192 THE EVOLUTION OF LIFE 
that which M. Pasteur formerly made use of), it can 
be easily shown that many properly prepared fluids 
may be made to ferment after they have been ex- 
posed even to 110 C. and upwards. 
This final evidence is, of course, not strictly 
needed for the overthrow of the foundations on 
which M. Pasteur based his germ-theory ; what has 
already been brought forward concerning the fertility 
of boiled acid fluids, and the cause of the fertility 
of boiled neutral fluids, being of itself abundantly 
sufficient for their overthrow. 
This evidence, which I have already given as to 
the cause of the fertility of boiled neutral fluids, also 
goes far to undermine the foundations of the belief 
of other investigators as to the ‘survival of germs”’ 
in any previously boiled fluids. These beliefs all take 
their origin either from Pasteur’s supposed proof of 
such a phenomenon, or from facts of a similar order 
to that by which he was supposed to have demon- 
strated it. The process is essentially this, and it has 
been often repeated : 1st, a deeply rooted conviction 
that living matter cannot arise de novo; 2nd, the 
finding of living matter in fluids which have been 
boiled or further superheated. Such a combination 
of fact and conviction leads to the facile conclusion 
that germs have survived the boiling, quite irrespec- 
tive of the duration of the exposure. And, similarly, 
the above-mentioned conviction continuing to be 
firmly rooted, the finding of living organisms in 
guarded fluids which have been heated to 230° F. 
may be immediately explained in the same way : 
