Distribution 711 



Specific Organism. Although the acute men of the early 

 days of pathology clearly saw that the time must come 

 when the parasitic nature of tuberculosis would be proved, 

 and Klebs, Villemin, and Cohnheim were " within an ace " 

 of its discovery, and Baumgarten* probably saw it in tissues 

 cleared with lye, it remained for Robert Koch to demon- 

 strate and isolate the Bacillus tuberculosis, the specific 

 cause of the disease, and to write so accurate a description 

 of the organism, and the lesions it produces, as to be almost 

 without a parallel in medical literature. 



Distribution. So far as is known, the tubercle bacillus is 

 a purely parasitic organism. It has never been found 



,* r '.<Fm 



*fr /-Jfjtu $/ W, 



>:'*( \ .'% -; f /'/ ; %- 



"/'^A'^^^' 



&-'& $ #>*'./.; 



Fig. 236. Tubercle bacillus in sputum (Frankel and Pfeiffer). 



except in the bodies and discharges of animals affected with 

 tuberculosis, and in dusts of which these are component 

 parts. This purely parasitic nature interferes with the 

 isolation of the organism, which cannot be grown upon 

 the ordinary culture-media. 



The widespread distribution of tuberculosis at one time 

 suggested that tubercle bacilli were ubiquitous in the at- 

 mosphere, that we all inhaled them, and that it was only 

 our vital resistance that prevented us all from becoming its 

 victims. Cornet, f however, showed the bacilli to be present 



* "Virchow's Archives," Bd. LXXXII, p. 397. 



t "Zeitschrift fur Hygiene," v, 1888, pp. 191-331. 



