Slowly the superb erection composed of the four flat fan-like pinions assumes rigidity and colour.  By to-morrow the colour will have attained the requisite shade.  For the first time the wings close fan-wise and lie down in their places; the elytra bend over at their outer edges, forming a flange which lies snugly over the flanks.  The transformation is complete.  Now the great locust has only to harden its tissues a little longer and to tan the grey of its costume in the ecstasy of the sunshine.  Let us leave it to its happiness, and return to an earlier moment.

The four stumps which emerge from their coverings shortly after the rupture of the corselet along its median line contain, as we have seen, the wings and elytra with their innumerable nervures.  If not perfect, at least the general plan is complete, with all its innumerable details.  To expand these miserable bundles and convert them into an ample set of sails it is enough that the organism, acting like a force-pump, should force into the channels already prepared a stream of humours kept in reserve for this moment and this purpose, the most laborious of the whole process.  As the capillary channels are prepared in advance a slight injection of fluid is sufficient to cause expansion.

But what were these four bundles of tissue while still enclosed in their sheaths?  Are the wing-sheaths and the triangular winglets of the larva the moulds whose folds, wrinkles, and sinuosities form their contents in their own image, and so weave the network of the future wings and wing-covers?

Were they really moulds we might for a moment be satisfied.  We might tell ourselves:  It is quite a simple matter that the thing moulded should conform to the cavity of the mould.  But the simplicity is only apparent, for the mould in its turn must somewhere derive the requisite and inextricable complexity.  We need not go so far back; we should only be in darkness.  Let us keep to the observable facts.

I examine with a magnifying-glass one of the triangular coat-tails of a larva on the point of transformation.  I see a bundle of moderately strong nervures radiating fan-wise.  I see other nervures in the intervals, pale and very fine.  Finally, still more delicate, and running transversely, a number of very short nervures complete the pattern.

Certainly this resembles a rough sketch of the future wing-case; but how different from the mature structure!  The disposition of the radiating nervures, the skeleton of the structure, is not at all the same; the network formed by the cross-nervures gives no idea whatever of the complex final arrangement.  The rudimentary is succeeded by the infinitely complex; the clumsy by the infinitely perfect, and the same is true of the sheath of the wing and the final condition of its contents, the perfect wing.

It is perfectly evident, when we have the preparatory as well as the final condition of the wing before our eyes, that the wing-sheath of the larva is not a simple mould which elaborates the tissue enclosed in its own image and fashions the wing after the complexities of its own cavity.