SILK-WORMS. 
243 
The whitest cocoons should be carefully se- 
lected for the production of eggs, that the seed 
may not degenerate. 
The art of raising cocoons, being generally to- 
tally separate from the trade of spinning the silk, 
and in different hands, there exists no union be- 
tween these two classes, which is greatly injurious 
to both, and retards general improvement : this is 
the reason so few persons will take the trouble 
of raising the silk-worms of three casts, or the 
white cocoons, although the quality of either is 
superior to that of the ordinary silk. 
The white cocoons, far from obtaining a better 
price, are rather rejected, under an idea that the 
worms they produce are more delicate than the 
others, which is entirely an error. 
The silk-worms that spin white silk deserve the 
observation and attention of the cultivator. If 
I reared silk-worms for the purpose of myself 
spinning the silk, I would cultivate only the silk- 
worm of three casts, and the silk-worms that 
spin white silk as preferable to all others, and 
every year would choose the very whitest and 
finest cocoons for seed, to prevent the degenera- 
tion of the species. 
4. The common Silk-Worm of Four Casts. 
This species is the most generally cultivated, and 
that of which we principally treat in this book. 
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