MECHANISM OF DEATH 347 



If the X- values for two different concentrations are 

 known, we have 



The equation for the logarithmic order of death, which 



was 



K't = log5 



for any one concentration of a poison, is then changed to 



i^.^c- = log5 



when different concentrations are concerned. Applied 

 to the endpoint method where r^ and consequently 



log 7 is constant, we must find the relation 



log ^2 — log ^1 

 t ' c^ = constant, or tiCi" = ^2^2**, ovn = , — log c 



This computation of the concentration exponent is 

 made under the assumption that the poison combines 

 chemically with some molecules of the cell to a definite 



