XXXVill 
Nature.” Applying the preceding observations to the mimicry exhibited by the various 
Pieride (chiefly of the genus Leptalis) of different species of Heliconiide described by 
Mr. Bates, Prof. Westwood contended that Mr. Bates’s supposition that the imitation 
had been assumed by the former in order to enable them to subsist (the Heliconiide 
which possess a strong and disagreeable odour being found to be dominant in South 
America) was not tenable— 
1. Because the mimicking species could barely be said to exist, much less to 
flourish, in the country where the Heliconiide abounded, “ not one in a thousand” 
having been found by Mr. Bates. 
2. Because there still occurred numerous species of white Pieride in the country 
of the Heliconiide in a flourishing condition. 
3. Because there were vast numbers of other groups and species of butterflies in 
Brazil equally subject to attacks of birds with the Pieridw, which had never 
attempted the assumption of forms of the dominant group, Heliconiide. 
4. Because there were great numbers of instances of mimicry between the different 
Heliconiide themselves, which could not have the inducement to mimicry 
attributed to the Pieride. 
Because there were species of Pieride (such as that to which Mr. Hewitson’s 
monstrous individual belonged) of which only one sex mimicked the Heliconiide. 
Tt would require a wide stretch of imagination to suppose that natural selection 
could have led to the assumption of such mimicry by the individuals of only one 
of the sexes of a species.* 
6. Because the theory assumed that the Heliconiide existed before the attempt at 
mimicry commenced on the part of the Pieride ; whereas Mr. Bates’ statement 
would lead to the inference that the Heliconiide were so unstable a group that 
the manufacture of species is still going on among them. 
7. Because, according to the doctrine of chances, it was in the highest degree 
improbable that a casual variation of any given species of Pieride should by 
constant modification, assisted by hereditary descent, gradually assume the form, 
colour and markings of another species, especially of so remarkable a type as the 
Heliconiide. But for an entire group to be simultaneously engaged in such a 
process, each species tending towards distinct and equally peculiar species, would 
by a logician be pronounced impossible. The admission that the God of Nature 
created these species in their present mimetic condition for some wise but hidden 
purpose disposed of all difficulty. 
on 
Mr. Alfred R. Wallace followed, with an exposition of the theory of mimicry or 
adaptive resemblances as explaining anumalies of sexual variation. He began by 
pointing out what was meant by mimicry; when moths or beetles so closely resembled 
the bark of the trees they were accustomed to rest on that it was difficult to distinguish 
them, or when the curious Phasmide were undistinguisbable from the sticks or leaves 
among which they lived, no one doubted that the resemblance was serviceable to the 
creature,—it was a protective adaptation. So with the moths of the genus Trochilium, 
which resembled stinging Hymenoptera, but were themselves helpless sluggish 
* Papilio Cenea exhibts a double system of mimicry, the male resembling Danais 
Echeria and the female Danais Chrysippus! 
: 
