PREFACE TO THE NEW EDITION 



Ten years have passed since the last (third) Edition of 

 this book appeared. Great changes have taken place since 

 that time. The phenomenal extension of the study of 

 Bacteriology, its application to the study of Public Health, 

 and to Medical and Surgical Practice ; the remarkable 

 extension of our knowledge of the chemical activity of 

 Micro-organisms ; the results achieved in the battle against 

 infectious diseases by means of accurate bacterioscopic 

 analysis and diagnosis, and by the brilliant application of 

 serum therapeutics, are matters obvious to the Biologist, the 

 Chemist, the Sanitary Expert, the Physician and Surgeon. 

 To get an idea how much the study of micro-organisms in 

 their relation to disease has extended we may state that when 

 Baumgarten's Jahresbericht — an annual review giving a 

 tolerably complete account of the work done in pathological 

 mycology — first appeared (Vol. I.) in 1886 its size was 185 

 pages; in 1892 (Vol. VII.) it had reached the size of 862 

 pages, and it has been steadily increasing since. Since 1886 

 several most important periodicals have come into existence 



