SILK-WORMS. 
275 
I can testify from my own experience that there 
is a more sudden and dangerous effect to be feared 
from stagnant, damp, and hot air, than from air 
stagnant but dry, and at a regulated degree of 
temperature # . 
* The experiments I made, proved to me, that silk-worms 
being - animals without red or hot blood, vitiated mephitic air 
is not so instantly and eminently fatal to them as very damp 
hot air. 
If a silk-worm is introduced into a bottle filled with mephi- 
tic air, in which some of the insects litter had been put, and 
in which a candle would go out, and a bird die, the worm will 
live 10, 15, or 20 minutes, although at the end of a few mi- 
nutes it will appear to suffer, but no warm-blooded animal 
could stand it half the time. If in the course of a few minutes 
the animal is withdrawn from the mephitic air, it does not ap- 
pear at all the worse for it, but seems healthy ; therefore it must 
have extracted some vital air from the mephitic air to have 
breathed at all. 
The silk- worm can also inhale the slightest particles of vital 
air which water may contain, and can live some minutes im- 
mersed in it, particularly when small, and although it may ap- 
pear dead, it will revive when taken out of the water. 
If, however, it cannot find any particle of vital air, it directly 
dies ; for if instead of plunging the worm in mephitic air, or 
in water, you stop up the eighteen breathing tubes or vessels 
with grease, the animal will expire instantly. 
If a healthy silk-worm is put into a vessel full of vital air, 
but charged with moisture, and at a temperature of 8S° or 98°, 
it will shortly become flabby, will cease to eat, and perish very 
soon afterwards. 
The warm-blooded animal, on the contrary, such as a bird, 
will live very well at SS° and 9S° of temperature, whatever be 
the moisture, so it has plenty of vital air. 
This proves how different is the organization of these two 
classes of animals. The functions of life are favourably per- 
N 6 
