PREFACE TO REVISED EDITION 



It is now twenty years since this book was first pub- 

 lished and ten years since it was revised and reprinted. 

 Meanwhile many important discoveries have been made 

 concerning the nature and propagation of bacteria, and 

 many changes have taken place in the attitude of scien- 

 tific men towards the causes and restrictions of contagious 

 diseases and the promotion of personal and public health. 



The author has taken advantage of the demand for 

 another revision to rewrite, rearrange, and illustrate this 

 book in accord with the latest teachings in this branch 

 of science. 



In this edition, as in previous editions, it has been the 

 aim of the author to prepare a text-book for elementary 

 schools which should set forth clearly and tersely the more 

 important and interesting facts about our bodily life. 



It is believed that boys and girls in elementary schools 

 should have an opportunity to learn a few essential things 

 about the anatomy and physiology of their own bodies. 

 These facts in themselves are of comparatively little worth 

 unless they become the means of enabling our young folks 

 to understand thoroughly the simple laws of health and to 

 apply them intelligently to their daily living. With this 

 in mind, the author has aimed to lay marked emphasis 



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