TRANSCRIBER'S NOTE Italic text is denoted by _underscores_. Bold text is denoted by =equal signs=. Obvious typographical errors and punctuation errors have been corrected after careful comparison with other occurrences within the text and consultation of external sources. Misspellings in the text, and inconsistent or archaic usage, have been retained. PRINCIPLES OF PUBLIC HEALTH A SIMPLE TEXT BOOK ON HYGIENE PRESENTING THE PRINCIPLES FUNDAMENTAL TO THE CONSERVATION OF INDIVIDUAL AND COMMUNITY HEALTH BY THOS. D. TUTTLE, B.S., M.D. SECRETARY AND EXECUTIVE OFFICER OF THE STATE BOARD OF HEALTH OF MONTANA [Illustration: (publisher's colophon)] YONKERS-ON-HUDSON, NEW YORK WORLD BOOK COMPANY 1910 CONSERVATION OF HEALTH "Our national health is physically our greatest asset. To prevent any possible deterioration of the American stock should be a national ambition."--THEODORE ROOSEVELT. _The conservation of individual and national health is the keynote of these books_ PRINCIPLES OF PUBLIC HEALTH By THOS. D. TUTTLE, M.D., Secretary and Executive Officer of the State Board of Health of Montana. Illustrated. Cloth. vii + 186 pages. List price 50 cents, mailing price 60 cents. PRIMER OF HYGIENE By JOHN W. RITCHIE, of the College of William and Mary in Virginia, and JOSEPH S. CALDWELL, of the George Peabody College for Teachers, Nashville, Tennessee. Illustrated. Cloth. vi + 184 pages. List price 40 cents, mailing price 48 cents. PRIMER OF SANITATION By JOHN W. RITCHIE. Illustrated. Cloth. vi + 200 pages. List price 50 cents, mailing price 60 cents. HUMAN PHYSIOLOGY By JOHN W. RITCHIE. Illustrated in black and colors. Cloth. vi + 362 pages. List price 80 cents, mailing price 96 cents. WORLD BOOK COMPANY CASPAR W. HODGSON, _Manager_ YONKERS-ON-HUDSON, NEW YORK _Copyright, 1910, by World Book Company. All rights reserved_ INTRODUCTION The earliest history of remote ages describes methods employed in combating disease, and down through all the centuries the struggle against infection has been going on. The science of health as applied in recent years reveals wonderful progress in the avoidance of disease, and in the control of the violent epidemics by which in the past nations were almost exterminated. Modern methods of hygiene and sanitation as applied to public health have robbed smallpox and diphtheria of their death-dealing power; cholera and yellow fever have been forced to retreat before the victorious hosts of applied medical science; tuberculosis, the greatest foe of human life, is slowly but surely receding before the determined efforts of modern preventive medicine.