ON THE CULTURE OF SILK. 83 



cliaiine substance : 5th, a peculiar resinous substance, of which 

 the silk is fonned. 



The saccharine matter nourishes the insect and forms its 

 animal substance. The resinous matter, assimilated in the silk 

 vessels of the worm, forms the silk. Other leaves, besides the 

 mulberry, such as lettuce, dandelion, rose leaves, Stc. possess a 

 similar saccharine matter, and silk worms it is said may be fed 

 on them for two or three weeks with success — but in the last 

 age mulberry leaves are indispensable. Although the worm 

 grows well on other food, the silk vessels are not filled with the 

 pecuhar resin, and no silk can be produced. From this fact, and 

 from the examination of mulberry bark, which contains numerous 

 fibres, closely resembling in strength and appearance silk, we 

 have been led to believe, that the silk substance exists ready 

 formed in the mulberry ; and that the silk worm is only a skilful 

 manufacturer who perhaps adds to it an animal gluten which in 

 some measure modifies its qualities, and spins it into threads. If 

 this be the case, it will be in vain to search longer for a substitute 

 for the mulberry, in any other vegetable, which does not possess 

 similar silk like fibres in its structure. The leaves of the black 

 mulberry are said by some writers to be more nutritious than 

 the white, although worms fed altogether on them will not make 

 so much good silk, as when fed during the last age on the white 

 mulberry. The Chinese mulberry, if we may believe the 

 accounts given of it, is superior to all others for the silk culture. 

 A few of these trees are now cultivated in several nurseries in 

 this country and probably may be rapidly multiplied by grafting 

 or budding. Young, tender, succulent leaves are most suitable 

 for worms in tlieir first ages. In the last, full grown leaves of the 

 oldest trees are to be preferred, as these contain the largest 

 quantity of the silk resin. In the last age no change should 

 be made in tlie kind or quality of the food. The leaves 

 should always, when possible, be picked in fair weather, after 

 the dew has evaporated ; w^et leaves are very injurious to the 

 v/orms. Hence it is necessary to keep on hand sufficient leaves 

 for three or four days, gathered and preserved in a covered 

 glazed or tin vessel, in which they may be kept perfectly sweet 



