BOMBYCIDJE. 131 



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 che- 

 mists, 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. 



