CHAPTER V. 



TUBERCULOSIS. 



The bacillus 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 baciUi in sputum — Occurrence and distribution of tuber- 

 culosis — Infection by air, dust, meat, milk, etc. — Evidence given 

 before Eoyal Commission on Tuberculosis — Eesistanoe of the bacilli 

 to desiccation — Pathogenesis — Special regulations in force in New 

 York and Germany — Presence of tubercle bacilli in air of hospital 

 wards, etc. — Identity of human, avian and bovine tubercle baciUi — 

 Bang's method for eliminating tuberculosis from cattle — Koch's 

 tuberouhn treatment of consumption — Preparation of tuberculin — 

 Practical disinfection. 



The discovery of the ^aciZ^Ms tubercalosisy^asHist 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 02 a 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 



