724 



Tuberculosis 



tubercle bacillus upon an egg medium, which has the advan- 

 tage of being cheap and easily pre- 

 pared, while eggs are always at hand, 

 and can be made into an appropriate 

 medium in an hour or two. He also 

 claims that the chemic composition 

 of the eggs makes them particularly 

 adapted for the purpose. The me- 

 dium is prepared by carefully open- 

 ing the egg and dropping its contents 

 into a wide-mouth sterile receptacle. 

 The yolk is broken with a sterile 

 wire and thoroughly mixed with the 

 white by gentle shaking. The mix- 

 ture is then poured into sterile tubes, 

 about 10 c.c. in each, inclined in a 

 blood-serum sterilizer, and sterilized 

 and coagulated at 70 C. for two 

 days, the temperature being main- 

 tained for four or five hours each 

 day. The medium appears yellow- 

 ish and is usually dry, so that before 

 using it is well to use a few drops of 

 water to make conditions appropri- 

 ate for the growth of the tubercle 

 bacillus. 



Potato. Pawlowski* was able to 

 isolate the bacillus upon potato. 

 Sander found that it could be 

 readily grown upon various vege- 

 table compounds, especially upon 

 acid potato mixed with glycerin. 

 Rosenauf has shown that it can 

 grow upon almost any cooked and 

 glycerinized vegetable tissue. Ac- 

 cording to French writers, the viru- 

 lence of the bacillus is not dimin- 

 ished when it grows upon potato. 

 It has also been said that the con- 

 tinued cultivation of the tubercle 

 bacillus upon culture-media lessens 



Fig. 241. Bacillus tu- 

 berculosis; glycerin agar- 

 agar culture, several 

 months old (Curtis). 



' ''Ann. de 1'Inst. Pasteur," 1888, t. vi. 

 t " Jour. Amer. Med. Assoc.," 1902. 



