PERSISTENCE OE PUTREFACTIVE AND INFECTIVE ORGANISMS. 
167 
moderate it, I sometimes partially turned off the gas, thus lowering the temperature of 
the room 10° or more. The contraction of the air within the closed chambers followed 
as a matter of course, and the bent tubes being open, I thought the entrance of the 
external air might be sufficiently rapid to carry germs along with it. 
A new chamber of six tubes was therefore prepared upstairs, three of its tubes being 
charged with cucumber- and three with turnip-infusion on the 27th of November. The 
pipette funnel and the bent tubes were plugged above with cotton-wool, which was not 
removed from them afterwards. I took care, moreover, not to alter the gas-stoves in 
any way. My care was nugatory. In three days every tube of the six was laden with 
life. Another chamber of six tubes, charged on the 30th of November with cucumber- 
infusion, and two additional ones prepared on December 1st, shared the same fate. 
Slices of cucumber were next digested for three hours; the infusion was filtered, 
boiled, and such precipitated matter as appeared on boiling was removed by refiltering. 
The liquid thus prepared was introduced into five thick glass tubes, which were herme- 
tically sealed, placed in a cold oil-bath, gradually heated to 230°, and maintained at 
that temperature for a quarter of an hour. The tubes being removed and permitted 
to cool, the infusion was introduced into a chamber of six tubes, and boiled there for 
five minutes. 
The superheating of the infusion did not even retard the development of life, for in 
less than two days every tube in the chamber swarmed with Bacteria. Thus far, then, 
every attempt at a solution was defeated. 
But why, it may be asked, attempt such solutions'? Was it mere prejudice against 
the doctrine of spontaneous generation that prevented me from frankly submitting to 
the apparent logic of facts, and admitting the experiments just recorded to be a demon- 
stration of the doctrine'? By no means. The only prejudice I feel is the wholesome 
repugnance to accepting momentous conclusions on insufficient grounds. Hume’s 
celebrated argument has its application here. Taking antecedent experience fully 
into account, it was easier for me to believe my knowledge imperfect, or my present 
work erroneous, than to believe the doctrine of spontaneous generation true. 
§11. New Experiments on Animal Infusions. Contradictory results. 
In the course of this inquiry I was continually reminded of last year’s experiments, 
when the most complete immunity from Bacterial or fungoid life was so readily secured. 
I had operated many times with turnip, never finding the least difficulty as to its steriliza- 
tion. It is certain that the care bestowed in preparing the turnip-infusion on the 20th 
of November, 1876, was greater than that bestowed upon the same infusion in 1875. 
But whereas the latter was invariably sterilized by five minutes’ boiling, remaining 
afterwards as pellucid as distilled water, the former, three days after its preparation, 
became thickly turbid and swarming with life. I extended the present inquiry to other 
substances whose deportment was familiar to me last year, some of whose infusions, indeed, 
still remain with me as clear as they were on the day of their preparation. 
2 B 2 
