of the gum which the insect uses in forming it. Warm water, which is found sufficient in the case of the common silk-worm, has in most instances no perceptible effect on it; nor, in fact, any solvent that has yet been tried. The silk, therefore, can be made available only in an imperfect way, by tearing it from the cocoon and carding it like wool. The subject is well worthy the attention of chemists, for the discovery of a substance which should dissolve the gum without destroying the texture of the thread, would enable us to add incalculably to the sources whence the finest silk may be derived. Perhaps a hint might be taken on this point from the fact that the insect itself is provided with a fluid which dissolves the gum, and which it employs for the purpose of opening a passage for itself when emerging from the cocoon. Could a portion of this substance be obtained and subjected to analysis, the ingredient to which it owes its solvent quality might be detected. In some cases it is discharged in great abundance.
