D.—ZOOLOGY. 89 
tional forms appear and, most striking of all, the trophonius female 
mimicking the Danaine D. chrysippus has not been bred but only its 
primitive ancestor lamborni, and this has appeared often, although very 
rare in other localities. Here, too, the same explanation holds, for Dr. 
van Someren and Canon Rogers have observed that for some cause, 
perhaps the elevation, the Danaine models are much scarcer than their 
mimics, and cannot be supposed to influence the selective elimination as 
in other parts. 
These two striking examples offer, I believe, convincing evidence of the 
power of selection in the evolution and preservation of mimetic patterns ; 
also that the evolution was by small variational steps. The remarkable 
families of Hypolimnas bolina, bred by Mr. H. W. Simmonds in Fiji, supply 
further evidence in favour of this last conclusion.‘ 
Admitting, as claimed and, I believe, proved above, that selection is 
essential for the evolution of mimicry, nevertheless the abundance of 
mimetic forms when their models are rare, and still more when they are 
absent altogether, does make it difficult to feel confident that Natural 
Selection, in its accepted sense of survival of the fittest, has always been the 
cause. This doubt was first raised in my mind by the consideration of 
the Oriental butterfly, Papilio polytes, and led to the belief that in this 
and probably other predominant species the absence of the model 
finally leads to the disappearance of the mimetie pattern, ‘ although the 
_ species that bore it remains as abundant as before. The survival or 
extinction of the species is not affected: all that has happened is the 
survival or extinction of a pattern borne by a certain proportion of the 
individuals of the species. When these disappear, other individuals with 
another pattern take their place.’4? For this process Prof. Julian Huxley 
has suggested the term ‘ Intraspecific Selection,’ to be contrasted with 
Natural Selection which ensures the survival of the species in its organic 
environment and, therefore, in a struggle which is interspecific. Mr. 
A. J. Nicholson? has independently proposed a similar hypothesis but 
seeks to carry it much further, so as to cover all examples of Mimicry and 
Protective Resemblance. My reasons for disagreeing with this opinion 
are given in the above-mentioned paper on Intraspecific Selection. 
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Certain criticisms which have been brought against the theory of 
mimicry have followed from the erroneous assumption that the Warning 
Colours of the models imply complete immunity from attack, even by 
parasites, an assumption unfortunately made by Haase in his important 
and valuable work.“ Of course no species enjoys absolute immunity, 
and if it did so the enjoyment would be brief, for it would rapidly destroy 
5 its own means of existence. Furthermore we know, as my friend Dr. Hale 
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| Prans. Ent. Soc. Lond., 1923, pls. XLV-LIIL. 
_ _ * Poulton in Proc. Zool. Soc. Lond., 1928, p. 1037. The term ‘ Intraspecific 
Selection ’ was introduced in this paper, which also quotes the essential passages 
"9 from the paper (Bedrock, vol. ii., No. 3, October 1913, p. 295) in which the hypothesis 
J was first suggested. 
_ __ # *A& New Theory of Mimicry in Insects,’ Australian Zoologist, vol. v., pt. 1, 
_ November 1927, p. 10, pls. I-XIV. 
“ Untersuchungen iiber die Mimicry, Stuttgart, 1891-3. 
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