MECHANISM OF DEATH 



289 



that of Schultz and Ritz (1910). Similar results were 

 obtained independently by Sherman and Albus (1923) 

 who tested Bad. coli in its resistance to heat, to cold, to 

 salt solutions, and to phenol. Some of their results are 

 summarized in the following table. 



Table 81. — Death of Cells from Young and Old Cultures op 



Bad. coli 



The differences in the percentage and in the death rate 

 of survivors are so striking and check so well with the 

 preceding experiment that a ''physiological youth" 

 of bacteria, as the latter authors termed it, must be 

 considered established. It seems proved that the 

 physiologically young bacteria are more sensitive to 

 adverse conditions than old ones. This circumstance 

 is probably one of the main reasons for decreasing death 

 rates and sagging survivor curves. 



