THE MODEKN HISTOUY OP SILK. 197 



Mr Swain makes the following judicious remarks 

 on the food of the Silkworm : — " That food," saj's 

 he, " I am confident, will never be found in the 

 leaves of any other tree or plant than those of the 

 mulberry. For although Silkworms will feed on 

 the leaves of lettuces, and will sometimes spin their 

 web, and go through their several metamorphoses 

 without any other food, when they have been accus- 

 tomed to that from their first exclusion from the 

 6gg3, yet they will never thrive so well, become so 

 large, or spin a web, either so good in quality or so 

 abundant in quantity, as when they have been fed 

 during their whole existence in the larva state on 

 their natural food, mulbeny leaves. And supposing 

 the leaves of lettuces to be an equally proper food 

 for them, yet the gi-eat extent of land necessary for 

 the growth of lettuces sufficient for the consumption 

 of any considerable number of worms, must surely 

 render ineffectual every attempt to raise silk upon 

 that plan." 



What necessity can there be for ranging in quest 

 of other nutriment, when the mulberry-tree itself, 

 the acknowledged proper and natural food of these 

 insects, will thrive and prosper in this country as 

 well as most other trees ? In very poor soils, indeed, 

 they grow sparingly. But in soils tolerably rich, 

 either those tliat are naturally so, or enriched by 

 art, they vegetate with all the luxuriance that can 

 be wished. 



