412. ANIMALS AND VEGETABLES ITIL 
leterious quality of the exhalations is fo terrible 
to all fpecies of animals, that its effects are ex- 
tended to thofe that never felt the lively impref- 
fions of the air, from their conftant abede at the 
bottom of waters. The fnails and little fnakes of 
{tagnant waters fhewed me this. ‘They crawled 
over the bottom of an open veflel of water, with- 
out betraying any fign of uneafinefs: but, when 
confined in a very fmall veffel, they became reft- 
tefs, afcended the fides of the veffel, and, con- 
trary to their ufual habits, left the water, and 
foon expired. ‘Thus the influence of the exha- 
lations aéts under waters, which is indubitable 
from the foetor communicated to thofe in receiv- 
ers, as well as to what furrounds them whenever 
it is copious. 
But how do thefe peftilential exhalations occa- 
fion the death of animals, if they do not kill by 
depriving them of refpiration? It is not by co- 
agulating, diffolving, or decompofing the fluids. 
The blood preferves its original fluidity immedi- 
ately after the death of animals in this way, and 
flows in the ferum; and its globules retain their 
fize and figure. Befides, if the exhalations co- 
agulated the blood, or contributed to render it 
more fluid, they could not occafion fudden death ; 
for animals deprived of blood die where they 
abound (1). ‘ 
I have 
(1) De Fenomeni della Circolazione. 
