PASTEUR, KOCH, AND OTHERS 287 
He planned and executed one experiment which he sup- 
posed was conclusive. In introducing it he said: “The 
opponents of spontaneous generation assert that the germs of 
microscopic organisms exist in the air, which transports them 
to a distance. What, then, will these opponents say if I 
succeed in introducing the generation of living organisms, 
while substituting artificial air for that of the atmosphere?” 
He filled a flask with boiling water and sealed it with great 
care. This he inverted over a bath of mercury, thrusting 
the neck of the bottle into the mercury. When the water 
was cooled, he opened the neck of the bottle, still under the 
mercury, and connected it with a chemical retort containing 
the constituents for the liberation of oxygen. By heating 
the retort, oxygen was driven off from the chemical salts 
contained in it, and being a gas, the oxygen passed through 
the connecting tube and bubbled up through the water of 
the bottle, accumulating at the upper surface, and by pressure 
forcing water out of the bottle. After the bottle was about 
half filled with oxygen imprisoned above the water, Pouchet 
took a pinch of hay that had been heated to a high tempera- 
ture in an oven, and with a pair of sterilized forceps pushed 
it underneath the mercury and into the mouth of the bottle, 
where the hay floated into the water and distributed itself. 
He thus produced a hay infusion in contact with pure oxy- 
gen, and after a few days this hay infusion was seen to becloudy 
and turbid. It was, in fact, swarming with micro-organisms. 
Pouchet pointed with triumphant spirit to the apparently 
rigorous way in which his experiment had been carried on: 
“Where,” said he, “does this life come from? It can not 
come from the water which had been boiled, destroying all 
living germs that may have existed in it. It can not come 
from the oxygen which was produced at the temperature 
of incandescence. It can not have been carried in the hay, 
which had been heated for a long period before being intro- 
