METHODS OF EXAMINATION 305 



medium, under strict aseptic precautions, with portions of a 

 tubercular organ, e.g., the spleen. The portions of tissue should 

 be fairly large, and should be well rubbed into the broken 

 surface of the medium. Cultures may, however, be obtained 

 from sputum by means of antiformin, as this substance readily 

 kills most of the ordinary bacteria and has comparatively slight 

 effect on the tubercle bacillus. Antiformin should be allowed to 

 act 011 sputum in the proportion and for the time mentioned in 

 paragraph (1), the mixture should then be centrifugalised, the 

 supernatant fluid removed, and the deposit washed with sterile 

 water and again centrifugalised, these processes being repeated 

 several times. If, then, inoculations be made from the deposit 

 on blood serum or on Dorset's egg medium and glycerin egg 

 medium, pure cultures of the tubercle bacillus may, in some 

 instances, be obtained. The method is one which gives good 

 results. Another somewhat similar method is that introduced 

 by Twort ; in this, portions of sputum are exposed to the action 

 of a 2 per cent, solution of ericolin (a glucoside) for an hour at 

 38 C., and thereafter cultures are made on Dorset's medium. 



(4) Reactive phenomena. The presence of immune-substances 

 in the blood and the tuberculin reaction, along with the methods 

 of applying the respective tests, have been described above 

 (p. 295). 



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