7o8 



Tuberculosis 



and immediately dropped upon the surface of appropriate culture- 

 media in appropriate tubes; The fragments of tissue from the 

 spleen of the tuberculous guinea-pig are not crushed or comminuted, 

 but are simply laid upon the undisturbed surface of the culture 

 medium and then incubated for several weeks. If no growth is 

 apparent after this period, the bit of tissue is stirred about a little and 

 the tube returned to the incubator, where growth almost immediately 

 begins from bacilli scattered over the surface as the bit of tissue was 

 moved. As the appropriate medium, blood-serum was recom- 

 mended by Koch; glycerin agar-agar, 

 by Roux and Nocard; glycerinized po- 

 tato, by Nocard; coagulated dogs' 

 blood-serum, by Smith, or coagulated 

 Egg; by Dorset, may be mentioned. 

 The most certain results seem to follow 

 the employment of the dogs' serum and 

 egg media. 



Cultivatio n. — Blood-serum.— Koch. 

 first achieved artificial cultivation of the 

 tubercle bacillus upon blood-serum, 

 upon which the bacilli are first ap- 

 parent to the naked eye in about two 

 weeks, in the form of small, dry, 

 whitish flakes, not unlike fragments 

 of chalk. These slowly increase in size 

 at the edges, and gradually form small 

 scale-like masses, which under the 

 microscope are found to consist of 

 tangled masses of bacilli, many of 

 which are in a condition of involution. 

 The medium is so ill adapted to the 

 Fig. 279.— Bacillus tuberculosis requirements of the tubercle bacillus 

 on "glycerin agar-agar." ^^^ ^^^^ ^^^^ uncertain results that it 



is no longer used. 

 Glycerin Agar-agar. — In 1887 Nocard and Roux* gave a great 

 impetus to investigations upon tuberculosis by the discovery that 

 the addition of from 4 to 8 per cent, of glycerin to bouillon and agar- 

 agar made them suitable for the development of the bacillus, and 

 that a much more luxuriant development could be obtained upon 

 such media than upon blood-serum. The growth upon "glycerin 

 agar-agar" resembles that upon blood-serum. A critical study of 

 the relationship of massive development and glycerin was made 

 by Kimla, Ppupe, and Vesley,t who found that the most luxuriant 

 growth occurred when the culture-media contained from 5 to 7 per 

 cent, of glycerin. 



* ";Ann. de I'lnst. Pasteur," 1887, No. i. 



t "Revue de la Tuberculose," 1898, vi, p. 25. 



