sage INTRODUCTION 
As already explained in an earlier chapter (see p. 124) the colour-sense is 
also particularly well developed in butterflies :—/here ts certainly a remarkable corre- 
spondence as to colour between some flowers and the Lepidoptera which vistt them. 
Hermann Miller (Kosmos, iii, 1878, p. 418) gives the following additional examples 
of this:—The orange-hued Composites Crepis aurea, Hieracium aurantiacum, and 
Senecio abrotanifolius, are a veritable playground in sunny weather for butterflies 
of fiery-red colour (Argynnis Aglaja, Polyommatus Virgaureae, P. hippothde var. 
eurybia). Hermann Miiller saw the two copper butterflies (Polyommatus) in 
question and Argynnis pales flying repeatedly even to the bright red fruits of Rumex, 
and Blues (Lycaena) settling with unmistakable preference on the blue capitula 
of the alpine species of Phyteuma. He is, therefore, inclined to think that the 
same ‘preference of butterflies for certain colours, as expressed in their own 
adornment, which has been acquired by sexual selection, has also determined their 
choice of flowers, and therefore, indirectly, the colour of lepidopterid flowers, as 
also the surprising resemblances existing between the odours of butterflies and 
those of the blossoms they pollinate.’ 
A case of protective resemblance described by E. Kéhne (Verh. bot. Ver., 
Berlin, xxviii, 1886, pp. 6-7) may be appropriately given here as a final illus- 
tration of the above principle. This observer noticed, not far from Wangerin 
in Pomerania, a very large number of male and female brimstone butterflies 
(Rhodocera Rhamni Z.) on the pale capitula of the cabbage thistle (Cirsium 
oleraceum JZ.). In the position of rest the butterfly held its wings vertically, so 
that their under-sides alone were visible, and these, especially in the rather whitish 
female, harmonized so remarkably with the colour of the capitulum and its involucre 
that when the light was bright not the slightest difference of hue could be perceived. 
And it must be added that the involucral bracts project to some extent above the 
capitulum, and that the shape of the resting butterfly, as determined by its pointed 
wings, obviously simulates that of the upwardly directed points of the bracts. 
Even the clear veining of the under-sides of the wings forcibly reminds one of 
that of the leaves. In fact, the form and colour of the capitula and involucres 
agreed so closely with those of the butterfly, when seen in the glaring sunshine, 
that Kéhne could not distinguish with certainty, even from a very small distance, 
whether or no a brimstone butterfly was resting on a given capitulum, and he 
did not usually perceive the insect till it flew off on his approach. He regards 
this remarkable colour-agreement between butterfly and plant as a mutual adapiation. 
When on the wing, this butterfly, like most others, is protected from the attacks 
of enemies by its erratic, undecided, devious flight; if at rest it is never better pro- 
tected than when it has settled on the yellowish capitulum. In places where 
Cirsium oleraceum grows, it will therefore be able to maintain itself in large numbers, 
and will consequently leave numerous offspring. The plant, on the other hand, 
is assured of many visits from the insect, and hence of amply sufficient pollination 
and seed-production. It too is, therefore, able to multiply to an unusual 
extent. 
The significance of the individual groups of insects, with reference to the 
pollination of flowers, has already been dealt with by Hermann Miiller, who has 
also given an exhaustive account of their structural peculiarities, so far as they are 
