But our century opens with a far brighter outlook for the race. Elementary forces which, through ignorance of their true functions in the economy and conservation of nature, were permitted in the past to expend their energy in the destruction of life, have been revealed by science to be man’s most helpful agents in the promotion of comfort, health, and longevity. Electricity was for ages only a thunderbolt, an object of terror, and an agent of destruction, visiting the human residence only to kill its owner and burn the structure. To-day the same natural force is man’s most obedient and humble servant, quietly visiting his home to furnish him heat and light, annihilating time in the transactions of business, and transporting him from place to place as on the lightning’s wings. So the bacterium, once the terror of mankind as the invisible and apparently unknowable cause of devastating pestilences, proves to be the useful purveyor of the by-products of man’s digestion of waste matter which is thereby converted into food for plants. It visits man in the pursuit of its humble calling to obtain his contribution to the sum total of plant food. It searches every tissue, every organ, every recess, however obscure, but so stealthily that its coming and going and its immediate presence are not known if absolute cleanliness of the body exists. It is only when dying tissues or organs, or accumulations of dead matter, are found that its presence becomes known. Even then it would prove harmless and its presence would be unrecognized if its excretions of plant food (toxins) were not necessarily absorbed and did not enter the circulation, thus poisoning the body it is relieving of dead matter. [Sidenote: Man’s Defenses] Briefly, what are man’s defenses against bacteria? Chiefly two, viz., first, killing it by depriving it of food; and, second, killing it directly by what are known as germicides. The first method is effected by cleanliness of the person. It may be affirmed that cleanliness, without and within, absolutely protects every man, woman, and child from the most common disease-producing bacteria. It is not sufficient to keep the skin clean by daily baths, while the mouth, nose, throat, and other internal surfaces and organs are covered or filled with effete matter. We must be every whit clean if we would escape the results of the scavenging processes of bacteria of some variety or species.