ing once as low as 106 deg.,
reaching 116 deg. on three occasions, 118 deg. on one, and 119 deg. on two. The
result was quite the same as that just recorded. The higher
temperatures proved perfectly incompetent to develope life.

Taking the actual experiment we have made as a basis of calculation,
if our 940 flasks were opened on the hayloft of the Bel Alp, 858 of
them would become filled with organisms. The escape of the remaining
82 strengthens our case, proving as it does conclusively that not in
the air, nor in the infusions, nor in anything continuous diffused
through the air, but in discrete particles, suspended in the air and
nourished by the infusions, we are to seek the cause of life. Our
experiment proves these particles to be in some cases so far apart on
the hayloft as to permit 10 per cent of our flasks to take in air
without contracting contamination. A quarter of a century ago Pasteur
proved the cause of 'so-called spontaneous generation' to be
discontinuous. I have already referred to his observation that 12 out
of 20 flasks opened on the plains escaped infection, while 19 out of
20 flasks opened on the Mer de Glace escaped. Our own experiment at
the Bel Alp is a more emphatic instance of the same kind, 90 per cent
of the flasks opened in the hayloft being smitten, while not one of
those opened on the free mountain ledge was attacked.

The power of the air as regards putrefactive infection is incessantly
changing through natural causes, and we are able to alter it at will.
Of a number of flasks opened in 1876 in the laboratory of the Royal
Institution, 42 per cent. were smitten, while 58 per cent. escaped.
In 1877 the proportion in the same laboratory was 68 per cent.
smitten, to 32 intact. The greater mortality, so to speak, of the
infusions in 1877 was due to the presence of hay which diffused its
germinal dust in the laboratory air, causing it to approximate as
regards infective virulence to the air of the Alpine loft. I would
ask my friend to bring his scientific penetration to bear upon all the
foregoing facts. They do not prove spontaneous generation to be
'impossible.' My assertions, however, relate not to 'possibilities,'
but to proofs, and the experiments just described do most 'distinctly
prove the evidence on which the heterogenist relies to be written on
waste paper.

My colleague will not, I am persuaded, dispute these results; but he
may be disposed to urge that other able an