258 
THE ART OF REARING 
and remain in a state of moisture, and covered 
with excrement. 
This condition affects their organs, particularly 
if the litter is hot and damp. The degree of 
alteration in these insects may vary considerably, 
according to the magnitude of the evil causes. 
A large portion of the silk-worms may rot, or 
cease to feed, and die in the course of a few 
days ; others continue to eat a little, but shew 
signs of languor, and dwindle ; others may re- 
cover to a certain degree, and drag on a sickly 
existence, without dying. I have mentioned that 
the first organs injured and deteriorated, even in 
the first ages of the silk-worm, are invariably the 
silk vessels. When deeply attacked, the con- 
stitution of the worm is quite changed, the secre- 
tions are impeded. The insect ceases to be a silk- 
worm, but is a degraded animal, that can no 
longer attain the object for which nature de- 
signed it. 
3. When the air of the laboratory is not 
renewed, and that the damp stagnates in it, two 
great evils ensue. The first is, that the transpi- 
ration is checked ; the second is, that the litter 
ferments, which increases the heat, the damp- 
ness, and corrupts the air, so that the insects 
become weak, and decay. These evils are ag- 
gravated, if the exterior air is mild, still, and 
damp. 
