mineral matter. The solution becomes muddy if
oxalate of ammonia be added and 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 separate 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,[11] 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.

[Footnote 11: Three species of Digger-wasps.--_Translator's Note_.]

When the exit-way is prepared and the cell upholstered in velvet and
closed with a three-fold 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 worm,
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
not be able to turn from end to end; he will not even be capable of
bending, if some sudden wind should make the passage difficult. He
must absolutely find the door in front of him, lest he perish in the
casket. Should the grub forget this little formality, should it lie
down to its nymph