VIII. 



TUBERCULOSIS 



LAENNEC (1791-1826), the inventor of the stetho- 

 scope, may also be called the founder of our present 

 knowledge of tuberculosis as a separate disease of 

 itself. Before his time, it had mostly been regarded 

 as a " degeneration " ; though its infective nature 

 had not gone without some recognition. 



Klencke, in 1843, showed that it was communi- 

 cable to animals by inoculation. Villemin, in 

 1865-68, showed its transmissibility from animal 

 to animal, and the identity of phthisis (tuberculosis 

 of the lungs) with those tuberculous affections of 

 the skin and of the joints which used to be called 

 scrofulous.* Chauveau, in 1868, showed that the 



" Villemin, by carefully conceived and conducted experi- 

 ments on animals, showed that tuberculosis was an infective 

 disease, due to a specific virus of a parasitic nature, which 

 was introduced from without. He showed that the virus 

 was capable of multiplying indefinitely in the bodies of 

 animals, and of being handed on from one animal to another 

 by inoculation. He also demonstrated by experiments on 

 animals the causal unity of the numerous manifestations of 



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