Our Servants.—­We scarcely know what services microbes may render us, yet the study of them, which has but recently been begun, has already shown, through the remarkable labors of Messrs. Pasteur, Schloesing and Muntz, Van Tieghem, Cohn, Koch, etc., the importance of these organisms in nature.  All of us have seen wine when exposed to air gradually sour, and become converted into vinegar, and we know that in this case the surface of the liquid is covered with white pellicles called “mother of vinegar.”  These pellicles are made up of myriads of globules of Mycoderma aceti.  This mycoderm is the principal agent in the acidification of wine, and it is it that takes oxygen from the air and fixes it in the alcohol to convert it into vinegar.  If the pellicle that forms becomes immersed in the liquid, the wine will cease to sour.

The vinegar manufacturers of Orleans did not suspect the role of the mother of vinegar in the production of this article when they were employing empirical processes that had been established by practice.  The vats were often infested by small worms ("vinegar eals”) which disputed with the mycoderma for the oxygen, killed it through submersion, and caused the loss of batches that had been under troublesome preparation for months.  Since Mr. Pasteur’s researches, the Mycoderma aceti has been sown directly in the slightly acidified wine, and an excellent quality of vinegar has thus been obtained, with no fear of an occurrence of the disasters that accompanied the old process.

Another example will show us the microbes in activity in the earth.  Let us take a pinch of vegetable mould, water it with ammonia compounds, and analyze it, and we shall find nitrates therein.  Whence came these nitrates?  They came from the oxidation of the ammonia compounds brought about by moistening, since the nitrogen of the air does not seem to combine under normal conditions with the surrounding oxygen.  This oxidation of ammonia compounds is brought about, as has been shown by Messrs. Schloesing and Muntz, by a special ferment, the Micrococcus nitrificans, that belongs to the group of Bacteriacae.  In fact, the vapors of chloroform, which anesthetize plants, also prevent nitrification, since they anaesthetize the nitric ferment.  So, too, when we heat vegetable humus to 100 deg., nitrification is arrested, because the ferment is killed.  Finally, we may sow the nitric ferment in calcined earth and cause nitrification to occur therein as surely as we can bring about a fermentation in wine by sowing Mycoderma aceti in it.

The nitric ferment exists in all soils and in all latitudes, and converts the ammoniacal matters carried along by the rain into nitrates of a form most assimilable by plants.  It therefore constitutes one of the important elements for fertilizing the earth.