some misconceptions as to the present state of knowl- 

 edge on this subject. It shall be, accordingly, my effort 

 to present in these lectures no original investigations, no 

 theories nor views, but simply the facts already estab- 

 lished, and the deductions incident thereto an effort 

 which I am encouraged to undertake by some familiarity 

 with pertinent literature, and by some little practical 

 knowledge of the methods and manipulations involved. 



In order to discuss intelligibly the more recent and 

 familiar subjects, such as the r61e of the bacillus tuber- 

 culosis, we must bear in mind certain facts, less sensa- 

 tional and perhaps less widely known, concerning the 

 life-history of microscopic parasites. 



Although even the early microscopists. beginning with 

 Leeuwenhoeck (1675), observed and studied bacteria; 

 although these minute bodies were observed in animals 

 dead of septic infection by Fuchs, in 1848, and in the 

 blood of sheep dead of anthrax by Brauell and Davaine, 

 in 1849 an d 1850, no effort appears to have been made 

 to establish a genetic relation between the plants and the 

 disease until the publication of Pasteur's work on fer- 

 mentations, in 1 86 1. Then the bacteria which had been 

 the unenvied monopoly of biologists suddenly acquired 

 deep interest for pathologists. The experimental work 

 on septic infection, by Mayerhofer, Coze and Feltz, Rind- 

 fleisch, Waldeyer, and Recklinghausen, in 1865, 1866, 

 and 1867, drew the attention df the medical public to the 

 subject Meanwhile Lister, impressed with the results 

 of Pasteur's work, and desperate (as I was informed by 

 a Glasgow neighbor of his) at the death from pyaemia 

 of several cases in rapid succession, anticipating the te- 

 dious progress of experimental science, submitted the 

 question to empiric arbitration on the operating table. 

 His clinical results revolutionized surgical methods on 

 the one hand and infused new vigor into experimental 

 pathologists on the other ; the number of workers and 

 of works so rapidly increased that to-day simple mention 

 of the literature of this subject would be the work of 

 hours, I deem it, therefore, inexpedient to attempt, in 



