SILK-WORMS. 
21 
every care was not taken which its develope- 
ment, its growth, and its perfection require : evi- 
dently proving that this insect is a native of 
much warmer climates than ours. 
And such, in fact, is the climate of the southern 
part of the Chinese Empire, whence originated 
the silk-worm, and where written documents are 
preserved, tending to prove that these insects 
were raised there, 2700 years before 'the Chris- 
tian sera. 
The silk-worms passed insensibly into Persia, 
into India, and into various parts of Asia; they 
were then conveyed to the Isle of Cos ; and in the 
sixth century they were introduced into Con- 
stantinople, where the emperor Justinian made 
them an object of public utility. They were 
successively cultivated in Greece, in Arabia, in 
Spain, in Italy, in France, and in all places 
where any hope could be indulged of their suc- 
ceeding. 
The silk-worm, being thus subjected to domes- 
tic care and habits, must, necessarily, like every 
other domesticated animal, have undergone par- 
ticular modifications, which have produced new 
breeds or varieties, more or less different. 
It is thus we may account for some silk-worms 
moulting or casting their skins four times, others 
only three times ; thus some form large cocoons, 
nearly thrice the weight of the common cocoon. 
