VARIABLE RESEMBLANCE IN VERTEBRATA. ETC. 109 



Variable Resemblance, Protective and Aggressive 



As in so many other cases, the specialised form of 

 conceahnent by the organism resembling its surround- 

 ings treated of in this chapter may be either Protective 

 or Aggressive ; it may enable an animal to escape its 

 enemies or to approach its prey unseen. Frequently 

 it may be turned to both uses by a single animal. 

 Thus the green tree frog is probably aided in cap- 

 turing the insects on which it feeds because of its 

 close resemblance to the leaves around it ; but it is 

 also protected in the same manner from the animals 

 which prey upon it. Thus Mr. E. A. Minchin tells 

 me, from his experience in India, that tree frogs are 

 sought for with especial eagerness by snakes, which 

 greatly prefer them to others. It is probable that 

 this power when possessed by a vertebrate animal 

 nearly always bears a double meaning, although a con- 

 sideration of the different instances will show that it 

 is especially Protective in some and especially Aggres- 

 sive in others. In the next chapter we shall meet 

 with a large number of cases briefly alluded to at the 

 beginning of this chapter, in which the power is in 

 many respects different, and possesses an entirely 

 Protective meaning. 



