LOGARITHMIC ORDER OF DEATH 



23 



causes the death of the organism varies from 1 to 500. 

 The calculation is carried out for survival rates of 10%, 

 20% and 30%. Table 4 shows the gradual decrease in 

 the number of survivors, for a survival rate of 50%. 

 In Table 6 the percentages of survivors are compared 

 when the death of n definite, or that of n random cells 

 kills the organism. 



Figure 4 gives the mortality curves and Fig. 5, the 

 survivor curves on semi-logarithmic scale, for various 

 values of n, and for a survival rate of 50%. When n = 

 1, the mortality curve as well as the survivor curve are 

 plainly those of bacteria. As n increases, the curves be- 

 come more and more similar to those characteristic of 

 higher organisms, and for n = 8 or more, they are prac- 

 tically identical with them. 



Thus, the two different orders do not involve dif- 

 ferences in the chemical dynamics of death; they are 

 merely different results of the same principle at dif- 

 ferent levels of organization. As death of one single 

 cell does not kill a large animal or plant, the organ- 

 ism survives until enough cells are inactivated to cause 



TABLE 4 

 Number of survivors in a population of 100 muIticeUular organ- 

 isms, calculated on the assumption that an individual dies when n of 

 its cells are inactivated, and that the death rate of the cells is 50% 

 per minute. 



