Multiple Mechanisms of Drug Resistance 155 

 C 



Fig. 7. Induction to proflavine resistance by 1 • 5 

 {xg./ml. and 5 pig. /ml. proflavine in non-dividing 

 suspensions of Esch. coli Rg. Changes in numbers 

 of sensitive cells, and of cells resistant to different 

 concentrations of proflavine, at different times 

 during 14 days incubation at 37°C. 



A — control, no proflavine in suspension 



B — induced by 1 -5 jxg./ml. proflavine 



C — induced by 5 {xg./ml. proflavine 



1 — total viable count 



2 — count of cells resistant to 20 (i,g. /ml. proflavine 



3 — count of cells resistant to 50 [jLg./ml. proflavine 



4 — count of cells resistant to 100 [xg./ml. proflavine 



5 — count of cells resistant to 200 (jt.g./ml. proflavine 



Time from beginning of incubation of the induc- 

 tion suspension. 



