means of
replenishing it. My suspicions are well founded. For three days the
prisoner struggles desperately, but cannot ascend by so much as an inch.
It is impossible to fix the material removed in the absence of
moisture; as soon as it is thrust aside it slips back again. The labour
has no visible result; it is a labour of Sisyphus, always to be
commenced anew. On the fourth day the creature succumbs.

With the intestines full the result is very different.

I make the same experiment with an insect which is only beginning its
work of liberation. It is swollen with fluid, which oozes from it and
moistens the whole body. Its task is easy; the overlying earth offers
little resistance. A small quantity of liquid from the intestines
converts it into mud; forms a sticky paste which can be thrust aside
with the assurance that it will remain where it is placed. The shaft is
gradually opened; very unevenly, to be sure, and it is almost choked up
behind the insect as it climbs upwards. It seems as though the creature
recognises the impossibility of renewing its store of liquid, and so
economises the little it possesses, using only just so much as is
necessary in order to escape as quickly as possible from surroundings
which are strange to its inherited instincts. This parsimony is so well
judged that the insect gains the surface at the end of twelve days.

The gate of issue is opened and left gaping, like a hole made with an
augur. For some little time the larva wanders about the neighbourhood of
its burrow, seeking an eyrie on some low-growing bush or tuft of thyme,
on a stem of grass or grain, or the twig of a shrub. Once found, it
climbs and firmly clasps its support, the head upwards, while the talons
of the fore feet close with an unyielding grip. The other claws, if the
direction of the twig is convenient, assist in supporting it; otherwise
the claws of the two fore legs will suffice. There follows a moment of
repose, while the supporting limbs stiffen in an unbreakable hold. Then
the thorax splits along the back, and through the fissure the insect
slowly emerges. The whole process lasts perhaps half an hour.

There is the adult insect, freed of its mask, and how different from
what it was but how! The wings are heavy, moist, transparent, with
nervures of a tender green. The thorax is barely clouded with brown. All
the rest of the body is a pale green, whitish in places. Heat and a
prolonged air-bath are necessary to h