Sixth Set of Experiments (XLVIII.–LXV.).
Ammoniacal Solutions, unboiled, and exposed to Ordinary Air in a Corked Bottle.[70] (Temp. 60°–65° F.)
No. XLVIII.—Ammonic Acetate Solution.—On the tenth day the fluid was still quite clear, and free from sediment.
No. XLIX.—Ammonic Oxalate Solution.—On the tenth day there was no distinct opalescence of the fluid, but a well-marked whitish flocculent deposit. On microscopical examination no Bacteria were found in the fluid, and the deposit was made up by an aggregation of blackish and colourless granules, mixed with a few crystals and a very few Torula cells—all being held together by a sort of mucoid matrix. In the midst of this matter were found two or three very small, much branched, mycelial tufts of a fungus-growth.
No. L.—Ammonic Carbonate Solution.—On the tenth day the fluid showed a very faint opalescence, with a small amount of deposit, and a partial non-coherent scum on the surface, which, on microscopical examination, was found to be composed partly of amorphous granules, and partly of minute Bacteria, mixed with small necklace-like organisms. The fluid itself contained, in suspension, a few small and sluggish Bacteria, with a minute Torula cell here and there.
No. LI.—Ammonic Tartrate Solution after twenty-four hours showed the faintest opalescence of the fluid; in forty-eight hours there was a bluish-white turbidity, and in seventy-two hours the turbidity was well marked. When examined microscopically the fluid was found to contain multitudes of very active Bacteria. On the thirteenth day the turbidity was not so well marked, though there was a very thin pellicle on the surface, and also the dirty-looking crumpled remains of another pellicle at the bottom, which, on examination, was found to be composed of an aggregation of Bacteria. The pellicle on the surface was very thin, and composed only of a single layer of Bacteria. In the fluid itself many Bacteria were seen, of medium size, and mostly sluggish in movement, though a few of them exhibited very active rotatory movements. No Vibriones, Leptothrix, or Torulæ, were found.
No. LII.—Ammonic Tartrate and Sodic Phosphate Solution after twenty-four hours showed the faintest opalescence; in forty-eight hours there was a bluish-white turbidity, which, in seventy-two hours, had become more marked. When examined microscopically multitudes of Bacteria were found whose movements were very sluggish. On the thirteenth day there was a well-marked whitish turbidity, due to Bacteria and Vibriones, a slight amount of deposit, and a firm pellicle which was found to be composed, almost wholly, of long unjointed Vibriones and unsegmented Leptothrix filaments, all of which, when separate, exhibited the most distinct eel-like movements, accompanied by an actual progression from place to place.
Ammoniacal Solutions, unboiled, and exposed to Air in a Corked Bottle, after Inoculation with a Drop of Fluid containing living Bacteria and Torulæ. (Temp. 60°–65° F.)
No. LIII.—Ammonic Acetate Solution after twenty-four hours was faintly opalescent, and in forty-eight hours showed a very slight bluish tint. In seventy-two hours it was in the same state, and, on microscopical examination, the fluid showed no distinct Bacteria or other living things, though there were a number of very minute particles distributed, singly or in small groups, throughout the fluid. On the thirteenth day there was no change in appearance, except that the sediment had somewhat increased in amount. Still, no Bacteria could be found in the fluid or the sediment,—only the above-mentioned particles, and a few somewhat larger, which resembled very minute Torulæ. Amongst the sediment, however, there were two or three very small mycelial tufts of a developing fungus.
No. LIV.—Ammonic Oxalate Solution.—On the eighth day the fluid showed a very faint opalescence, though there was a well-marked, greyish, flocculent deposit, which was found to be composed of an aggregation of colourless and blackish granules, of a multitude of minute crystalline particles (mostly diamond-shaped), and some rounded or ovoidal, thick-walled, spore-like bodies; amongst which, and enveloped in part by them, were several mycelial tufts of a fungus. A number of minute Bacteria were found distributed throughout the fluid, and also a quantity of minute star-like bodies (crystalline), about 1/12000 in diameter.