PREFACE 



This work is an attempt to reveal to the reader 

 those living beings of the Invisible World which 

 most concern us. The author is not aware that 

 any other work, similar in plan and scope, has 

 been published. Fragmentary parts of the general 

 subject have been treated, but even these have usu- 

 ally appeared in so technical terms as to be of 

 little, if any, avail to the general public. The aim 

 here has been to cover the entire field, and in so 

 plain and simple language that whoever reads may 

 understand. 



With this aim in view, Microbes In General are 

 first considered, their nature, functions, origin. 



Invisible Friends come next, their character- 

 istics, where they live, what they do for us, how 

 they do it. 



This prepares the way the better to understand 

 Our Invisible Foes, the chief purpose of this book. 

 Forty-four different germs are treated as the active 

 causes of forty-four different diseases. A brief 

 chapter is devoted to each germ ; showing what the 

 germ is, how it enters the body, how it causes the 

 disease, how, if possible, the disease may be cured, 

 and, better still, how to prevent the disease. 



Protection Against Our Invisible Foes is next in 

 order, and has its full share of attention. 



284527 



