94 
THE ART OF REARING 
pounds of picked leaves, chopped small ; in add- 
ing four pounds and a half, the refuse picked off the 
leaves, the weight will make 34i pounds of mul- 
berry leaves, or about seven pounds of leaves 
from the tree to each ounce of silk-worms. 
To complete the exactness of these observations, 
we must add two other alterations, to which the 
silk-worms are subject before their moulting. 
1st. We have seen (Chap. Y. §4.) that, to form 
an ounce of silk-worms just hatched, it requires 
54,620 worms ; after the first moulting, 3840 are 
sufficient to make up that weight. Thus the silk- 
worm has increased, in about six days, fourteen 
times its own weight. 
2d. Before the above six days, the silk-worm was 
about a line in length, and after those days it is 
about four lines long. 
In the first age the air of the laboratory should 
only be renewed by opening the doors. The ne- 
cessary degree of temperature must be maintained 
by the stove, and wood-fires in the fire-places, as 
we shall shew hereafter. 
Nothing further is necessary for the thriving of 
the worms, and their healthy continuance. 
2. Rearing of the Silk-worm in the Second Age. 
Nearly seventy-three feet four inches square of 
table or wicker-trays are needed for the accommo- 
dation of the worms proceeding from five ounce^ 
