MECHANISM OF DEATH 



287 



tain quite a large number of reacting molecules. The 

 logarithmic survivor curves for higher organisms are 

 distinctly bulging as may be seen from Fig. 33 repre- 

 senting the death of wheat and mustard seeds. 



We have seen (p. 280) that for bacteria, the death rate 



1 log a — log h 



K = 



0.434 



remains constant. This K value must be constant when death is 

 brought about by the reaction of one molecule per cell. If the 



Fig. 33, — Order of death of seeds on standard scale. Wheat seeds, killed by 

 heat, and mustard seeds, killed by bichloride of mercury. 



number of ''reacting molecules" is larger than one, K increases. 

 When we compare the death rates of higher organisms with those 

 of bacteria, as shown in Table 80, it becomes conspicuous that 

 there is a continuous increase with all examples of the higher animals 

 and plants while with bacteria, the rate is either constant or 

 decreasing. 



All living beings except unicellular organisms show survivor 

 curves bulging out above the straight Une, indicating more than one 

 reacting molecule per cell (see e.g. Fig. 33). All bacteria (with three 

 exceptions to be discussed later) show either a straight line or a 

 survivor curve sagging below the straight line (see Figs. 31 and 34). 



