Scarcely one half of the children of our country continue in school much beyond the fifth grade. It is important, therefore, that so far as possible the knowledge which has most to do with human welfare should be presented in the early years of school life. Fisher, Metchnikoff, Sedgwick, and others have shown that the health of a people influences the prosperity and happiness of a nation more than any other one thing. The highest patriotism is therefore the conservation of health. The seven hundred thousand lives annually destroyed by infectious diseases and the million other serious cases of sickness from contagious maladies, with all their.