6 HISTORY OF MICROBIOLOGY. 



of the Seine, and subsequently from dust, manure, and other substances. 

 Later researches have shown that these thermophilic organisms play im- 

 portant roles in various fermentations. 



The ninth decade of the last century was prolific in important bac- 

 teriological events. Discovery followed discovery in rapid succession. 

 In 1880, Laveran, a French military surgeon, discovered the protozoon of 

 malaria; in 1881 Robert Koch introduced the poured gelatin and agar 

 plate, which made it possible to obtain pure cultures without difficulty. 

 Investigators were quick to take advantage of this method; and notable 

 results followed. Eberth and Gaffky discovered the bacillus of typhoid 

 fever, and succeeded in growing it in culture media. In 1882, Loeffler 

 and Schlitz discovered the bacterium which causes glanders; and in the 

 following year Koch isolated the vibrio of Asiatic cholera from the in- 

 testines of cholera patients. In 1883 Klebs described the diphtheria 

 bacterium; and, in 1884, LoefBer grew the organism in pure culture. 



In 1884, Koch published his results on the etiology of tuberculosis, 

 in a paper which will remain as a classical master-piece of bacteriological 

 research, owing to the difficulty of the task and the thoroughness of the 

 work. Not only did Koch show the tubercle bacterium by appropriate 

 staining methods, but he succeeded in obtaining pure cultures of it and in 

 producing tuberculosis by inoculation with his isolated cultures. 



In 1885, Nicolaier observed the tetanus bacillus in pus produced by 

 inoculating mice and rabbits with soil; later, in 1889, Kitasato isolated 

 this organism, and showed that the cause of the failure in earlier attempts 

 to isolate it were due to the fact that it could grow only in the absence of 

 free oxygen. The specific infecting agents in pneumonia were discovered 

 by Friedlander and Fraenkel about this time, as were also several organ- 

 isms associated with inflammation and suppuration, such as the Strep- 

 tococcus pyogenes and the Staphylococcus pyogenes, discovered by Rosen- 

 bach, and the green pus germ (Pseudomonas pyocyanea) by Gessard. 



Whilst these discoveries were taking place, largely in Germany, Pas- 

 teur had been engrossed with his prophylactic studies. In 1880, he dis- 

 covered a method of vaccination against fowl cholera; and in 1881 he 

 published his method of vaccination against anthrax. On a farm at 

 Pouilly le Fort, sixty sheep were placed at Pasteur's disposal; ten of these 

 received no treatment, and twenty-five were vaccinated. Some days 

 afterward the latter were inoculated with virulent anthrax, and also 

 twenty-five which had received no vaccine. The twenty-five non-vacci- 



