422 MICRO-OHaANISMS IN WATER 



TUBERCLE BACILLUS 



( Bacillus tnberc/iiiosiH ) 



Authority. — ^Koch, 'Die Aetiologie der Tuberkulose,' Mittheilungen a, d. 

 kaiserlichen Gesundheitsamte, vol. ii., 1884. 



"Where Found. — In all tuberculous diseases of man and animals. Found in 

 ditch-water by Fernandez, ' Infeccion tuberculosa por el agua contaminada,' 

 Bevista de Medicina e Cirnrgia praiica, 1890. 



Microscopic Appearance.— Very slender bacilli from 1-6 to 3*5 ^ long. When 

 stained -with methylene blue they look thinner than when gentian violet or 

 fuchsin is used. It is not motile. Spore formation is doubtful. (Fraenkel, 

 Grmidriss d. Bakterienkunde, 3rd edition, 1890, p. 380. Giinther, Einfilh/rung 

 in das Studium der Bahteriologie, 3rd edition, 189B, p. 221.) Stains with 

 difficulty ; Ziehl's carbol-fuchsin solution (p. 46) or Ehrlich's aniline water 

 fuchsin solution (p. 45) may be employed. An ordinary cover-glass prepara- 

 tion, fixed by heating in the usual manner, should be placed in a small watcb- 

 glass containing the fuchsin solution, which is heated over a Bunsen flame 

 until bubbles appear ; the cover-glass is then removed, and placed preparation- 

 side upwards in alcohol containing 3 per cent, of hydrochloric acid for one minute ; 

 it is then thoroughly washed and stained with a few drops of an aqueous 

 alcoholic methylene blue solution ; it is then washed and dried and passed again 

 three times through the flame in the usual manner (Giinther, loc. cit., p. 222), 

 The bacilli are stained by Gram's method. 



Cultures.— 



Gelatine. — No growth. 



Glyceeine-agab. — Grows abundantly, producing compact irregular growths 

 dirty white in colour and folded and wrinkled on the surface. (Nocard and 

 Kous add 6 to 8 per cent, of glycerine to ordinary nutritive agar-agar.) 



Blood Serum,— Forms a very thin grey white expansion. No liquefaction 

 ensues. "With an addition of glycerine to the serum the growth is very vigorous, 

 and a thick projecting faint white, mammellated expansion is produced (Nocard 

 and Roux, Annales de VInstihtt Pasteur, vol. i., 1887, p. 22). (See p. 19.) 



Potatoes.— At 37° C. in from 12 to 20 days smooth whitish colonies appear on 

 the potato, but the latter must be rendered alkaline and preserved in air-tight 

 tubes. (Pawlowski.) 



Glycerine Broth. — In veal broth plus 5 per cent, of glycerine small 

 riocculent particles collect at the bottom of the tube, which at the end of three 

 weeks have become very numerous (Nocard and Roux). It will also grow in 

 beef and other broth. 



Remarks. — This bacillus will neither grow below 29° C. nor at 42° C. The most 

 favourable temperature lies between 37° and 38° C. In artificial cultures it retains 

 almost its full complement of virulence even at the end of nine years of uninterrupted 

 tube cultivation (Koch, Tenth International Medical Congress, Berlin, 1890, vol. i. 

 p. 39), It is pathogenic to guinea-pigs, field-mice, rabbits and cats, but not to dogs^ 

 rats and white mice. For the effect produced by insolation on this bacillus see p. 354. 



