3i6 
COLOUR IN NATURE 
CHAP. 
forward some new facts of great interest in this 
connection. Piepers opposes altogether the idea of 
the action of Natural Selection in the matter, and 
remarks that the idea that the phenomenon is main¬ 
tained by the accruing practical profit to the organism 
is one “ essentially English.” 
i. Mimicry .—As is well known, the doctrine of 
mimicry among butterflies involves primarily the 
hypothesis that birds are the great enemies of 
diurnal butterflies, that certain families of butterflies, 
notably the Heliconidae, the Danaidse, and the 
Acraeidae, are not attacked by birds, and that there¬ 
fore wherever these butterflies occur they are 
mimicked by non-protected butterflies. Piepers 
attacks the prime proposition that birds are the 
great enemies of butterflies, and then discusses in 
detail some of the so-called examples of mimicry. 
As to the first point, it is admitted on all hands 
that the night-flying Lepidoptera are constantly eaten 
by birds, but with regard to the diurnal forms the 
question is different. Observations as to the actual 
pursuit of butterflies by birds are exceedingly few, 
although Bates and Wallace speak of finding scattered 
wings in the forest. M. Piepers, during more than 
thirty years’ observation in India and the Malay, saw 
one or two isolated cases only, and he quotes other 
observers (Pryer, Skertchly, Scudder) as being equally 
or more unfortunate. As a whole, he concludes that 
although some birds may occasionally eat diurnal 
butterflies, there is as yet no evidence of that habitual, 
unvarying persecution which the theory of mimicry 
demands—a conclusion which is somewhat surprising 
to the outsider. 
