Preface 9 



change in the title, offer to old friends and future patrons a 

 work that shall endeavor to meet all modern requirements : 



By describing all the pathogenic micro-organisms of 

 importance in human medicine, whether they be bac- 

 teria or protozoa; 



By teaching the laboratory technic with reference to 

 the needs of medical students and practitioners; 



By bringing each micro-organism under consideration 

 into a historic, geographic, biologic, and pathologic 

 setting ; 



By dwelling upon the anatomic and physiologic disturb- 

 ances referable to the various micro-organisms; 



By describing the lesions occasioned by the different 

 micro-organisms; and, 



By explaining such methods of diagnosis and treatment 

 as grow out of the knowledge of microbiology in gen- 

 eral and of the micro-organisms in particular. 



JOSEPH McFARLAND. 

 PHILADELPHIA, September, 1912. 



