_Fluids not boiled, but half-filling hermetically Sealed Flasks, containing Ordinary Air._ *No. XXXVIII.--Turnip Infusion* in ten hours showed a slight amount of turbidity. After forty-eight hours this was very well-marked: there was a thick pellicle on the surface, and, in addition, a small amount of deposit. On examination, the fluid and the pellicle were found to contain an abundance of _Bacteria_, _Vibriones_ and _Leptothrix_ filaments. *No. XXXIX.--Turnip Infusion + 1/20 of Carbolic Acid* after eight days showed no appreciable alteration in appearance,[64] no trace of pellicle or deposit. When examined microscopically, however, the fluid was found to contain some very minute _Bacteria_, though they were by no means abundant. [64] It had been rendered turbid from the first, by the carbolic acid. *No. XL.--Hay Infusion* had become quite turbid in twenty-four hours, and several shades lighter in colour. After forty-eight hours the colour of the infusion was still lighter; there was more turbidity, and some sediment. On microscopical examination, the fluid was found to contain an abundance of _Bacteria_, _Vibriones_ and short _Leptothrix_ filaments. *No. XLI.--Hay Infusion + 1/20 of Carbolic Acid* showed no apparent change[65] after forty-eight hours, and when examined microscopically it revealed no trace of _Bacteria_, or other organisms. The neck of the flask was then again closed. On the twelfth day the fluid had still undergone no change in appearance, and when examined microscopically, it still showed no trace of organisms, though the fluid was--as it had been at the time of the first examination--full of minute, undissolved particles of carbolic acid. [65] The fluid had been rendered paler and turbid from the first, by the addition of the carbolic acid. _Fluids boiled for five minutes, and half-filling hermetically Sealed Flasks containing Ordinary Air._ *No. XLII.--Hay Infusion*, after forty-eight hours, showed no change, and continued to remain quite clear and free from deposit until the twelfth day, when it was examined microscopically. No organisms of any kind could be detected. *No. XLIII.--Hay Infusion + 1/20 part of Carbolic Acid* showed no apparent change[66] for the first five days, though, on the sixth day, a slight deposit was noticed at the bottom of the flask. The deposit had increased, and was well-marked by the twelfth day, when, on microscopical examination, there were found amongst the granular flakes of the deposit, _Torulæ_ of several varieties of size and shape. Many were spherical, others ovoid, or having an elongated oat-like shape: some were of the ordinary colour, and others were brownish in tint. The variety was most striking. No _Bacteria_ were seen, though there were multitudes of active particles which seemed to differ from the minute spherules of undissolved carbolic acid.