What is the function of bacteria in the economy of nature? It would be surprising if such a menace to human life as some species of bacteria have proved themselves to be had no other place among the forces of nature than to prevent the too rapid increase of the human race on this earth, as our forefathers believed. It is gratifying, and quite satisfying to a revengeful spirit, to learn from the modern laboratory that the special and only function of the bacterium is to perform the duties of a universal scavenger. It is always seeking to decompose animal and vegetable matter. It lives on filth, riots in it, and dies when deprived of it. It enters the human body only in search of filth, and if it finds none it does the person no harm, and dies either from the want of food or by starvation, or escapes from the body, or secretes itself where it may safely await the creation of decomposing matter, when it will begin its life-work. Thus, there may be and doubtless is at all times a great variety of bacteria of a virulent type, quiescent in our bodies only for the time that they find no decaying matter adapted to their special tastes or wants. It is a most interesting fact, therefore, that this most deadly foe of man becomes dangerous only when the latter is harboring in his body waste or decomposing matters that are slowly poisoning him. It is in the process of digesting this material that the bacterium excretes poisons--toxins--of the most virulent nature, which are absorbed into the blood of the human victim, creating the condition popularly known as blood poisoning. Bacteria perform a most important function in the economy of nature, viz., the conversion of decaying and dead matter into food for plants. Biologists assert that without bacteria plant life on the earth would be scanty or entirely wanting; they are the natural intermediaries between plants and animal in point of food production. They are therefore called scavengers, because they live on decomposing matter; but in the very act of digesting such waste they convert it into products essential to plant life (carbon dioxide and ammonia) and by their excretions restore to vegetation its chief supply of food. It appears on the same authorities that bacteria not only assist materially in maintaining vegetable and animal life on this planet, but “in the arts and industries they are as essential to modern economic life as are the ingenious mechanical inventions of men. Many secret processes now in use in the arts and manufactures are but devices to harness these natural forces. Thus in the manufacture of linen, hemp, and sponges, in the butter, cheese, and vinegar industries, in tobacco-curing, etc., bacteria play an important rôle.” [Sidenote: Bacteria for Every Condition]