In a state of nature the butterfly seems little given to variation. In rearing from the caterpillar, however, some curious aberrations occasionally crop up. In my early days of collecting I raised a number of specimens from caterpillars selected from a large brood; every one of these butterflies was of a dull brownish colour and had a greasy semi-transparent appearance. I regret to add that I set them all at liberty as they did not come up to my, then, standard of what a Peacock butterfly should be. Now and then specimens are bred from collected caterpillars, in which the eye spots are represented by a broad white cloud-like suffusion on the fore wings, and by a pale roundish patch on the hind wings; in conjunction with this the black costal spots of the fore wings are all more or less united (see Plate 41). This extreme variety is known in the vernacular as the "Blind Peacock," and as _ab. belisaria_ in science; between it and the typical form there are all kinds of intermediate modifications, and one of these is also shown on the plate referred to. It may be interesting to remark that similar varieties have been produced by subjecting the chrysalids at a particular period to a very low temperature. Readers who may wish to know more about "Temperature Experiments" are referred to a pamphlet on the subject by Dr. Max Standfuss. The egg, an enlarged figure of which will be found on Plate 39, is olive green in colour, and has eight ribs, which start just above the base and turn over the top. The eggs are laid in April or May in batches on the upper part of nettle plants and under the young leaves. The mature caterpillar is velvety black with white dots, and the divisions between the rings of the body are well marked. The spines are black and rather glossy, and besides this clothing, the body is also provided with short hair which gives the velvety appearance. The head and a plate on the next ring, also the legs, are shining black; the prolegs are blackish, tipped with yellowish. When quite young they are greenish-grey, and although hairy are without spines. The caterpillars usually feed in companies in June and July on the common stinging nettle. They have also been found on hop. Once or twice I have reared caterpillars of this butterfly, and also those of the Small Tortoiseshell and the Red Admiral, on hop, but the result has been disappointing, as the specimens produced were always small in size. The individuals for these experiments were obtained from nettle, and were generally about half grown at the time they were put on the hop diet.