ivalent, he remains on the
look-out, waiting, if necessary, for whole days at a time. At last the
need of air and food obliges the besieged non-combatant to show
himself: at least, the door is set slightly ajar. That is enough. The
Drilus is on the spot and strikes his blow. The door can no longer be
closed; and the assailant is henceforth master of the fortress. Our
first impression is that the muscle moving the lid has been cut with a
quick-acting pair of shears. This idea must be dismissed. The Drilus is
not well enough equipped with jaws to gnaw through a fleshy mass so
promptly. The operation has to succeed at once, at the first touch: if
not, the animal attacked would retreat, still in full vigour, and the
siege must be recommenced, as arduous as ever, exposing the insect to
fasts indefinitely prolonged. Although I have never come across the
Drilus, who is a stranger to my district, I conjecture a method of
attack very similar to that of the Glow-worm. Like our own Snail-eater,
the Algerian insect does not cut its victim into small pieces: it
renders it inert, chloroforms it by means of a few tweaks which are
easily distributed, if the lid but half-opens for a second. That will
do. The besieger thereupon enters and, in perfect quiet, consumes a
prey incapable of the least muscular effort. That is how I see things
by the unaided light of logic.

Let us now return to the Glow-worm. When the Snail is on the ground,
creeping, or even shrunk into his shell, the attack never presents any
difficulty. The shell possesses no lid and leaves the hermit's
fore-part to a great extent exposed. Here, on the edges of the mantle,
contracted by the fear of danger, the Mollusc is vulnerable and
incapable of defence. But it also frequently happens that the Snail
occupies a raised position, clinging to the tip of a grass-stalk or
perhaps to the smooth surface of a stone. This support serves him as a
temporary lid; it wards off the aggression of any churl who might try
to molest the inhabitant of the cabin, always on the express condition
that no slit show itself anywhere on the protecting circumference. If,
on the other hand, in the frequent case when the shell does not fit its
support quite closely, some point, however tiny, be left uncovered,
this is enough for the subtle tools of the Lampyris, who just nibbles
at the Mollusc and at once plunges him into that profound immobility
which favours the tranquil proceedings of the consumer