the eggs are arranged in a row, not end to end, but partially
overlapping. The larva escaping from the hinder ranks has to squeeze
past the empty shells, still in position, of the eggs which have already
hatched, so that the narrowness of the passage is increased by the empty
egg-shells. Under these conditions the larva as it will be presently,
when it has torn its temporary wrappings, would be unable to effect the
difficult passage. With the encumbrance of antennæ, with long limbs
spreading far out from the axis of the body, with curved, pointed talons
which hook themselves into their medium of support, everything would
militate against a prompt liberation. The eggs in one chamber hatch
almost simultaneously. It is therefore essential that the first-born
larvæ should hurry out of their shelter as quickly as possible, leaving
the passage free for those behind them. Hence the boat-like shape, the
smooth hairless body without projections, which easily squeezes its way
past obstructions. The primary larva, with its various appendages
closely wrapped against its body by a common sheath, with its fish-like
form and its single and only partially movable limb, is perfectly
adapted to make the difficult passage to the outer air.

This phase is of short duration. Here, for instance, a migrating larva
shows its head, with its big black eyes, and raises the broken fibres of
the entrance. It gradually works itself forward, but so slowly that the
magnifying-glass scarcely reveals its progress. At the end of half an
hour at the shortest we see the entire body of the creature; but the
orifice by which it is escaping still holds it by the hinder end of the
body.

Then, without further delay, the coat which it wears for this rough
piece of work begins to split, and the larva skins itself, coming out of
its wrappings head first. It is then the normal larva; the only form