68 STRICTLY INCOG. 



distinctness of the mimicliers and the mimicked was satis- 

 factorily settled. Scarcely less curious is the case of Mr. 

 Wallace's Malayan orioles, two species of which exactly 

 copy two pugnacious honey- suckers in every detail of 

 plumage and coloration. As the honey-suckers are avoided 

 by birds of prey, owing to their surprising strength and 

 pugnacity, the orioles gain immunity from attack by their 

 close resemblance to the protected species. When Dr. 

 Sclater, the distinguished ornithologist, was examining 

 Mr. Forbes's collections from Timorlaut, even his experi- 

 enced eye was so taken in by another of these decep- 

 tive bird-mimicries that he classified two birds of totally 

 distinct families as two different individuals of the same 

 species. 



Even among plants a few instances of true mimicry 

 have been observed. In the stony African Karoo, where 

 every plant is eagerly sought out for food by the scanty 

 local fauna, there are tubers which exactly resemble the 

 pebbles around them ; and I have little doubt that our 

 perfectly harmless English dead-nettle secures itself from 

 the attacks of browsing animals by its close likeness to the 

 wholly unrelated, but well-protected, stinging-nettle. 



Finally, we must not forget the device of those 

 animals which not merely assimilate themselves in colour 

 to the ordinary environment in a general way, but have 

 also the power of adapting themselves at will to whatever 

 object they may happen to lie against. Cases like that of 

 the ptarmigan, which in summer harmonises with the 

 brown heather and grey rock, while in winter it changes to 

 the white of the snow-fields, lead us up gradually to such 

 ultimate results of the masquerading tendency. There is 

 a tiny crustacean, the chameleon shrimp, which can alter 

 its hue to that of any material on which it happens to 



