CHAPTER VII 



VARIABLE PROTECTIVE BESEMBLANCE 

 IN VEBTEBBATA, ETC. 



Protective Resembjance in its highest and most per- 

 fect form must not be fixed, but capable of adjustment, 

 so that the animal is brought into correspondence 

 with each of the various tints which successively form 

 its environment, as it moves about. An active and 

 wide-ranging animal will be benefited by the power 

 of resembling the tints of many different environments, 

 and by that of changing its colour rapidly. 



More sluggish animals only require the power of 

 bringing their appearance into harmony with a single 

 environment, although the capability of adjustment 

 is still of great value, because the environments of the 

 different individuals vary, at any rate to a slight 

 extent. Thus a moth lays some of its eggs upon one 

 tree of a certain shade of green, and others upon 

 another with leaves of a rather different shade ; so that 

 the caterpillars would not have same environment, and 

 would gain by possessing the power to adapt their 

 colours. At the same time there would be no im- 



