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.