168 
THE ART OF REARING 
attained their greatest development and heaviest 
weight, I have observed the following facts : — 
1st. That in their growth they are become 
forty times larger than they were when first 
hatched, being then about the size of one line. 
2d. That, in thirty days, their weight is become 
nine thousand times greater, since it required 
54,525 young hatched silk-worms to form an 
ounce (Chap. V. § 3.), whereas six silk-worms, 
when full grown, are now sufficient to weigh an 
ounce. 
3d. That the fifth age alone, which is their 
longest and most happy period, comprises two- 
thirds of their lives. 
From the ninth day of the fifth age, and the 
thirty-first of the life of the silk-worm, until the 
completion of its maturity, we shall see, that al- 
though they need little food, they still require 
great care. Of which we shall speak in the fol- 
lowing Chapter. 
Reckoning the 240 pounds of sorted leaves, 
which are to be given on the morrow (or tenth 
day), the worms proceeding from five ounces of 
eggs will have consumed, in the fifth age, 
5490 pounds of sorted and picked leaves. 
Adding to this 510 pounds of refuse and pick- 
ings of the leaves, the total weight taken from the 
tree will be 6000 pounds of leaves. 
The total weight of dung drawn from the wicker 
trays in the fifth age is about 3300 pounds weight, 
