ly shaped as itself. Each
spur is enclosed in a similar spur; each tooth engages in the hollow of
a similar tooth, and the sheath is so closely moulded upon the shank
that a no more intimate contact could be obtained by replacing the
envelope by a layer of varnish applied with a brush.

Nevertheless the tibia, long and narrow as it is, issues from its sheath
without catching or sticking anywhere. If I had not repeatedly seen the
operation I could not believe it possible; for the discarded sheath is
absolutely intact from end to end. Neither the terminal spurs nor the
double rows of spines do the slightest damage to the delicate mould. The
long-toothed saw leaves the delicate sheath unbroken, although a puff of
the breath is enough to tear it; the ferocious spurs slip out of it
without leaving so much as a scratch.

I was far from expecting such a result. Having the spiny weapons of the
legs in mind, I imagined that those limbs would moult in scales and
patches, or that the sheathing would rub off like a dead scarf-skin. How
completely the reality surpassed my anticipations!

From the spurs and spines of the sheath, which is as thin as the finest
gold-beaters' skin, the spurs and spines of the leg, which make it a
most formidable weapon, capable of cutting a piece of soft wood, emerge
without the slightest display of violence, without a hitch of any kind;
and the empty skin remains in place. Still clinging by its claws to the
top of the wire cover, it is untorn, unwrinkled, uncreased. Even the
magnifying-glass fails to show a trace of rough usage. Such as the skin
was before the cricket left it, so it is now. The legging of dead skin
remains in its smallest details the exact replica of the living limb.

If any one asked you to extract a saw from a scabbard exactly moulded
upon the steel, and to conduct the operation without the slightest
degree of tearing or scratching, you would laugh at the flagrant
impossibility of the task. But life makes light of such absurdities; it
has its methods of performing the impossible when such methods are
required. The leg of the locust affords us such an instance.

Hard as it is when once free of its sheath, the serrated tibia would
absolutely refuse to leave the latter, so closely does it fit, unless it
were torn to pieces. Yet the difficulty must be evaded, for it is
indispensable that the sheaths of the legs should remain intact, in
order to afford a firm support until the insect