86 LABORATORY BACTERIOLOGY 



EXERCISE XLI 



BACTERIUM (BACILLUS) OF TUBERCULOSIS 



132. The tubercle bacterium does not grow readily on the 

 ordinary media. For its cultivation blood serum, glycerin 

 agar, or bouillon containing 5 to 7% glycerin are ordinarily 

 used. Formerly it was with much difiSculty that it was made 

 to grow from lesions in tuberculous animals ; but when a culture 

 was once started it could, on the media mentioned above, and 

 sometimes on agar, be cultivated in subcultures with compara- 

 tive ease. More recently Dr. Theobald Smith has described 

 a method which renders its cultivation from tuberculous lesions 

 much easier. (For details, see Appendix IV.) It grows very 

 slowly and it is necessary that the temperature should be kept, 

 without variation, at about 37" C. On account of these diffi- 

 culties it is not practicable, in a general course, to cultivate this 

 organism, but cultures on solid and liquid media will be fur- 

 nished by the instructor for examination. It is important, 

 however, to be able to recognize this organism in tissues and 

 sputum, and consequently the following additional exercise in 

 staining and studying it is given. 



References. — Chapters on this organism in text books. Smith, 

 Jour, of Exp. Med., 1898, p. 451. Moore, Med. News, May 14, 1892 

 (methods of staining). Nuttall, Johns Hop. Hosp. Bulletin, 1891, 

 Vol. II., p. 67. Dorset, Report Am. Public Health Asso., XXIV., 

 p. 157. 



133. Work for this Exercise. — Examine and carefully de- 

 scribe the appearance of the cultures of the tubercle bacterium 

 on glycerin agar and in glycerin bouillon furnished. 



Make 2 cover-glass preparations from the culture furnished 

 for that purpose and stain them with carbol fuchsin (86) . 



Make 4 cover-glass preparations from tuberctilous sputum 

 and stain for tubercle bacteria. It is often desirable to counter 



