464 Evolution by Segregation . [August, 
C. granulatus is in Lancashire the commonest Carab, but is 
comparatively rare in the south. Farther north C. glabratus 
becomes exceedingly abundant. It would be hard to point 
out, after a careful survey of these inserts, what advantage 
the differences of colour and sculpture between one and 
another of these inserts can be in the struggle for existence, 
— especially as they prey in the night or in the early morning 
twilight, — and hence their origin, either in England or on the 
European continent, can with difficulty be traced to natural 
selection. 
Among the chief evidences of the Darwinian dodlrine are 
the phenomena of Mimetism, which have been so ably ob- 
served and described by Bates, Belt, and others. It is often 
found that certain animals, especially insedts, closely re- 
semble the colour and the texture of the leaves, flowers, 
bark of trees, sand, and other objedfs, animate or inanimate, 
among which they lurk. Such resemblances enable some 
creatures to escape the quest of their enemies, whilst other 
species in the same manner deceive their intended prey. 
About the fadts in question there is no dispute. Before the 
publication of the “ Origin of Species ” they had not escaped 
the notice of naturalists, and, as Herr Wagner tells us, they 
were the subjedt of frequent discussion. The Darwinian 
explanation of the phenomena is perfedfly familiar. It is 
supposed that creatures which were, from their colour and 
make, easily recognisable, being in contrast with the colour 
of their habitat, were, unless otherwise protedted, sifted out, 
— gradually eliminated. Those which closely resembled the 
foliage among which they lived, or the earth on which they 
crept, escaped and perpetuated their species. Let us take 
the case of a sandy desert where every creature, as the Rev. 
Canon Tristram informs us, is “ desert-coloured.” No one 
can deny that a red or a brown insedf would be more easily 
recognised by insedtivorous birds than if it had been of a 
stone- or a dull fawn-colour; and supposing one out of a 
brood of its descendants departed from the heretofore normal 
colour of its race, and approached the universal fawn-tint of 
the locality, it would, pro tanto, be more likely to escape its 
enemies and to survive. Hence it is assumed that by degrees 
the entire population of a desert would have a colouration 
in harmony with the general tone of the scene. 
If the colours and shapes of animals have been modified 
on this principle, then the fadls of mimetism or “ mimicry ” 
must be recognised as forming a powerful argument in favour 
of the formation of species by the process of natural selec- 
tion, Herr Moritz Wagner, however, explains the phenomena 
