CHAPTER IX. 

 TUBERCULOSIS. 



THE cause of tubercle was proved by Koch in 1882 to be 

 the organism now universally known as the tubercle bacillus. 

 Probably no other single discovery has had a more im- 

 portant effect on medical science and pathology than this. 

 It has not only shown what is the real cause of the disease, 

 but has also supplied infallible methods for determining 

 what are tubercular lesions and what are not, and has also 

 given the means of studying the modes and paths of in- 

 fection. A definite answer has been supplied in this way 

 to many questions which were previously the subject of 

 endless discussion. 



Historical. Klencke in 1843 made the statement that 

 he had produced tuberculosis in rabbits by intravenous 

 injection of tubercular material, but he only concluded from 

 these experiments that the cells of tubercles could multiply 

 and reproduce the disease, and he appears to have placed 

 little importance on the discovery. Villemin has the 

 honour of having been the first to investigate the infectious 

 character of tubercle by systematic experiments, and to 

 demonstrate the regularity with which tuberculosis can be 

 transmitted by inoculation with tubercular material. His 

 first observations were published in 1865. He produced 

 tuberculosis in animals not only by tubercular material 

 from the human subject, but also by portions of what were 

 known as the perlsucht nodules in cattle, and came to the 



