44



Dr. Arthur G. Butler,



shaded spots, and the three outermost of a series of black undulated

lines which cross the disc of the wings (see my ‘ Lepidoptera Exotica,’

pi. xxx); the ocellus in the front wings of the butterfly genus

Mesosemia and towards the posterior angle of the hind-wings of many

of the Small Blues ( Lyccenidce) seem to have originated in the same

way; though it is possible that the black zone or iris enclosing the

pupil in these and many other groups (notably the Ringlets ( Satyrince >

may have originated, as Darwin suggests (p. 654), “ by the colouring

matter being drawn towards a central point from a surrounding zone,

which latter is thus rendered lighter” ; but this does not explain the

central white pupil or pupils, or the sometimes variously coloured

concentric circles enclosing the iris.


Many years ago I made experiments in dyeing butterflies; in

some cases I first soaked the wings in hot water, in which I had

dissolved washing-soda ; the latter united with the somewhat greasy

pigment, so that it was washed out of most of the scales, leaving

them almost colourless ; some of the white scales, however, seem to

have been hermetically sealed instead of open at the extremities, so

that when the wings were dyed individual white scales remainedr

giving a marvellously natural appearance to these faked specimens,

even when examined through a lens. Some dealers who saw them

were much exercised in their minds as to the possibility that dis¬

honest persons might, if they knew the process, pass off similarly

dyed specimens as extraordinary aberrations. Is it not possible that

these white scales may be solid throughout, not sac-like as in the

normal type, in which case the dark colouring could not affect

them ?* With regard to the concentric rings I have little doubt that

they originated from parallel lines approximate to the ocelli. In

many examples, especially among the Satyrine butterflies, some

or all of these ocelli are represented by the white pupils alone, and

in some there are gradations from the latter to the perfected eye-spot.


Central white or coloured spots in the feathers of birds have

clearly been formed by the inward expansion of the submarginal or

marginal borders. Turning to the illustration of a hybrid Grass-

finch (‘ Avic. Mag.,’ n.s. vol. iv, October, 1906) we observe that the



* In some of the silk-moths (Saturniidce) the pupil of the ocellus is represented

by a colourless, transparent, chitinous disc.



