1s0 ANIMALS KILLED IV. 
‘themfelves, compreffed’and indurated. Befides, 
in this ftate, their globular’ figure prefents lefs 
furface to the action of the fire. The heat acts 
alone on dry wheel animals; when alive, it acts 
in conjunction with the water, which ‘powerfully 
concurs in lacerating them and deftroying: their 
organization, from its particles being fubtilized 
by the heat and rendered more active and pene- 
trating. Thus itis that dry wheel animals can 
vefift the heat of warm water lefs than that of 
the fire itfelf. 
Having fecn the effet of heat on wheel ani - 
mals, it was-neceflary to fee the effect of cold. 
With this intent, I took the fand of fewers 
and from the hollows of the eaves and tiles, 
where they are found during the moft intenfe 
cold of winter, when roofs: are covered with 
{now and ice. The fand, moiftened with water, 
became fo firm and connected by the cold that it 
was as hard as: aftone; but the wheel animals 
were not injured. After melting this mixture of 
sce and fand, a great many revived; however, 
their refurrestion appeared lefs immediate. 
The greateft cold of winter was 16°. I there- 
fore determined to expofe the wheelers found on 
roofs to a degree more intenfe : and taking fome 
portions of frozen fand from the bottom of a 
fewer, I put them in a glafs veffel which was 
placed three hours in cold 11° below o, obtain-- 
ed. 
