1950] 



GROWTH AND VARIATION OF BRUCELLA ABORTUS 



295 



of viable smooth organisms and enhanced the earlier and more rapid establish- 

 ment of nonsmooth variants. The curves of increase in viable cells of cultures 



12 3 



5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 

 DAYS 

 Figure 2. Growth (viable cell counts) of smooth B. abortus in synthetic medium supple- 

 mented with filtrates from old cultures. 



4 x 10° 



> 

 IxlO 7 



3x10' 



10 II 



13 



12 3 4 5 6 7 8 



DAYS 



Figure 8. Growth (viable cell counts) of smooth B. abortus in the presence of different 

 concentrations of DL-alanine. 



to which alanine had been added were strikingly similar to those of cultures to 

 which filtrates had been added (figures 2 and 3). 



In order to determine a possible differential resistance of smooth and rough 



137 



