148 ANIMALS KILLED IV, 
From a fewer in a fouth expofure, I took wheel 
animals’ fand, which had been expofed. to the 
heat of the fun twenty-nine days in the middle 
of fummer. The thermometer ftood at 129°, 
133°, 138°, in the funthine; but the animals 
were not injured, for I had a great number very 
vivacious when the fand was wet. ) 
A little of this fand was expofed the whole rat 
mer, in very thin glafs tubes, on the outfide of a » 
fouth window, where the reflection of a neighbour- 
ing wall excited extreme heat, During fome of the 
hotteft days, the thermometer rofe to 142° 3 but 
this did not injure the wheel animals. On wet- 
ting the fand, they appeared with the fame live- 
linefs and vigour, and in the fame abundance, as 
in other fand from the fame place expofed in a 
north window, and feldom or never experiencing 
the folar rays. Therefore it is evident, that the 
exceffive heat of fummer is not fo prejudicial to 
wheel animals as to deftroy the refurgent faculty, 
But is it the fame when revived? Is this degree 
of heat equally fupportable? I have alfo expofed 
the tubes with fand and water, containing a great 
number of living wheel animals, in the fame 
warm fituation. ‘The confequence was very dif. 
ferent. In half an hour, the heat of the fun at 
135° killed them. Thus, it is otherwife with 
wheel animals, dry and deprived of life, and 
svhen they are animated and in motion. I after. 
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