V2 THE EVOLUTION OF LIFE 
to be used in experiments as to the death-point of 
organisms—we must know for certain that, under 
the conditions employed, the fluid is not a ‘‘ generat- 
ing’ medium. 
To some of the tubes charged with this fluid one 
minim of the fluid A, containing an abundance of 
spores, was added; while others were inoculated 
with a drop of fluid B, containing rods and short 
filaments but no spores. 
The necks of the bulb-tubes, thus charged, were 
then drawn out in the blow-pipe flame, and the 
fluid within each was boiled over the flame for 
about a minute. The neck of the tube was 
hermetically sealed during ebullition, after which 
it was at once plunged in an inverted position into 
a can of boiling water where it was allowed to 
remain exactly ten minutes.! 
The fluids of the two series, similarly heated, 
were then placed side by side in an incubator 
maintained at 122° F..(50°°C.),,and: the resulta 
25 trials (19 containing fluid A, and 6 containing 
fluid B) was that not one of either series fermented, 
although the tubes were kept from ten to fourteen 
days in the incubator. Yet, in control experiments 
with the same urine boiled for ten minutes in 
plugged flasks, and subsequently inoculated with an 
unheated drop of fluid A or of fluid B, fully de- 
veloped fermentation was set up, with the appear- 
ance of swarms of Bacilli, in from sixteen to twenty 
hours : showing clearly that there was nothing in the 
1 The object of inverting the vessel in the can was to bring all parts 
of the tube into contact with the heated fluid contained therein. 

