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probability attributed, not to the direct influence of their 
surrounding conditions, but to the advantage they gain from 
concealment whether from enemies or from prey within their 
respective environments, their community of coloration being, to 
use Prof. POULTON's term, syneryptic. But though Mr. ABBOTT 
H. THAYER, who surveys the subject from the point of view of 
an artist, maintains that the variegated patterns of the Butterflies 
in question similarly aid concealment, I do not think that natur- 
alists in general will find his arguments on this head convincing. 
At any rate his contention does not accord with my own experience 
in the tropics. But even if his theory be sound with regard to 
Butterflies, it will not account for the resemblance of a Moth to a 
Hornet, or of a two-winged Fly to a Carpenter-bee. It will scarcely 
be denied that both Hornet and Carpenter-bee are even aggressively 
conspicuous. And what are we to say to the case of a Locustid, 
which is, so to speak, painted to look like an Ant, or to that of a 
Membracid, which screens itself beneath a sculptured representation 
of a similar model? These are not cases of syneryptic modification ; 
nor is it conceivable that the direct influence of external condi- 
tions, even if they are similar (which may be doubted), can impose 
a deceptive picture or piece of sculpture upon the body of an 
otherwise unaltered Insect. Take again the case of a Butterfly like 
Papiliodardanus,the subject of female polymorphism. Community 
of external conditions can scarcely be appealed to in order to 
explain the likeness between each form of the female and a distinct 
species of Danaine, when the individuals of the same brood of the 
Papilio, all presumably exposed to the influence of identical con- 
ditions, have diverged along these three or four different channels. 
Taking all the facts into consideration, we must, I think, conclude 
that the influence ofa common geographical environment, whether 
its influence be directly or indirectly exercised, fails to explain the 
phenomena of mimicry. 
A view that has often been put forward, and maintained with 
great ability, attributes these resemblances to internal causes, which 
compel various species to pass through similar phases of develop- 
ment. These phases, it is held, must from time to time coincide, 
and so we may get between distinct forms a correspondence in 
aspect, which will present the appearance of mimicry. As a rough 
illustration of this view we may suppose a series of kaleidoscopes, 
each furnished with a similar set of fragments of glass, and all 
undergoing rotation together. From time to time it may no doubt 
happen that the patterns shown by two or more of the instruments 
