CULTIVATION OF THE BACILLUS 85 



animals, and this they did on media containing the dead 

 bodies of acid-fast bacilli, glycerine extracts of such 

 bacilli, or the products of their growth. These authors 

 prefer an agar or a serum-agar foundation for their 

 media as being less troublesome to prepare than 

 egg media. They were unable to obtain growth on 

 any of the ordinary media, but they obtained good 

 growths on liquid media made up of two parts of 

 ordinary broth containing 5 per cent, glycerine, and 

 one part of a 5 per cent, glycerine-broth culture 

 of the B. phlei that had been steamed for two hours, 

 and then centrifuged to remove the bacilli. Their 

 cultures on various media are illustrated by excellent 

 photographs in the Journal of Comparative Pathology^ 

 September, 1912. 



Regarding the use of a glycerine extract of the 

 tubercle bacillus for making media, the authors state : 



" As previously stated, at the outset we used 

 the egg medium first recommended by Twort and 

 Ingram, and nearly always with success. It is, 

 however, a medium with some notable defects. 

 In the first place it is a little troublesome to pre- 

 pare, especially when perfectly fresh eggs are not 

 available. Secondly, it is an opaque medium, and 

 therefore does not allow one to observe the appear- 

 ance of any growth on it by transmitted light. On 

 this account peculiarities of growth are apt to be 

 overlooked, and accidental impurities are not so 

 easily detected as on a transparent or translucent 

 medium. Finally, the abundant presence of tuber- 

 cle bacilli in the substance of the medium is very 

 objectionable when in doubtful cases one wishes 

 to determine by microscopic examination whether 

 any multiplication of the implanted Johne's bacilli 

 has taken place. 



