MECHANISM OF DEATH 



339 



(6) THE ORDER OF DEATH 



The logarithmic order of death is the most common 

 form in chemical poisoning of bacteria if the disinfectant 

 is removed at the end of the experiment. The table 

 below shows the action of phenol upon the spores of B. 

 anthracis as determined by Chick (1908). 



Table 103. — Death of Spores of B. anthracis in 5% Phenol at 



20.2°C. 



A second example shows the very slow death of Bad. 

 typhosum in buffer solutions of different pH, according to 

 Cohen (1922). 



At pH 5 and 6.4 where the death rate is very low, it decreases 

 while it is quite constant at pH 7.1 and 8.7. This might be expected 

 if the decrease of the death rate is explained by variation in resistance. 

 In very weak disinfectants, the exceedingly slow rate of death gives 

 the most resistant bacteria a better chance to work against the 

 destructive agent. 



The logarithmic order requires a special justification 

 here because two components are reacting with each 

 other, namely, the bacterial cells (or some essential 

 part of their protoplasm) and the poison. A logarithmic 



