8o STUDY AND IDENTIFICATION OF BACTERIA 



rapidly than the other types (three to four days), and grows best at 24 

 C., growth ceasing at 36 C. The colonies are round and moist. 



It is certain that many of the symptoms usually noted in the tuberculous are due 

 to secondary infections. Pettit, by careful blood cultures, obtained the pneumo- 

 coccus in 24 cases and the streptococcus in 36 cases out of 130 cases studied. He 

 used from 5 to 20 c.c. of blood from the vein. Positive blood cultures were obtained 

 in 68% of far-advanced cases, 45% of advanced cases and 16% of incipient cases. 



The best culture medium for primary cultures is blood-serum or, 

 better, a mixture of yolk of egg and glycerine agar. Dorset's egg me- 

 dium is also used. In subcultures, either glycerine agar, glycerine 

 potato, or glycerine 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 glycerine 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 glycerine bouillon in the flask. 



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

 poison is assumed to be intracellular. 



Koch's old tuberculin, which was simply a concentrated glycerine bouillon 

 culture, is now principally used in veterinary diagnosis. It was prepared as follows: 



After four to six weeks the surface growth begins to sink to the bottom of the 

 flask. This fully developed culture is evaporated over a water bath at 80 C. to 

 one-tenth the original volume. It is then filtered, the final product containing 

 about 40% of glycerine. 



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 (T. O.) is discarded. Subsequent trituration and centrifugaliza- 

 tion, preserving each time the supernatant suspension, gives the new tuberculin. 

 It has been found at times to contain virulent T. B. 



Koch's bazillen emulsion has been more recently introduced by Koch (1901). 



This is simply a suspension of ground up bacilli in 20% glycerine solution. 

 Another preparation is the bouillon filtrate of Denys. This is the unheated filtrate 

 of broth cultures of human T. B. It contains 1/4% phenol. 



In the use of T. R. and of bazillen emulsion, Sir A. Wright recommends doses 

 of 1/4000 of a milligram, and he rarely goes beyond i/iooo of a milligram in treatment. 

 These products come in i c.c. bottles containing 5 mg. of bacillary material. It is 

 convenient to remove 2/10 of a c.c., containing i mg. Add this to 10 c.c. of glycerine 

 salt solution with 1/4% of lysol. Each c.c. contains i/io mg. One c.c. of this stock 



