SILK-WORMS. 
325 
the last period or age, every part of the laboratory 
should be opened ; but often In avoiding one dan- 
ger, they meet another, such as exposing the worms 
to cold and wind, which may harden them, and 
cause them to drop off at the moment they had 
begun to weave the cocoon. 
There is only the gentle and continual renewal 
and motion of the internal air that can be benefi- 
cial and natural to the silk-worm. 
It is considered astonishing, that one single worm 
which, when first hatched, only weighs the hun- 
dredth part of a grain, should consume, in about 
thirty days, above an ounce of leaves, that is to 
say, that it devours, in vegetable substance, about 
b0,000 times its primitive weight. 
The result of my experiments tends to shew, 
that in warmer climates than ours, the silk-worms 
consume rather less leaf than I have here stated, 
because the quality of the leaf is more nutritive. 
In the favourable regions of Dalmatia, I obtain- 
ed in 1807 one pound and a half of cocoons from 
fifteen pounds of leaves, and fifteen pounds of co- 
coons yielded one pound and a half of silk, although 
it was not so delicate and fine as ours. Not- 
withstanding the richness of the produce in that 
province, on which nature has lavished so much, 
there are few mulberry plantations to be found 
in it. 
