318 
THE ART OF REARING 
If all these eggs produced a worm, and that all 
the worms lived, from one ounce of eggs, about 
3731bs. of cocoons would be obtained, because 
150 cocoons weigh about one pound and a half. 
To form an ounce of eggs of common-sized 
worms of four casts or moultings, 39,168 will be 
required ; if all these eggs produced a worm each, 
and all these worms lived, this ounce of eggs 
would yield 1621bs. of cocoons, because about 
360 cocoons weigh a pound and a half. 
To form an ounce of eggs of silk-worms of three 
castings or moultings, it will require 42,200 eggs. 
If all these eggs produced a worm each, and 
all these worms lived, the ounce of eggs would 
yield 1051bs. of cocoons, because 600 cocoons 
weigh about a pound and a half. 
From these positive facts, it may easily be as- 
certained, by the quantity of cocoons obtained, 
how many eggs have failed, and how many have 
died in the various ages ; it will afterwards be 
of use in determining which method of rearing 
the worms is most favourable to their preserva- 
tion. 
From the time of laying the eggs, until they 
are taken off the cloths, that is, a period of nine 
months, they only lose about of this weight. 
From the day the eggs of the common silk- 
worms of four casts are put into the stove-room, 
until the time they begin to hatch, they lose, on an 
