I have made many experiments of this kind with different solutions, some of which I will now record. Owing to the different behaviour of the same fluids under different conditions, we are enabled to draw some most important conclusions; and owing to the different behaviour of different fluids under these respective conditions, our attention is strongly drawn to other facts which ought considerably to influence our judgment as to the relative merits of the two doctrines concerning the cause of fermentation and putrefaction.
COMPARATIVE EXPERIMENTS.
In the following experiments, each fluid (unless a statement is made to the contrary) was boiled continuously for ten minutes, after having been placed in its flask. Then, with the neck either open, sealed, or plugged, the bulb of the flask was immersed in a water-bath maintained at a temperature of 80°–95° F., during both day and night.[47]
First Set of Experiments (I.–XV.).
a. Fluid exposed to Air in a Flask with a short Open Neck.
No. I.—Urine in twenty-four hours was still clear and free from deposit. In forty-four hours the fluid was very slightly turbid, and on microscopical examination Bacteria and Torulæ were found, though not in very great abundance. In sixty-eight hours the fluid was quite turbid.
No. II.—Hay Infusion in twenty-four hours was still clear. In forty-four hours the fluid was very turbid, and a drop on examination showed multitudes of Bacteria of different kinds, exhibiting languid movements. In sixty-eight hours the turbidity had become much more marked, and there was also a certain amount of sediment.
No. III.—Turnip Infusion in twenty-four hours showed a very slight degree of turbidity. A drop examined microscopically revealed a number of very minute, but very active, Bacteria. In forty-four hours the turbidity had become very well marked.