Slowly the proud crest, standing erect in four straight blades, acquires consistency and colour. The latter turns the requisite shade on the following day. For the first time the wings fold like a fan and lie in their places; the wing-cases lower their outer edge and form a gutter which falls over the sides. The transformation is finished. All that remains for the big Locust to do is to harden his tissues still further and to darken the grey of his costume while revelling in the sun. Let us leave him to enjoy himself and retrace our steps a little. The four stumps, which issued from their sheaths shortly after the corselet split its keel down the middle, contain, as we have seen, the wings and wing-cases, with their network of nervures. This network, if not perfect, has at least the general plan of its numberless details mapped out. To unfurl these poor bundles and convert them into generous sails, it is enough that the organism, acting in this case like a forcing-pump, should shoot a stream of humours, which have been kept in reserve for this moment, the hardest of all, into the little channels already prepared for their reception. With the channel marked out in advance, a slight injection is sufficient to explain the rapid spread. But what were the four strips of gauze while still contained in their sheaths? Are the wings spatules and the three-cornered pinions of the larva moulds whose creases, corners and sinuosities shape their contents in their own image and weave the tissues of the future wing and wing-case? If we had to do with a real instance of moulding, our brains could call a halt. We should say to ourselves that it was quite simple for the thing moulded to correspond with the shape of the mould. But our halt would be short-lived, for the mould in its turn would want explaining: we should have to seek for a solution of its infinite intricacies. Let us not go so far back; we should be utterly in the dark. Let us rather keep to facts that can be observed. I examine through the magnifying-glass a pinion of a larva ripe for transformation. I see a bundle of fairly thick nervures radiating fanwise. Other nervures, paler and finer, are set in the intermediate spaces. Lastly, the fabric is completed by a number of very short transversal lines, more delicate still and chevron-shaped. This, no doubt, gives a rough outline of the future wing-case; but how different from the mature structure! The arrangement of the radiating nervures, the skeleton of the edifice, is not at all the same; the network formed by the transversal veins in no way suggests the complicated pattern which we shall see later. The rudimentary is about to be succeeded by the infinitely complex, the crude by the exquisitely perfect. The same remark applies to the wing-spatule and its outcome, the final wing.