light up
its neighbours by reflexion and give us a clear view of each individual
specimen. But not at all: the luminous party is a chaos in which our
eyes are unable to distinguish any definite form at a medium distance.
The collective lights confuse the light-bearers into one vague whole.

Photography gives us a striking proof of this. I have a score of
females, all at the height of their splendour, in a wire-gauze cage in
the open air. A tuft of thyme forms a grove in the centre of their
establishment. When night comes, my captives clamber to this pinnacle
and strive to show off their luminous charms to the best advantage at
every point of the horizon, thus forming along the twigs marvellous
clusters from which I expected magnificent effects on the
photographer's plates and paper. My hopes were disappointed. All that I
obtain is white, shapeless patches, denser here and less dense there
according to the numbers forming the group. There is no picture of the
Glow-worms themselves; not a trace either of the tuft of thyme. For
want of satisfactory light, the glorious firework is represented by a
blurred splash of white on a black ground.

The beacons of the female Glow-worms are evidently nuptial signals,
invitations to the pairing; but observe that they are lighted on the
lower surface of the abdomen and face the ground, whereas the summoned
males, whose flights are sudden and uncertain, travel overhead, in the
air, sometimes a great way up. In its normal position, therefore, the
glittering lure is concealed from the eyes of those concerned; it is
covered by the thick bulk of the bride. The lantern ought really to
gleam on the back and not under the belly; otherwise the light is
hidden under a bushel.

The anomaly is corrected in a very ingenious fashion, for every female
has her little wiles of coquetry. At nightfall, every evening, my caged
captives make for the tuft of thyme with which I have thoughtfully
furnished the prison and climb to the top of the upper branches, those
most in sight. Here, instead of keeping quiet, as they did at the foot
of the bush just now, they indulge in violent exercises, twist the tip
of their very flexible abdomen, turn it to one side, turn it to the
other, jerk it in every direction. In this way, the searchlight cannot
fail to gleam, at one moment or another, before the eyes of every male
who goes a-wooing in the neighbourhood, whether on the ground or in the
air.

It is very like