90 



THE GROWTH AND DEATH OF BACTERIA 



TABLE 3 



Growth of Salm. typhi-murium in Broth (Wilson 1922) 



Instead of plotting the logarithms of the bacterial numbers against time. Lemon (1933) 

 has pointed out that interesting information may be obtained by estimating the actual 

 rate of growth in unit intervals of time. 



If for each period of time T the count is Nq, N^, Nj . . . etc. at times t^, t^, t^ . . . t 

 the following formula may be used : 



(Ni - No) 

 ih - ^o)i(T,) 



and 



(Na - Ni) 



(<2 - ^i) 



and 



(N3 - N2) 



J(T,-T,)+T. 



(h - h) 



etc. 



KT,-T,) + T, 



150. 200 250 300. 



TIME IN MINOTES 



Fig. 16. — Growth of Salm. typhi-murium in Broth, plotted according 

 TO Lemon's Formula. 

 Continuous line = Numbers plotted logarithmically against time. 

 Interrupted line = Rate of arithmetic increase plotted against time. 



