36 BACILLUS TUBERCULOSIS 



rarely presents the typical beading or bending, but 

 usually stains in a homogeneous manner, and is found 

 lying in clumps, occasionally of considerable size, 

 and usually, as might be anticipated, associated 

 with the pus cells contained in the urine. In all 

 urine, but especially in the urine of women, the 

 bacillus may be confused with the Smegma Bacillus 

 (Fig. 35), which has a similar staining reaction, but is 

 said to lose its stain when treated with alcohol sooner 

 than the bacillus tuberculosis similarly treated. 



From tubercles and tubercular materials, the 

 specific bacillus was isolated and cultivated by 

 Koch. Using gelatinised sterile blood serum as the 

 cultivating medium, and spreading upon this surface 

 the well-crushed material from an uncontaminated 

 tubercle, faint traces of growth may be observed 

 spreading from the inoculated material after about 

 fourteen days' incubation at 37 C. The growth 

 subsequently increases slowly, and forms small dry, 

 scaly, raised, limpet-like crusts. The primary cul- 

 tures are difficult to obtain, and not copious ; but the 

 sub-cultures are less exigent and can be grown with 

 greater facility on other media, especially the agar 

 medium containing glycerine 6 per cent, and sugar 

 2 per cent., which was originally suggested by Nocard 

 and Koux. On this medium, unsuitable -though 



