SILK, -WORMS. 
261 
4. Diseases which ill Management will also occa- 
sion, in the fifth Age of the Silk-worm. 
In the fifth age, the silk-worms are most subject 
to very serious disorders, perfectly unknown in 
the preceding ages. The insects being then far 
advanced and large, the cultivator must more 
especially regret to see them perish, as the 
losses are heavier. We shall soon shew that in 
these cases also we must attribute the evils to 
ill management, so generally practised. 
To demonstrate this truth, I am obliged to 
enter into particulars upon some subjects that 
may appear beyond the comprehension of the 
mere practical cultivators. I will, however, 
strive to explain myself with such clearness, as 
may instruct and convince them. Should I fail 
in making myself understood, in treating of the 
origin of these diseases, it will at least be suf- 
ficient, that I should be comprehended when I 
describe the practical means I shall point out 
as necessary to prevent disease occurring. 
The silk-worm devours, in proportion to the 
weight it acquires, an enormous quantity of raw 
vegetable substance, compared to that consumed 
by any other domestic animal. (Chap. XIY.) 
Every animal that feeds upon fresh vegetable 
substances, necessarily receives a large portion of 
water into its body, as well as alkaline, acid, 
