INTRODUCTION. 29 



Neisser, in the same year (1879), discovered the 

 " gonococcus " in gonorrhoeal discharges. 



In 1880, Eberth and Koch independently observed 

 the typhoid bacillus, but it was not until 1884 that 

 Gaffky published his important researches, and proved 

 the etiological relation of this bacillus to typhoid fever. 



In the same year (1880) several important communi- 

 cations in bacteriological research appeared. Pasteur 

 published his discovery of the bacillus of fowl cholera 

 and his investigations upon the attenuation of the virus 

 of anthrax and of fowl cholera, and upon protective 

 inoculation against these diseases. 



Sternberg and Pasteur independently observed (1880) 

 a pathogenic micrococcus in saliva, which was subse- 

 quently proved by Fraenkel and others (1885) to be 

 the organism most commonly associated with acute 

 croupous pneumonia the " diplococcus pneumoniae" 

 and now recognized as the usual cause of that disease. 



In 1881, Koch made his fundamental researches upon 

 pathogenic bacteria, the result of which was the estab- 

 lishment of a foundation upon which bacteriology of the 

 future was to rest. He introduced solid culture media 

 and the " plate method 7 ' for obtaining pure cultures, 

 and showed how different organisms could be isolated, 

 cultivated independently, and by inoculation of pure 

 cultures into susceptible animals made, in many cases, 

 to reproduce the specific disease of which they were the 

 cause ; and he laid down the laws by which it may be 

 proved that a micro-organism is the specific cause of 

 a disease. It was in the course of this work that the 

 Abbe system of substage condensing apparatus was first 

 used in bacteriology and that Weigert's method of 

 staining was generally employed. 



