26 Introduction 



was a period of nearly twenty-five years during which no 

 important pathogenic organisms were discovered, but during 

 which technical methods were being elaborated, making 

 possible a rapid succession of subsequent important dis- 

 coveries. 



Thus, in 1873, Obermeier discovered Spirillum ober- 

 meieri of relapsing fever. 



In 1879 Hansen announced the discovery of bacilli in 

 the cells of leprous nodules, and Neisser discovered the 

 gonococcus. 



In 1880 the bacillus of typhoid fever was observed by 

 Hberth and independently by Koch, Pasteur published his 

 work upon "Chicken-cholera," and Sternberg described the 

 pneumococcus, calling it Micrococcus pasteuri. 



In 1882 Koch made himself immortal by his discovery 

 of and work upon the tubercle bacillus, and in the same year 

 Pasteur published a work upon "Rouget du Pore," and 

 Loffler and Shiitz discovered the bacillus of glanders. 



In 1884 Koch reported the discovery of the "comma 

 bacillus," the cause of cholera, and in the same year Loffler 

 isolated the diphtheria bacillus, and Nicolaier the tetanus 

 bacillus. 



In 1892 Canon and Pfeiffer discovered the bacillus of 

 influenza. 



In 1894 Yersin and Kitasato independently isolated the 

 bacillus causing the bubonic plague, then prevalent at 

 Hong-Kong. 



A new era in bacteriology, and probably the most tri- 

 umphant achievement of scientific medicine, was inau- 

 gurated in 1890, when Behring discovered the principles of 

 the " blood-serum therapy." Since that time investigations 

 have been largely along the lines of immunity, immunization, 

 and the therapeutic serums, the names of Behring, Kitasato, 

 Wernicke, Roux, Khrlich, Metschnikoff, Bordet, Wasser- 

 mann, Shiga, Madsen, and Arrhenius taking front rank. 



The discovery of the Treponema pallidum, the specific 

 organism of syphilis, was made in 1905 by Schaudinn and 

 Hoffmann, long after clinical study of the disease had antici- 

 pated it to such an extent that when the discovery was finally 

 made it was unnecessary to modify our ideas of the disease in 

 any essential. 



In the same year, 1905, Castellani discovered the Trepo- 

 nema pertenue, the cause of frambesia or yaws. 



