LOGARITHMIC ORDER OF DEATH 



45 



was shown by Eeichenbach (1911) with a culture of Bac- 

 terium paratyphosum exposed to heat (see Fig. 9; since 

 the temperatures used by this author were not exactly 

 alike in the different experiments, the data have been 

 made comparable by recalculation to a standard scale 

 where 99.9% of the inoculum are killed in 100 time units.) 



2 



60 TIM E. UNITS . 

 — 1, ■ — ^ •- 



Fig. 9. Semi-logarithmic plot of survivor curves of a culture of 

 Bacterium paratyiihosmn exposed to heat at different time intervals 

 after inoculation. Abscissa: time of exposure. (From data of Reich- 

 enbach, 1911.) 



The observation that young cells are more sensitive 

 than old ones is readily accepted by biologists because it 

 agrees with analogous findings with higher plants and 

 animals. Even in higher organisms, however, certain ex- 

 ceptions must be acknowledged, for instance, the greater 

 resistance of children against certain diseases. It is in- 

 teresting that similar exceptions have been observed by 

 Hoffmann (unpublished) with bacteria. Gentian violet 

 iias a much stronger effect on old bacteria than on young 

 ones. 



