178 THE EVOLUTION OF LIFE 
) 
of error had been ‘‘completely eliminated by me,’ 
but not the third, since I had not been accustomed 
to flambé the vessels employed. 
Now it is perfectly certain that this is a con- 
dition never mentioned and never adopted by 
Pasteur himself in his previous experiments, as 
described in 1862. In the long interval that 
elapsed between his reply to me on August 7, and 
the resumption of the discussion in the following 
January, he had, during part of this time, been 
engaged in an investigation of the relative purity 
of different waters, in conjunction with M. Joubert ; 
an investigation which, as he says in a report of 
its results in the Comptes Rendus for January 29, 
was undertaken in consequence of the discussion 
with me. In a note to this communication, he 
refers to investigations on the same subject made by 
Burdon Sanderson in 1871, who also found Bacteria 
widely distributed in ordinary tap waters in London, 
but disagreed with Pasteur as to the frequency 
of germs of Bacteria in the air—notwithstanding all 
that Pasteur had said in his memoir of 1862. 
Sanderson, therefore, inclined to the conclusion 
that the Bacteria which appear in experiments re- 
lative to spontaneous generation come, as Pasteur 
puts it, “Exclusivement de l’eau ayant servi au 
nettoyage des vases, quand on na les flambe pas.” 
Although Pasteur professed not to like these con- 
clusions of Sanderson, the latter point seems to 
have made a deep impression upon him, so that 
he soon took a totally different view concerning 
my experiments, He gave up the interpretation 
