When the whole operation of building is completed, lift up the tumbler, and up will come the saucer too. The two are firmly glued together by the substance secreted; and the power of this as a cementing material will be well illustrated if you endeavour by mere pulling force to separate the two articles. The Puss is not the only caterpillar that works up a foreign material with the contents of the spinning organs. There are several others, in fact, that use for this purpose fragments of wood or other parts of the food plants; and a still larger number bind together leaves, fresh or dead, or particles of earth or other matter. Several such cocoons will be described in our accounts of individual species in another chapter. We shall now devote a little space to a few general remarks on the chrysalides and the final metamorphosis of butterflies and moths. CHAPTER IV _THE PUPA OR CHRYSALIS_ As soon as the last moult of the caterpillar is over, the chrysalis that had already been developing under the cover of the old skin is exposed to full view; and although the perfect insect is not to be liberated for some time to come, yet some of its parts are apparently fully formed. [Illustration: FIG. 30.--THE PUPA OF THE PRIVET HAWK (_Ligustri_).] [Illustration: FIG. 31.--THE CHRYSALIS OF THE LARGE WHITE BUTTERFLY (_Brassicae_).] The newly exposed skin of the chrysalis is very soft and moist, but as it hardens it forms a membranous or horny covering that protects and holds firmly in place the trunk and the various limbs and appendages that are distinctly to be traced on the under surface. If, however, you examine a chrysalis directly after the moult is over, you will often find that the wings, antennae, proboscis, and legs of the future butterfly can be easily separated from the trunk of the body on which they lie by means of a blunt needle, and can be spread out so as to be quite free from that surface. In form the chrysalides of butterflies and moths are as variable as the caterpillars. Many of the former are sharply angular like that of the 'Small Tortoiseshell' already mentioned; but some of the butterflies--the Skippers (page 197)--have smooth and tapering chrysalides, and so have most of the moths. In colour they are equally variable. Some are beautifully tinted with delicate shades of green, some spotted on a light ground, some striped with bands more or less gaudy and distinct, but the prevailing tint, especially among the moths, is a reddish brown, often so deep that it is almost a black. [Illustration: FIG. 32.--THE PUPA OF THE DARK GREEN FRITILLARY (_Aglaia_).] [Illustration: FIG. 33.--THE PUPA OF THE BLACK-VEINED WHITE BUTTERFLY (_Crataegi_).]