

THERMAL DEATH-POINTS 47 
experiments in a vessel containing cold water, within 
the upper strata of which was immersed the bulb of 
a thermometer. The water was then heated slowly, 
and when the thermometer indicated that the 
temperature had been attained whose effects it was 
desired to test, the eggs, seeds, or organisms were 
at once withdrawn and placed, under suitable con- 
ditions, in a separate vessel where their subsequent 
fate could be watched. The effects of different 
grades of heat upon the objects experimented 
with were thus estimated, and the temperature 
in successive trials was mostly made to differ 
from that last employed by 5° R.—that is, about 
i el 
We need only refer to a few of the results 
obtained by Spallanzani. Silk-worms’ eggs and 
the eggs of the Elm-moth developed less and less 
frequently when successive batches were heated 
to temperatures approaching 144$° F. When they 
were actually submitted to this heat all perished, 
though the highest temperature followed by develop- 
ment is not recorded. Silk-worms themselves, as 
well as the caterpillars of the Elm-moth, were 
uniformly killed as soon as the water in which they 
were immersed attained 108$° F. Eggs of the 
common Blow-fly also only developed in very small 
numbers when raised to the temperature of 135°; 
all perished at 140°; and larve reared from the 
eggs perished, as those of the Silk-worm and Elm- 
moth had done, as soon as the temperature of the 
water rose to 1084°. Certain aquatic organisms, 
such as Leeches, Nematode and other Worms, 
