VII 
THE COLOURS OF THE LEPIDOPTERA 
161 
Pigments and Mimicry 
Mr. Hopkins notes in relation to the question 
of mimicry that the pigments of the Heliconidae 
are not the same as those of the Pieridse, for though 
soluble in water they do not give the murexide 
reaction. He regards this as evidence against the 
views of those who hold that the resemblances of 
mimicry may be due to relationship between the 
forms. We do not propose to discuss the question 
of mimicry here, but may just note that mimicked 
species usually display what are known as “ warning 
colours,” which apparently, in butterflies at least, are 
always pigmental colours, or the simple types of 
optical colour like white and black. Now as there 
are in butterflies, apart from structural colours, only 
about three pigments to choose from (yellow, red, 
brown, and rarely green), the range, if we may 
so speak, is somewhat limited. Apart from the 
question whether the presence of the yellow and 
red pigments in considerable amount is not a sign 
of little specialisation, the frequent absence of 
structural colour from these “ warning ” forms is at 
least probably such a sign. Instead therefore of / 
supposing that the Heliconidae have, in Mr. Wallace’s 
words, “ acquired lazy habits ” and a slow flight 
because they are uneatable, and the Pieridae because 
they resemble the Heliconidae, may we not rather 
suppose that the slow flight and “ warning ” colours 
in both cases are due to the same cause, the 
relatively low organisation which renders pigmenta¬ 
tion by waste products possible, which makes brilliant 
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