SILK-WORMS. 
219 
If for a thousand years a laboratory produced 
good cocoons, the eggs of those cocoons, being 
carefully preserved, will for a thousand years 
continue good and undegenerate, like the eggs of 
any other oviparous domestic animal that we are 
acquainted with. 
To suppose that the good cocoons of a cultiva- 
tor, after a few years, are no longer fit to produce 
good seed, and yet that those cocoons can give 
good seed for the use of any other laboratory, 
would be to admit a superstitious contradiction 
which reason, practice, and science alike con- 
demn. 
We shall comprise in three paragraphs all that 
treats on the production and preservation of the 
eggs : 
1st. Birth and coupling of the moth. 
2nd. Separation of the moth, and deposition of 
the impregnated eggs. 
3rd. Preservation of the eggs. 
1 . Hatching of the Moths, and their Propagation. 
If the cocoons that have been selected to produce 
eggs are kept in a temperature of 66°, the moths 
begin to be hatched after fifteen days ; if the co- 
coons are kept in a heat between 71° and 73°, 
they begin to come forth after eleven or twelve 
days. 
In the first case, all the moths occupy about 
