196 
THE ART OF REARING 
and then only weigh about two pounds, seven 
ounces. 
When the silk-worms begin to rise, they void a 
quantity of nearly pure water, part of which is 
sometimes discharged through the silk-drawing- 
tubes, and by transpiration. They also evacuate 
a small quantity of solid substance, and then form 
the cocoon in three or four days ; these cocoons 
altogether weigh about one pound and a half. 
Let us now imagine a laboratory similar to that 
which I have hitherto described, calculated to con- 
tain silk-worms proceeding from five ounces of 
eggs, and sufficient to produce about six quintals 
of cocoons ; the following will offer the l-esult : — 
1st. If 360 silk-worms weigh three pounds, three 
ounces and a half, when in their utmost growth 
and perfection, it must clearly appear that the 
whole of the silk-worms of the laboratory, which 
produce GOOpounds weight of cocoons, will weigh 
1285 pounds, three ounces, when they reach then- 
utmost growth. 
And if the 360 silk-worms, previous to begin- 
ning their cocoon, only weigh 42 ounces, it must 
appear equally clear, that the whole of the silk- 
worms of the laboratory will be about 10 quintals, 
50 pounds : and therefore, in three days the silk- 
worms must have lost 2374 pounds weight of 
substance, either solid or liquid, from exhalation, 
or steam. 
