[66] The alteration in colour was less marked than in the similar mixture which had not been boiled, though the turbidity was just as obvious. _Fluids (in vacuo)--boiled for five minutes, and Flasks Sealed during Ebullition._ *No. XLIV.--Turnip Infusion*, in seventy-two hours, showed a slight turbidity, which gradually increased. On the eighth day there was a considerable quantity of flake-like sediment, and some amount of general turbidity. On the thirteenth day the vacuum was found to be still partly preserved. When the flask was opened the fluid was perceived to have a fœtid odour, and an acid re-action; and, on microscopical examination, multitudes of _Bacteria_ and _Vibriones_ were seen. In the flake-like aggregations also (made up almost wholly of these organisms) there were a number of large thick-walled spores; some already formed, and others in process of formation by coalescence. *No. XLV.--Turnip Infusion + 1/20 part of Carbolic Acid* showed no increase of turbidity[67] for the thirteen days during which it was kept under observation. Before the flask was opened it was ascertained that the vacuum was well preserved. The odour of the fluid was unaltered, and on microscopical examination no _Bacteria_, or other living things, were found.[68] [67] This fluid was whitish, and somewhat opaque, from the first. [68] For other experiments showing a similar sterility, induced by a slight acidification with acetic acid, see ‘Nature,’ 1870, No. 37, pp. 226 and 227. *No. XLVI.--Hay Infusion*, after forty-eight hours, showed no change, though, in seventy-two hours, there was perceptible a very small amount of a dirty greyish deposit. By the fifth day the deposit had slightly increased, and on the seventh day there was a trace of turbidity in the fluid. It did not undergo much further change, so that, on the twelfth day, the flask was opened. The vacuum was found to have been very slightly impaired; the odour of the fluid was almost natural, and its re-action was slightly acid. On microscopical examination of the deposit, _Bacteria_, _Vibriones_, short _Leptothrix_ filaments, and _Torulæ_, were found, though not in very great abundance.