PREFACE 



This little book was designed by the writer to serve the needs 

 of the medical student preparing for examination, and for the 

 prac itioner of medicine who desires to acquaint himself with the 

 principle facts of the rapidly growing science of bacteriology. An 

 effort has been made to reduce the subject matter to as concrete 

 a form as possible. 



While the literature of the subject of immunity is as vast almost 

 as the rest of bacteriology, yet it is hoped that the chapter in this 

 book on immunity gives in outline the essential accepted teachings 

 on the subject. 



Minute details of cultures and technic are not given. They 

 must be sought for in books on descriptive bacteriology. 



The author has drawn very freely from many standard text- 

 books. Many illustrations are from Kolle & Wassermann's 

 Atlas, Park and Williams, Williams, McFarland, Tyson's Prac- 

 tice and Abbott. 



The writer's best thanks are tendered to Dr. Herbert Fox of 

 the University of Pennsylvania (Pepper Laboratory) to whom 

 entire credit is due for the chapters on filterable viruses; the re- 

 arrangement of the chapters, and the new matter that has been 

 added throughout the book. 



ROBERT L. PITFIELD. 



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