
122 THE EVOLUTION OF LIFE 
explanation than in favour of the other. This it 
was which had to be proved. 
But when positive results were obtained with milk 
or other neutral or slightly alkaline fluids, subjected 
to Schwann’s conditions, the case became altogether 
different. The rule with regard to the inability of 
living things to survive in solutions which had been 
raised to 100° C. for a few minutes was absolute, so 
far as it had gone, and had been founded on the best 
of evidence to which Pasteur as well as others had 
assented. No one therefore should have attempted 
to set it aside, except upon evidence equally direct 
and -equally positive, though more extensive, than 
that upon which the rule had been originally founded. 
Let us now see what was the course adopted by 
M. Pasteur. He explained the discrepancy between 
his earlier and his later experiments by at once 
assuming that the Bacteria and Vibriones which 
were ultimately found in the milk used in these later 
experiments had been derived from “germs” of 
such organisms which (contrary to the general rule 
previously admitted) had been capable of resisting 
the influence of the heat that caused the milk to boil. 
No direct proof of this assumption was ever 
attempted ; yet Pasteur did not hesitate to proclaim 
that the “germs” of such organisms were not 
destroyed by the temperature of 100° C. in neutral 
or slightly alkaline fluids (doc. ce¢., pp. 58-66), and 
that they were destroyed at 110° C., simply because 
in dealing with such fluids, organisms were found 
after they had been heated to the one temperature, 
