animal's life, perhaps only at some infre- 

 quent moment of great need. His arguments are very convincing 

 and many of his conclusions seem quite probable. If the Misu- 

 menas described in this paper are used as an illustration, we 

 can readily imagine that the presence of two color varieties 

 which resemble the commonest flowers might be a valuable 

 asset in the struggle for existence. Yellow or white flowers 

 grow together in great fields and a spider would often find a 

 suitable color background if it were in the proper habitat. It 

 is possible that more yellow spiders are hatched year after year 

 in large patches of goldenrod, and that white spiders are cor- 

 respondingly more abundant where boneset abounds, but we 

 can only surmise this, for nothing is known of the heredity 

 of color in spiders, nor how much they wander from field to field. 

 At any rate, if natural selection, having only two choices, picked 

 out yellow and white to match the greatest number of flowers, 

 it could not have chosen two colors that would be better for 

 the locations where Misumena abounds. 



We have many striking instances of extremely refined pro- 

 tective resemblances among the arthropods; examples like 

 Kallima, Misumena and the walking-stick are familiar to every 

 naturalist. Beddard ('92) mentions a spider which was so like 

 a mass of bird excreta that it deceived the eye of a trained 

 observer. Beebe ('09) in speaking of the mangrove crab says, 

 "he grew to resemble his home root," and dwells at some length 

 on the variety of mangrove roots and the accuracy with which 

 the crabs imitate the patterns they present. Examples of this 

 kind might be multiplied. 



In speaking of insects, Kellogg ('05, p. 613) says, "natural 



