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.