THE PRINCIPLES OF 3827 HYGIENE A Practical Manual for Students, BY D. H. BERGEY, A.M., M.D. First Assistant, Laboratory of Hygiene, and Assistant Professor of ILLUSTRATED FIFTH EDITION, THOROUGHLY REVISED PHILADELPHIA AND LONDON W. B. SAUNDERS COMPANY 1914 Copyright, 1901, by W. B. Saunders and Company. Revised, reprinted, and Copyright, 1914, by W. B. Saunders Company. PRINTED IN AMERICA PRESS OF W. B. SAUNDERS COMPANY PHILADELPHIA TA 349 1914 PREFACE TO THE FIFTH EDITION. THE subjects which have been considered in this book are practically all undergoing marked changes, so that it becomes necessary from time to time to revise statements which embodied our knowledge a few years ago. In the present edition the attempt has been made to bring the subject matter up to date as far as possible. It is not an easy task to keep in touch with all the various lines of investigation and administration which engage the attention of the men in the laboratory as well as those in the field. The helpful reviews of the fourth edition have aided materially in directing the revision, and grateful acknowledgment is made for the valuable criticisms expressed by the reviewers. September, 1914. D. H. B. 118219 OCT 1 1 1950 7 |