CHAPTER V. 

 TUBERCULOSIS. 



The baciUus of tuberculosis : discovery and morphology of the organism 

 — Growth on artificial media — Bacteriological diagnosis — Staining of 

 the bacilli in sputum and in sections — Pastor's cultivation method — 

 Number of bacilli in sputum — Occurrence and distribution of tubercu- 

 losis — Eesistanoe of the bacilli to desiccation — Pathogenesis — Special 

 regulations in force in New York and Germany — Koch's tuberculin 

 treatment of consumption — Preparation of tuberculin — Practical 

 disinfection. 



The discovery of the BaciUus tuberculosis was first announced 

 by Koch in 1882, though it had been shown in 1865 by 

 Villemin, and in 1877 by Cohnheim, that on inoculation 

 with tubercular sputum, guinea-pigs died from general 

 tuberculosis. 



The bacillus of tubercle is a slender rod, varying from 

 2" 5 to 4'0 fi long, and about 0'2 fj, thick ; the bacillus 

 is non-motile, it grows at blood-heat, and only on special 

 media, its growth even on these being very slow. On re- 

 peated subculture the organism becomes longer and thicker, 

 and as it develops a saprophytic habit, its virulence becomes 

 reduced, but may be restored on passing through an animal. 



The thermal death-point of the organism is 70° C. ; that 

 of the spores is higher, and appears to vary, not only with 

 the particular races, but also with the condition of damp- 

 ness or desiccation. Dried sputum has resisted boiling at 

 100° C. for over three hours. The growth of the organism 



