82 THE POPULAR SCIENCE MONTHLY. 



panying these, a few individuals of rare species, themselves de- 

 fenseless and palatable, differing widely from the type of the 

 genera to which they belong, and so closely resembling the others 

 as to be readily mistaken for them even by experienced collectors. 

 Since its discovery, numerous examples of this so-called " mim- 

 icry " have been brought to light in many classes of animals, its 

 conditions being always the same. A rare, helpless species is pro- 

 tected from attack by similarity, in external appearance only, to 

 a common, easily recognizable, well-defended one. 



There are strong resemblances between widely separated gen- 

 era of plants. The submerged parts of water-crowfoots are much 

 like those of water-marigolds. " It is almost impossible to distin- 

 guish between " the euphorbias of Africa and the cacti of South 

 America, when not in blossom ; mare's-tail looks like an equise- 

 tum — one is a flowering, the other a flowerless plant ; the false 

 goat's-beard closely resembles the true ; dalibarda " in aspect and 

 foliage resembles a stemless violet." Observation may find proof 

 of some advantage gained to the feebler plant by the likeness in 

 the last two cases, inasmuch as the plants occupy the same locali- 

 ties, and in each case one of the species is much more limited in 

 distribution than the other. But none of the others are examples 

 of true mimicry, because the similar plants do not inhabit the 

 same regions, and it is hardly supposable that any benefit accrues 

 from the likeness. Similarity of conditions may have much to 

 do with it in some instances, but a deeper cause, and one of a kind 

 which we can not yet conceive, must be sought in explanation of 

 the extraordinary results sometimes reached. 



Nevertheless, there is true mimicry in plants. 



The only South African balsam is strikingly like an orchid 

 which grows in the same locality and is visited by the same in- 

 sects ! Surely a clear case of plagiarism. 



The " cow- wheat " is parasitic upon the roots of wheat, whose 

 seed its own so exactly resembles that the two can only be distin- 

 guished by careful botanical examination. So the husbandman 

 who himself sows tares among the wheat, one day wakes to say, 

 " An enemy hath done this." 



Sir John Lubbock thinks that the harmless dead-nettle may 

 be protected from grazing cattle by its great likeness to the sting- 

 ing nettle — a member of a widely different order. 



In 1833 Robert Brown conjectured that the remarkable insect- 

 like forms of the flowers of the genus Ophrys (bee orchid, etc.) 

 " are intended to deter, not to attract insects." But Darwin has 

 shown that some of the species are self-sterile, and all of them 

 are constructed as though insects had played an important part 

 in the shaping of the floral organs. The native home of the genus 

 is the Mediterranean region, where all kinds of methods of defense 



