ster goes in, never to show itself again. But there is one precaution
to be taken first. With its front tarsi, the insect carefully brushes
the bump about to disappear from view, lest grit should lodge in the
cranium when the two halves of the head are joined for good.

The maggot is aware of the trials that await it when, as a fly, it will
have to come up from under ground; it knows beforehand how difficult the
ascent will be with the feeble instrument at its disposal, so difficult,
in fact, as to become fatal should the journey be at all prolonged.
It foresees the dangers ahead of it and averts them as well as it can.
Gifted with two iron shod sticks in its throat, it can easily descend to
such depths as it pleases. The need for greater quiet and a less trying
temperature calls for the deepest possible home: the lower down it is,
the better for the welfare of the worm and the pupa, on condition that
descent be practicable. It is, perfectly; and yet, though free to obey
its inspiration, the grub refrains. I rear it in a deep pan, full of
fine, dry sand, easy to excavate. The interment never goes very far.
About a hand's breadth is all that the most progressive digger ventures
upon. Most of the interred remain nearer still to the surface. Here,
under a thin layer of sand, the grub's skin hardens and becomes a
coffin, a casket, wherein the transformation sleep is slept. A few
weeks later, the buried one awakes, transfigured but weak, having
naught wherewith to unearth herself but the throbbing hernia of her open
forehead.

What the maggot denies itself it is open to me to realize, should I
care to know the depth whence the fly is able to mount. I place fifteen
bluebottle pupae, obtained in winter, at the bottom of a wide tube
closed at one end. Above the pupae is a perpendicular column of fine,
dry sand, the height of which varies in different tubes. April comes and
the hatching begins.

A tube with six centimeters of sand, the shallowest of the columns under
experiment, yields the best result. Of the fifteen subjects interred
in the pupa stage, fourteen easily reach the surface when they become
flies. Only one of them perishes, one who has not even attempted the
ascent. With twelve centimeters of sand, four emerge. With twenty
centimeters, two, no more. The other flies, jaded with their exertions,
have died at a higher or lower stage of the road. Lastly, with yet
another tube wherein the column of sand measured sixty