&8g FRAGMENTS Of SCIKNCB. 
However this may be whatever be the state of the sur- 
face of the body, of the spores of Bacillus subtilis, they 
do as a matter of certainty resist, under some circum- 
stances, exposure for hours to the heat of boiling water. 
No theoretic skepticism can successfully stand in the wa 
of this fact, established as it has been by hundreds, if not 
thousands, of rigidly conducted experiments. 
We have now to test one of the principal foundations of 
the doctrine of spontaneous generation as formulated in 
this country. With this view, I place before my friend 
and co-inquirer two liquids which have been kept for six 
months in one of our sealed chambers, exposed to optically 
pure air. The one is a mineral solution containing in 
proper proportions all the substances which enter into the 
composition of bacteria, the other is an infusion of turnip 
it might be any one of a hundred other infusions, 
animal or vegetable. Both liquids are as clear as distilled 
water, and there is no trace of life in either of them. 
They are, in fact, completely sterilized. A rnutton-chop, 
over which a little water has been poured to keep its juices 
from drying up, has lain for three days upon a plate in our 
warm room. It smells offensively. Placing a drop of the 
fetid mutton-juice under a microscope, it is found swarm- 
ing with the bacteria of putrefaction. With a speck of 
the swarming liquid I inoculate the clear mineral solution 
and the clear turnip infusion, as a surgeon might inoculate 
an infant with vaccine lymph. In four-and-twenty hours 
the transparent liquids have become turbid through- 
out, and instead of being barren as at first they are 
teeming with life. The experiment may be repeated a 
thousand times with the same invariable result. To the 
naked eye the liquids at the beginning were alike, being 
both equally transparent to the naked eye they are alike 
at the end, being both equally muddy. Instead of putrid 
mutton-juice, we might take as a source of infection any 
one of a hundred other putrid liquids, animal or vegetable. 
So long as the liquid contains living bacteria a speck of it 
communicated either to the clear mineral solution, or to 
the clear turnip infusion, produces in twenty-four hours 
the effect here described. 
We now vary the experiment thus: Opening the back- 
door of another closed chamber which has contained for 
