fil. CONFINED IN STAGNANT arr. 89 
cident, without knowifg in what that accident 
confifted, which rendered his refults different 
from thofe of others. It might be occafioned by 
the birds themfelves ; perhaps that which he cons 
fined alone was lefs vigorous than thofe he con- 
fined together ; whence all died in the fame time. 
Perhaps in his experiment with the two birds, 
all communication with the external air had not 
been prevented, which might eafily happen if the 
top of the veffel was covered only with leather, 
or any fubftance of a fimilar nature ; or if, on 
inverting the mouth of the veffel, it had not been 
well fixed to the plane of pofition with mattic, 
glue, or the like. It is very poffible that fome 
invifible hole might remain, or fome opening, by 
which the air might get admiffion. To obviate 
all fufpicion of foreign air, it is neceflary to feal 
the veffel hermetically, or immerfe the mouth 
deep in water, as will be more clearly explained. 
In the preceding chapter, we have feen how much 
the heat of the weather accelerates the death of 
the animals confined. May we not fufpeé&t that 
Piftorini made the experiment on a fingle bird in 
very warm weather, and on two in very cold: 
and that the death of the two birds was by this 
means retarded by the cold of the atmofphere, 
which would protraé& life as long as the fingle 
bird furvived ? | : 
‘ Let 
