A Turn-Coat of the Woods 



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under proper conditions, do not always behave 

 as the physiologist thinks they should. There 

 is no doubt that in many cases the changes of 

 color are not voluntary, but reflex actions. It 

 is quite conceivable that the sensation of sitting 

 on a rough surface starts a whole train of proc- 

 esses : roughness means bark, bark is brown, 

 change into brown; but one and the same tree- 

 frog does not always assume the color of the 

 bark when it rests, or even sleeps, upon such a 

 piece. He will, if it suits him, remain grass- 

 green upon a yellow stone, or on a white window- 

 frame. I purposely describe such conditions, 

 changes, coincidences and discrepancies, in vari- 

 ous species, notably in Hyla arborea, H. cceru- 

 lea, Rana temporaries, Bufo viridis, to show that 

 in many cases the creature knows what it is 

 about, and that the eye plays a very important 

 part in the decision of what color is to be 

 produced. The sensory impression received 

 through the skin of the belly is the same, no 

 matter if the board be painted white, black, or 

 green, and how does it then come to pass that 

 the frog adjusts its color to a nicety to the 

 general hue or tone of its surroundings ? " 



Whether or not the little animal makes this 

 change knowingly, sometimes doing it almost 



*>$ 223 5* 



