PREFACE TO THE FIRST EDITION 



THE volume here presented is primarily a treatise on the funda- 

 mental laws and technique of Bacteriology, as illustrated by their 

 application to the study of pathogenic bacteria. 



So ubiquitous are the bacteria and so manifold their activities 

 that Bacteriology, although one of the youngest of sciences, has 

 already been divided into special fields Medical, Sanitary, Agricul- 

 tural, and Industrial having little in common, except problems of 

 general bacterial physiology and certain fundamental technical 

 procedures. 



From no other point of approach, however, is such a breadth of 

 conception attainable, as through the study of bacteria in their 

 relation to disease processes in man and animals. Through such a 

 study one must become familiar not only with the growth character- 

 istics and products of the bacteria apart from the animal body, thus 

 gaining a knowledge of methods and procedures common to the 

 study of pathogenic and non-pathogenic organisms, but also with 

 those complicated reactions taking place between the bacteria and 

 their products on the one hand and the cells and fluids of the animal 

 body on the other reactions which often manifest themselves as 

 symptoms and lesions of disease or by visible changes in the test tube. 



Through a study and comprehension of the processes underlying 

 these reactions, our knowledge of cell physiology has been broadened, 

 and facts of inestimable value have been discovered, which have 

 thrown light upon some of the most obscure problems of infection 

 and immunity and have led to hitherto unsuspected methods of 

 treatment and diagnosis. Thus, through Medical Bacteriology that 

 highly specialized offshoot of General Biology and Pathology have 

 been given back to the parent sciences and to Medicine in general 

 methods and knowledge of the widest application. 



It has been our endeavor, therefore, to present this phase of our 

 subject in as broad and critical a manner as possible in the sections 

 dealing with infection and immunity and with methods of biological 

 diagnosis and treatment of disease, so that the student and practi- 



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