A BED OF NETTLES. 121 



leaf is very common among all those plants 

 which spring up beside the hedgerows in the 

 same erect shrubby manner as the nettles. 

 It is almost exactly imitated in the dead- 

 nettle and the hemp-nettle, which are plants 

 of a totally distinct family, with flowers of the 

 sage and rosemary type ; and it is more or 

 less simulated by ten or twenty other species 

 of like habit. This peculiarity of external 

 resemblance, under identical circumstances, 

 between organisms wholly unlike in origin 

 and pedigree, is a common and natural one. 

 Thus, in the dry deserts of India, some of 

 the spurge tribe grow thick and succulent, so 

 as exactly to resemble the genealogically very 

 ^different cactuses of like dry deserts in 

 America ; and a gallinaceous bird, stranded 

 on the shores of the Antarctic Islands, has 

 acquired the long legs of the waders, together 

 with the characteristic colours of the gulls. 

 Whatever the original stock, natural selection 

 tends always under like circumstances to pro- 

 duce like results. 



