REVIEWS. 
222 
By what means, it may be asked, have so many butterflies of the 
Amazonian region acquired their deceptive dress ? Most naturalists 
will answer that they were thus clothed from the hour of their 
creation—- an answer which will generally be so far triumphant that 
it can be met only by long-drawn arguments ; but it is made at the 
expence of putting an effectual bar to all further inquiry. In this 
particular case, moreover, the creationist will meet with special 
difficulties ; for many of the mimicking forms of Leptolis can be 
shown by a graduated series to be merely varieties of one species ; 
other mimickers are undoubtedly distinct species or even dis¬ 
tinct genera. So again, some of the mimicked forms can be shown 
to be merely varieties ; but the greater number must be ranked as 
distinct species. Hence the creationist will have to admit that some 
of these forms have become imitators, by means of the laws of varia¬ 
tion, whilst others he must look at as separately created under their 
present guise; he will further have to admit that some have been 
created in imitation of forms not themselves created as we now see 
them, but due to the laws of variation ! Prof. Agassiz, indeed, would 
think nothing of this difficulty; for he believes that not only each 
species and each variety, but that groups of individuals, though iden¬ 
tically the same, when inhabiting distinct countries, have been all 
separately created in due proportional numbers to the wants of each 
land. Not many naturalists will be content thus to believe that 
varieties and individuals have been turned out all ready made, 
almost as a manufacturer turns out toys according to the temporary 
demand of the market. 
There are some naturalists, who, giving up to a greater or less 
extent the belief of the immutability of species, will say that as the 
mocked and mocking forms inhabit the same district, they must have 
been exposed to the same physical conditions, and owe to this circum¬ 
stance their common dress. What direct effect the physical conditions 
of life, that is, climate with all its contingencies and the nature of the 
food, produce on organic beings is one of the most abstruse problems 
in natural history, and cannot be here discussed. But we may remark 
that when a moth closely resembles a butterfly, or better still, when 
a cricket resembles a Cicindela, it becomes very difficult to believe 
that insects so widely dissimilar in their internal structure and habits 
of life, should have had their external organization alone so largely 
influenced by their conditions of life as to become almost identical 
in appearance. Can we believe that one insect comes to resemble 
the bark of a tree ; another a green leaf; another in its larval condi¬ 
tion the dead twig of a branch; or that a quail or snipe comes to 
resemble the bare ground on which it lies concealed, through the 
direct action of the physical conditions of life P If in these cases, we 
reject this conclusion, we ought to reject it in the case of the insects 
which mock other insects. 
Assuredly something further is required to satisfy our minds: 
what this something is, Mr. Bates explains with singular clearness 
