260 



BACILLI PATHOGENIC IN MAN. 



Demonstra- 

 tion of the 

 inoculability 

 of tuber- 

 culosis. 



Method of 

 demonstrat- 

 ing 1 the 

 tubercle 

 bacilli micro- 

 scopically. 



Bacillus tuberculosis. 



Klencke, and at a later period Villemin, were the 

 first to show that the affected organs from tuberculous 

 human beings, and from animals suffering from perl- 

 sucht, set up tuberculosis when inoculated on animals ; 

 they thereby proved the infective nature of tuberculosis, 

 and provided a justifiable basis for the supposition that 

 in this disease also the exciting agent was an organised 

 living body. The infective experiments were subse- 

 quently repeated in a convincing manner, more espe- 

 cially by Cohnheim and Salomon sen, and later by 

 Darnsch, who employed the eyes of rabbits as the seat 

 of inoculation, and were able to set up tuberculosis of 

 the iris by inoculation of tuberculous material into the 

 eye, the disease spreading from thence to other organs. 

 In spite of these experiments the nature and the ulti- 

 mate cause of tuberculosis was for a long time obscure, 

 as the attempts to find, even with the most careful 

 microscopical examination, any organised bodies in 

 tuberculous organs which could be looked on as the 

 exciting agents of the disease were not successful, and 

 as also experiments on the cultivation of the sup- 

 posed organised virus did not lead to any definite 

 result. It was not till a few years ago that by means 

 of Koch's classical investigations we obtained a com- 

 plete insight into the etiology of this disease ; a result 

 which so much the more deserves our most complete 

 admiration , because entirely new and special methods 

 were necessary as well for the microscopical examina- 

 tion as also for the cultivation of the micro-organisms, 

 and because the whole investigation was laid before 

 us in such a complete form that in respect of this 

 question the points as to the etiology of tuberculosis 

 are scarcely capable of any further important expansion. 

 The following description is consequently in the main 

 based only on Koch's work on tuberculosis. 



In the first place Koch succeeded in demonstrating 

 the presence of peculiar bacilli in the most various 

 tuberculous affections by means of a special method of 

 staining. While no micro-organisms could be demon- 



