146 DISEASES OF SILK WORMS. 
of disease in silkworms ; but of these damp seems to 
be the most prejudicial, as will be seen by the fol- 
lowing experiments :—“ If a silkworm,” says Dr 
Lardner, “is introduced into a receiver charged 
with carbonic acid gas, and in which a bird would 
instantly die, although the worm quickly exhibits 
signs of uneasiness and suffering, it will live for ten, 
fifteen, or perhaps twenty minutes. No warm- 
blooded animal could continue alive in such an at- 
mosphere for half that time. If, after remaining a 
few minutes, the worm be withdrawn from the re- 
ceiver, it will not exhibit any sign of injury, but 
will be apparently as healthy as before inhaling 
this pernicious gas. The silkworm appears endued 
with the power to seize upon the minutest portion 
of vital air which may be held by water, as it will 
live for some minutes immersed in this fluid, par- 
ticularly in its first ages ; and, even when seemingly 
dead, it will revive if taken out. It would seem, 
however, that when its power of breathing is ob- 
structed, the worm instantly dies. If, instead of 
plunging it in carbonie acid gas, or in water, its 
eighteen breathing holes are sealed up with grease, 
it expires instantaneously. 
“ Tf a healthy silkworm he confined in a vessel, 
the air in which is charged with moisture, and 
heated to the temperature of 80° to 90°, it will 
very soon exhibit symptoms of indisposition, and 
reject food; the skin will slacken, and the muscles 
