SPONTANEOUS GENERATION. 575 
in tins which have lain perfectly good for sixty-three years 
in the Royal Institution. Modern tins, subjected to the 
same test, yielded the same result. From time to time, 
moreover, during the last two years, I have placed glass 
tubes, containing clear infusions of turnip, hay, beef, and 
mutton, in iron bottles, and subjected them to air-pressures 
varying from ten to twenty-seven atmospheres pressures, 
it is needless to say, far more than sufficient to tear a 
preserved meat tin to shreds. After ten days these infusions 
were taken from their bottles rotten with putrefaction 
and teeming with life. Thus collapses an hypothesis 
which had no rational foundation, and which could never 
have seen the light had the slightest attempt been made to 
verify it. 
Our fifty-four vacuous and pellucid flasks also declare 
against the heterogenist. We expose them to a warm 
Alpine sun by day, and at night we suspend them in a 
warm kitchen. Four of them have been accidentally 
broken; but at the end of a month we find the fifty 
remaining ones as clear as at the commencement. There 
is no sign of putrefaction or of life in any of them. We 
divide these flasks into two groups of twenty-three and 
twenty-seven respectively (tin accident of counting rendered 
the division uneven). The question now is whether the 
admission of air can liberate any generative energy in the 
infusions. Our next experiment will answer this question 
and something more. We carry the flasks to a hayloft, 
and there, with a pair of steel pliers, snip off the sealed 
ends of the group of three-and-twenty. Each snipping off 
is of course followed by an inrush of air. We now carry 
our twenty-seven flasks, our pliers, and a spirit-lamp, to a 
ledge overlooking the Aletsch glacier, about 200 feet 
above the hayloft, from which ledge the mountain falls 
almost precipitously to the northeasc for about a thousand 
feet. A gentle wind blows toward us from the northeast 
that is, across the crests and snow-fields of the Oberland 
mountains. We are therefore bathed by air which must 
have been for a good while out of practical contact with 
either animal or ^vegetable life. I stand carefully to 
leeward of the flasks, for no dust or particle from my 
clothes or body must be blown toward them. An assistant 
ignites the spirit-lamp, into the flame of which I plunge 
the pliers, thereby destroying all attached germs or 
