INFECTIOUS DISEASES. 621 



tuberculosis is an infectious disease, was contained in Koch's origi- 

 nal memoir announcing his discovery. Investigations made since 

 have fully confirmed Koch's conclusions in all important particu- 

 lars. In order to show you the interest taken by bacteriologists 

 and pathologists in all that relates to the tubercle bacillus and 

 the effects of its pathogenic action, I have referred to the Jahres- 

 bericht of Baumgarten, for the year 1890, which gives abstracts of 

 all original memoirs in this field of research. The total number 

 of papers referred to, published during the year mentioned, is one 

 hundred and thirty-five. By far the greater number are pub- 

 lished in German and French journals, but the literature includes 

 a certain number of memoirs published in Russia, in Italy, in 

 Hungary, in Sweden, and in the United States. 



Another important discovery, made in 1882, is that of the ba- 

 cillus of glanders, by Loffler and Schutz. 



Koch published his discovery of the cholera spirillum (" com- 

 ma bacillus") in 1884. 



The same year (1884) Lofner discovered the diphtheria bacillus. 

 Subsequent researches have not only established the etiological 

 relation of this bacillus to the disease known as diphtheria, but 

 have given us an exact knowledge of its biological characters and 

 pathogenic action, as tested upon lower animals. 



The tetanus bacillus was discovered in 1884 by Nicolaier, a 

 student in the laboratory of Prof. Fliigge, of Gottingen. That 

 this bacillus is the cause of tetanus in man has been demonstrated 

 by the subsequent researches of numerous investigators. 



So far as human pathology is concerned, no important patho- 

 genic micro-organism has been discovered since the date last men- 

 tioned (1884) until the present year. After numerous unsuccess- 

 ful researches by competent bacteriologists, a bacillus has been 

 discovered by Pfeiffer, of Berlin, and independently by Canon, 

 which there is good reason to believe is the specific cause of epi- 

 demic influenza. 



"We have, also, a recent announcement, by Canon, of the dis- 

 covery of a minute bacillus in the blood of patients suffering with 

 measles, but the etiological relation of this bacillus has not been 

 established, and additional researches will be required before we 

 can properly estimate the value of Canon's alleged discovery. 



The brief historical review which we have made shows that 

 the etiology of a considerable number of infectious diseases has 

 been determined by the researches of bacteriologists, but it also 

 shows that other important diseases of this class are not included 

 in this list. 



Up to the present date no satisfactory demonstration of the 

 specific infectious agent has been made in any one of the eruptive 

 fevers ; and in yellow fever, my own extended researches have 



