BACTERIA: the family name which includes a great many of the smallest varieties of micro-organisms or "microbes"—minute vegetable growths. They are found in three chief forms—round, rod-shaped and spiral—but as a class they are dis tinguished by their reproduction by fission—the full grown bacterium, except in a few cases, multiplying by dividing itself instead of producing others by budding (as yeasts) or by seeds or spores (as molds). They are universally recognized as of vegetable nature but some types are motile, the power of movement being often due to lidix-like processes called flagella. They are so small that they are discernible only by microscopes of high power—even the width of the finest needle would, compared to a bacterium, look like the width of a man's thumb beside a speck of dust. They are as a class the most important both for good and evil, of all microbes, the most numerous, the most vigorous—and the most difficult to control, for where the condi tions are favorable, millions can result within twenty-four hours from a single active specimen left undisturbed. They are present everywhere that life is found, and some of them are always at work in all kinds of moist food unless hermetically sealed or held at the freezing or boiling points. Freezing will stop their increase but only heat considerably above the boiling point, or long continued boiling, is a sure destroyer of all kinds.
Bacteria are found in great numbers also in various parts of the human body, but under normal conditions the presence there of some types is not only harmless, but absolutely necessary to health and life—for there are, from the human stand point, both "good" and "bad" bacteria, and we need the former to counteract the latter.
In addition to their functions in the human body—which subject belongs rather in the province of the physician than the layman—and their value in the gen eral economy of the universe—which is too wide a subject for discussion here- bacteria, properly controlled, are of great value in the production of many foods.
Their presence in various articles assists digestion by the chemical changes effected and also by producing flavors which stimulate the proper secretion of the digestive fluids which are not excited by flavorless articles of diet.
Some varieties, for example, are almost indispensable adjuncts of butter and cheese making. The "ripening" of cream before churning, is merely waiting for chemical changes to be effected by the growth and increase in it of good bacteria. One thousand million of bacteria to the square inch is a conservative estimate for well ripened cream. Butter made from cream too fresh, and therefore deficient in bacterial life, is flavorless. This ripening of cream is not new—though the knowledge of the cause of the change is. Long before the presence and activity of bacteria were discovered, the butter maker used to set his cream aside and allow his un suspected helpers to ripen it before he commenced churning. Another of the secrets of good butter making is though to know how far to let this change continue, for if overdone the cream is spoiled.
Many bacteriologists have made a study of the production of the best kind of bacteria for the use of butter-makers, and certain varieties can now be procured in open market under the name of "Pure-Cultures." These are used in much the same manner as yeast is used by bakers.
In the manufacture 'of cheese, bacteria play an even more important part—in fact, its manufacture without them is inconceivable, as the flavors for which cheeses are prized are directly attributable to bacterial agencies—though in some cases, as Brie, Camembert, Gorgonzola, Roquefort and Stilton, credit must also be given to the employment of special "mold" microbes. The production and sale of bacteria for cheese making has reached an active stage in Europe and it is only a question of time when it will be possible to set cultures for all the choicest imported cheeses at work in local American dairies.