WHAT IS A FERMENT?--Ferments, of which there are many varieties in nature, are minute living organisms analogous to the microscopic objects called bacteria or microbes, [Footnote: There is no well-defined limit between ferments and bacteria, any more than between ferments and fungi, or again, between fungi and bacteria. Their smaller size is the principal difference which separates bacteria from ferments, although there are bacteria of large size, such as are so frequently found in the mouth of even a healthy man, and which much resemble in their mode of growth some of the lower fungi.--Trouessart.] of which we have heard much in late years, especially in connection with the famous researches and experiments of the great French investigator, M. Pasteur. He tells us that "Every fermentation has its specific ferment. This minute being produces the transformation which constitutes fermentation by breathing the oxygen of the substance to be fermented, or by appropriating for an instant the whole substance, then destroying it by what may be termed the secretion of the fermented products." [Footnote: What we call spontaneous fermentation often occurs, as when apple juice turns to hard cider by simple exposure to the air. Science teaches us, however, that this change is always effected by the action of the busy little ferments which, wandering about, drop into the liquid, begin their rapid propagation, and, in the act of growing, evolve the products of the fermentation. "If the above liquids be left only in contact with air which has been passed through a red-hot platinum tube, and thus the living sporules destroyed; or if the air be simply filtered by passing through cotton wool, and the sporules prevented from coming into the liquid, it is found that these fermentable liquids may be preserved for any length of time without undergoing the slightest change."--Roscoe.] The effect, therefore, of fermentation is to change entirely the character of the substance upon which it acts; hence it is an error to assume that fermented liquors, as beer, wine, and cider, are safe drinks because the grains or fruits from which they are produced are healthful foods.