nitric
acid, discharging little gaseous bubbles. The process of solution is a
slow one, requiring several hours for a tiny fragment. Everything is
dissolved, except a few yellowish flocks, which appear to be of an
organic nature. As a matter of fact, a piece of the hatch, when
subjected to heat, blackens, proving the presence of an organic glue
cementing the mineral matter. The solution becomes muddy if oxalate of
ammonia be added; it then deposits a copious white precipitate. These
signs indicate calcium carbonate. I look for urate of ammonia, that
constantly recurring product of the various stages of the
metamorphoses. It is not there: I find not the least trace of murexide.
The lid, therefore, is composed solely of carbonate of lime and of an
organic cement, no doubt of an albuminous character, which gives
consistency to the chalky paste.

Had circumstances served me better, I should have tried to discover in
which of the worm's organs the stony deposit dwells. I am however,
convinced: it is the stomach, the chylific ventricle, that supplies the
chalk. It keeps it separated from the food, either as original matter
or as a derivative of the ammonium urate; it purges it of all foreign
bodies, when the larval period comes to an end, and holds it in reserve
until the time comes to disgorge it. This freestone factory causes me
no astonishment: when the manufacturer undergoes his change, it serves
for various chemical works. Certain Oil-beetles, such as the Sitaris,
locate in it the urate of ammonia, the refuse of the transformed
organism; the Sphex, the Pelopaei, the Scoliae use it to manufacture
the shellac wherewith the silk of the cocoon is varnished. Further
investigations will only swell the aggregate of the products of this
obliging organ.

When the exit-way is prepared and the cell upholstered in velvet and
closed with a threefold barricade, the industrious worm has concluded
its task. It lays aside its tools, sheds its skin and becomes a nymph,
a pupa, weakness personified, in swaddling-clothes, on a soft couch.
The head is always turned towards the door. This is a trifling detail
in appearance; but it is everything in reality. To lie this way or that
in the long cell is a matter of great indifference to the grub, which
is very supple, turning easily in its narrow lodging and adopting
whatever position it pleases. The coming Capricorn will not enjoy the
same privileges. Stiffly girt in his horn cuirass, he will