HEAT UPON LIVING MATTER. 145 
would appear within closed vessels previously sub- 
jected to a temperature of 212° F. (owing, as he was 
inclined to think, to a survival of their germs), Spal- 
lanzani was anxious to ascertain whether the differ- 
ence in the capacity of resisting heat, imagined to 
exist in this case between parents and germs, could 
be justified by the establishment of similar differences 
in heat-resisting capacity between other parent organ- 
isms and their germs. 
In carrying out these inquiries, Spallanzani adopted 
the following method: * He placed the eggs, seeds or 
organisms, made use of in his experiments, in a vessel 
containing cold water, into the upper strata of which 
was immersed the bulb of a thermometer. The 
water was then heated slowly, and when the thermo- 
meter indicated that the temperature had been 
attained whose effect it was desired to test, the eggs, 
seeds, or organisms were at once withdrawn and 
placed, under suitable conditions, in a separate 
vessel where their subsequent fate could be watched. 
The effects of different grades of heat upon the ob- 
jects experimented with were thus estimated, and the 
temperature in successive trials was mostly made to 
differ from that last employed by 5°R., or about 
11°F. Operating in this way, and, in the case of eggs 
or seeds, subsequently taking great care to place 
* Loe. cit., p. 53. 
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