34 Transactions of the [Sess. 



ance unlike tliat belonging to its own class, and like that of another 

 class, — such resemblance, further, being ostensibly adapted to sub- 

 serve some useful purpose, whatever that purpose may be. This 

 phenomenon has hitherto been investigated to a much greater 

 extent in the Animal Kingdom than amongst plants. Mr H. W. 

 Bates, who first introduced the subject to public notice, and subse- 

 quently Mr Alfred R. Wallace, have both been diligent workers in 

 this interesting field, and many curious facts have already been 

 brought to light. It may perhaps tend to a clearer understanding 

 of the subject in hand — viz., mimetic resemblances in plants — if a 

 glance is taken at some of the analogous conditions which obtain 

 in the Animal Kingdom. 



Among the many ways by which quadrupeds, birds, and insects 

 are believed to maintain their existence is that of concealment by 

 obscure or imitative tints or colours. On this theory an explana- 

 tion is given of wild Rabbits always having grey or brown tints ; 

 of arctic animals possessing white fur; of desert animals being 

 desert-coloured ; and of the desert birds of Asia and Northern 

 Africa — such as the Stonechats, Larks, and Quails — being tinted 

 and mottled to resemble the soil of the districts where they are 

 found. Taking an example or two from the birds of our own 

 country, we at once call to mind the Ptarmigan, with its white 

 plumage in winter and its pearly-grey svimmer dress, harmonising 

 with the lichen-covered stones where it is generally found. The 

 Woodcock is a still better example of imitative tints, in tlie browns 

 and yellows of fallen leaves being reproduced in its plumage, and 

 rendering its resting-place under trees such a safe one. But these 

 resemblances are perhaps found to their greatest extent in the 

 insect world. Mr Wallace, in his ' Contributions to the Theory of 

 Natural Selection,' tells us that " in the tropics there are thou- 

 sands of species of insects which rest during the day, clinging to 

 the bark of dead or fallen trees ; and the greater portion of these 

 are delicately mottled with grey and brown tints, which, though 

 symmetrically disposed and infinitely varied, yet blend so com- 

 pletely with the usual colours of the bark, that at two or three feet 

 distance they are quite undistinguishable." And he remarks further, 

 that these tints of the bark or leaf are not only reproduced in the 

 wings of many insects, but that " the form and veining of the leaf, 

 or the exact rugosity of the bark," are also imitated. The ex- 

 amples of the so-called " Walking -leaf " and "Walking-stick" 

 insects are so familiar, that a passing reference to them will be 

 sufficient. 



Such resemblances, liowever, though undoubtedly something 

 more than mere curious coincidences, are not the only phenomena 

 claiming our attention here. The mimicry of animals which has 

 its fittest counterpart in that of plants is not so much a likeness 



