260 THE EVOLUTION OF LIFE 
unless heated to 100 C. or over for a few 
minutes.” 
It must be borne in mind that in the experiments 
last recorded we were dealing with sterilised tubes 
containing distilled water, and two or three chemical 
ingredients practically free from micro-organisms, 
yet after the sealed tubes had been exposed to the 
temperature of 100 C. for ten minutes, and had 
subsequently been kept for a few weeks exposed 
either to diffuse daylight or to the heat of an 
incubator, they have been found, on examination, to 
contain multitudes of micro-organisms. The micro- 
organisms, too, have been, in part, of such a kind 
(Torula and Cocci) as are well known to be killed 
at temperatures ranging from 60-75 C., and although 
some Bacilli also have been present (known to be 
destroyed at similar temperatures), there is no reason 
whatever for supposing that the distilled water or either 
of the three chemicals employed would have contained 
the more resistant spores of Bacilli. These are, 
moreover, as I have shown, resistant only after a 
previous desiccation, and to a much more limited 
extent than is generally supposed. 
No loophole for doubt must, however, be left. 
Although I have used freshly distilled water, in 
which no one has yet found spores of Bacilli, let us 
deal with our problem as though this distilled water 
might contain such organisms and their spores as 
are to be met with in ordinary tap-waters, or even 
in hay infusions. We have seen that after prolonged 
researches on this subject the present sub-director of 
