TUBERCULINS. 69 



less spreading culture. There is also a fish tuberculosis. This 

 organism grows much more rapidly than the other types (3 to 4 days), 

 and grows best at 24 C., growth ceasing at 36 C. The colonies are 

 round and moist. 



The best culture media for primary cultures are blood-serum or, 

 better, a mixture of yolk of egg and glycerin agar. Dorset's egg 

 medium is also used. In subcultures, either glycerin agar, glycerin 

 potato or glycerin bouillon make good media. In inoculating media 

 from tuberculous material, as, say, from a tuberculous gland or, more 

 practically, from the spleen of a guinea-pig, the material must be 

 thoroughly disintegrated or rubbed on the surface of the media so 

 that individual bacilli may rest on the surface of the culture media. 

 In growing in flasks in glycerin bouillon a surface growth is desired. 

 The cylindrical flask of Koch gives a better support to the pellicle than 

 an Erlenmeyer one. In inoculating, a scale of such a surface growth 

 or a grain from the growth on a slant should be deposited on the 

 surface of the glycerin bouillon in the flask. 



Inasmuch as the filtrate from cultures has little toxic effect, the 

 poison is assumed to be intracellular. 



Koch's old tuberculin, which w r as simply a concentrated glycerin 

 bouillon culture killed by heat, is now principally used in veterinary 

 diagnosis. 



Koch's tuberculin "R" or new tuberculin was introduced in 1897. 

 In this, virulent bacilli are dried In vacuo, ground up in water and 

 centrifuged. The first supernatant fluid is put aside as tuberculin O. 

 Subsequent trituration and centrifugalization, preserving each time 

 the supernatent suspension, gives the new tuberculin. It has been 

 found at times to contain virulent T. B. 



Koch's bazillen emulsion has been recently introduced by Koch. 

 This is simply a suspension of ground-up bacilli in 50% glycerin solu- 

 tion. It contains both T. R. and T. O. 



In the use of T. R. and of bazillen emulsion, Sir A. Wright recom- 

 mends doses of 1/4000 of a milligram, and he rarely goes beyond 

 i/ 1000 of a milligram in treatment. These products come in i c.c. 

 bottles containing 10 mgs. of bacillary material. It is convenient to 

 remove i/io of a c.c., containing i mg. Add this to 10 c.c. of glycerin 



