TUBERCULOSIS. LEPROSY 



87 



sular substance. The tubercle bacillus is non-motile, 

 and is supposed to produce no spores, although some 

 difference of opinion upon this point still exists. 



Staining and Culti- 

 vation. The tubercle 

 bacillus stains im- 

 perfectly or with great 

 difficulty, and when 

 once stained resists 

 all efforts to decol- 

 orize it with acids; 

 it is known with a 



few Other Organisms FIG. 17. Tubercle bacilH. 



as an "acid-proof bacillus." This characteristic re- 

 sistance to staining and decolorization constitutes one 

 of the chief means of identifying the organism. 



The cultivation of the tubercle bacillus upon arti- 

 ficial media is very slow and uncertain. Koch first 

 succeeded in cultivating it upon blood-serum, which 

 still remains the most satisfactory medium. When 

 cultures have been successfully grown it is less diffi- 

 cult to transfer them to other substances such as 

 potato, carrot, or macaroni. 



No growth is discernible before the end of ten days, 

 which probably accounts for the many failures of 

 early investigators. Cultures from the tissues show 



