SILK-WORMS. 
333 
worm, at its highest degree of size and growth, 
should, on an average, be only three inches long, 
and nine lines in circumference, the skin must be 
2| inches, square surface ; the 12,860 skins must 
therefore offer a surface of 28,935 square inches. 
This surface is equal to 1 10 feet, and does not 
weigh above 4 i ounces. Knowing so exactly the 
various proportions of the cocoons containing the 
healthy chrysalis, w r e shall see how different are 
those of the calcined or decayed chrysalis. 
These proportions should be known, because 
they are immediately connected with the art of 
rearing silk-worms with the utmost advantage to 
the proprietors. 
The ideas entertained on the subject of the co- 
coon containing a calcined •worm, are generally 
confused. 
Many cultivators complain of the loss they sus- 
tain in selling the light cocoons to the silk-spinners 
at a low price ; and the purchasers deny deriving 
any considerable advantage from this purchase. 
The purchaser may not always be wrong, but 
still the losses of those w r ho sell are heavy and real ; 
and it is difficult to understand how they could for 
years have been satisfied with complaining, instead 
of seeking to discover and overcome the cause of 
these losses. (Chap. XII.) 
