MIMICRY 57 
account of this work, the reader is referred to Professor 
Poulton’s recent ‘ Essays on Evolution.’ 
Manystudents of evolution in its more recent develop- 
ments are disposed to attach greater importance than 
does Professor Poulton to the difficulties which beset 
the theory of mimicry, in so far as the theory consists 
in explaining these resemblances by natural selection 
accumulating minute variations in the proper direction. 
Indeed, the power of this evolutionary factor seems 
here to be stretched to its utmost limits of tension. 
The independent evolution of a similar external appear- 
ance has certainly taken place in some cases in which 
any suggestion of mimicry is excluded, and there is 
nothing to prove that colour-patterns of the same type 
may not have arisen from the same causes in widely 
different groups. In cases where the environment to 
which the different forms were exposed was similar— 
as would be the case especially in any single locality— 
such a process of parallel evolution might be thought 
to be all the more likely. 
It is not to be supposed that we intend for a moment 
to impugn the reality of these marvellous resem- 
blances. The smallest acquaintance with the facts 
must show the absurdity of any such suggestion, just 
as the multiplicity of the cases described renders any 
suggestion of coincidence ridiculous. It is only the 
current explanation of these resemblances to which we 
take exception, for the brain reels before the task of 
picturing the gradual building up of such a resemblance 
by the successive additions of small differences, each 
one useful to the possessor of it. 
