210 



NATURE OF ANTIBIOTIC ACTION 



struction of all the cells. The bactericidal action of actinomycin seems 

 to be a result of a chemical interaction, similar to that of other anti- 

 septics. On adding o.i mg. actinomycin to a suspension of E. coli cells 

 in a 10 ml. buffer solution, the value of the constant K was found to 

 vary from 0.02 1 to 0.026 for different periods of incubation. Figure 24 

 illustrates graphically the effect of different concentrations of actino- 

 mycin on the death rate of E. coli in buffer solution. 



12 18 24 30 36 



INCUBATION PERIOD IN HOURS 



Figure 24. Action of actinomycin on E. colt; death rate in buffer solution. 

 Amounts are given in milligrams of actinomycin per 10 milliliters of solu- 

 tion. From Waksman and Woodruff (948). 



