INTRODUCTION 5 



In 1876 Robert Koch first demonstrated that 

 anthrax in cattle was due to the Bacillus anthracis. 



Until 1882 the methods of study and observation 

 of bacteria were so imperfect that it was almost 

 impossible to isolate a single species, and the process 

 was attended with so much uncertainty that inves- 

 tigators were often not sure whether they were 

 dealing with one or more species. 



At this time Koch invented the solid culture 

 media, whereby it became possible to easily isolate 

 a single species, Weigert suggested the use of ani- 

 line dyes as a means of differentiation, and the 

 use of animals as a means of obtaining pure cul- 

 tures began. 



From Koch's series of brilliant investigations, 

 bacteriology is said to have been placed within the 

 reach of men who were not geniuses like Pasteur 

 and himself, and may be justly said to have had 

 its birth. 



The development of bacteriology in the last 

 twenty-five years has been marvelously rapid, 

 causing an almost complete revolution in the whole 

 practice of medicine, and opening methods of 

 agriculture and other industries which have proved 

 of infinite benefit to the whole world. The fact 

 that until Pasteur's researches in the middle of 



