LOGARITHMIC ORDER OF DEATH 



55 



This equation could be used, in the following form, to 

 determine the death rate : 



K = 



log m 



That the amount of contamination influences very defi- 

 nitely the time required for sterilization, is an every-day 

 experience in the dairy industry, in the canning indus- 

 try and in surgery. Quantitative data, given by Esty and 

 Myers (1922) on spores of Clostridium botuJinum, are 

 reproduced in Table 9. Sometimes K is not constant, 



TABLE 9 

 Time required to sterilize by heat cultures of different concentra- 

 tions of spores of Clostridium botulinum. (From Esty and Meyer 

 1922.) ' 



but decreases as the cell concentration increases. This 

 is attributable to the protective effect of large numbers of 

 dead cells (see p. 59). The second half of Table 9 shows 

 this effect when the number of spores is nearly 100 times 

 as large as that employed in the upper half. 



The outstanding fact that an increase in infection in- 

 creases the death time is contrary to any explanation of 

 the order of death by various degrees of resistance. Cells 

 of very high resistance are rare and a large quantity of 

 bacteria may contain a few extremely resistant cells 

 which are not usually encountered in small quantities. 



