The Making of Species 



must be satisfied before such protective mimicry 

 can occur : 



" i. That the imitative species occur in the 

 same area and occupy the same station as the 

 imitated. 2. That the imitators are always the 

 more defenceless. 3. That the imitators are 

 always less numerous in individuals. 4. That 

 the imitators differ from the bulk of their allies. 

 5. That the imitation, however minute, is ex- 

 ternal and visible only, never extending to 

 internal characters or to such as does not 

 affect the external characters." {Darwinism, 

 Chap. ix.). 



Thus the mimic is supposed to deceive his 

 enemies by deluding them into the belief that he 

 is the inedible species which they once tried to 

 eat and vowed never again to touch, so nasty 

 was it. The mimic, then, may be compared to 

 the ass in the lion's skin. Needless to say, this 

 mimicry is quite unconscious. It is supposed 

 to have been developed by natural selection. 

 Every popular book on Evolution cites many 

 examples of such mimicry. We may there- 

 fore content ourselves with mentioning but a 

 few. 



Our common wasps are copied by a beetle 

 (Clytus arietis), active in movement and banded 

 black and yellow, and by several yellow-barred 

 hover-flies (Syrphidae) ; and the bumble-bee 

 by a clear- winged moth (Sesia fuciformis). 



178 



