TUBERCULOSIS. 305 



incubator, where growth almost immediately begins from 

 the bacilli, which have been scattered over the surface as 

 the bit of tissue was moved about. 



Smith secures the tubercle bacillus from sputum by 

 intraperitoneal inoculation of a guinea-pig, and prefers 

 metastatic tuberculous foci to local foci of disease from 

 which to secure material for inoculation. The guinea-pig 

 should not be allowed to die, but should be chloroformed 

 at the end of the third week. 



The special tubes recommended by Smith are not 

 essential, as Ravenel, working in the laboratory of the 

 Pennsylvania State Live Stock Sanatory Board, has 

 successfully achieved the cultivation of the bacilli in 

 cotton-stoppered tubes sealed with paraffin. 



Kitasato has published a method by which Koch has 

 been able to secure the tubercle bacillus in pure culture 

 from sputum. After carefully cleansing the mouth the 

 patient is allowed to expectorate into a sterile Petri dish. 

 By this method the contaminating bacteria from the 

 mouth and the receptacle are excluded, and the expecto- 

 rated material is made to contain only such bacteria as 

 were present in the lungs. The material is carefully 

 washed a great many times in renewed distilled sterile 

 water until all bacteria not enclosed in the muco-purulent 

 material are removed ; it is then carefully opened with 

 sterile instruments, and the culture-medium — glycerin 

 agar-agar or blood-serum — is inoculated from the centre. 

 Kitasato has been able by this method to demonstrate 

 that many of the bacilli ordinarily present in tuber- 

 cular sputum are dead, although they continue to stain 

 well. 



Kitasato' s method of washing the sputum has been 

 modified and simplified by Czaplewski and Hensel. 1 In 

 their studies of whooping-cough, instead of washing the 

 flakes in water in dishes, they shook them in peptone 

 water in test-tubes. The shaking in the test-tube being 

 so much more thorough than the washing in dishes, fewer 



1 Centralbl. f, Bakt. u. Parasitenk., xxii., Nos. 22 and 23, p. 643. 

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