BACTERIA DEVELOPING AT DIFFERENT TEMPERATURES 241 



while the fluctuation in the numbers of total bacteria, of bacteria 

 growing at 40, and of B. coli, was less in the Applied 216 than in 

 the canal, the fluctuation in the ratios between these numbers was 

 very much greater. 



Comparing the canal with Applied 219, we find that by adding 

 a small proportion of sewage to the water we have increased our bac- 

 terial content, as shown by higher values on all three determinations ; 



TABLE 8. 



APPLIED 216: AVERAGE MONTHLY NUMBERS OF BACTERIA AT 20 C., AT 40 C., AND of B. coli, AND 



THE BACTERIAL RATIOS. 



but by comparing our ratios we find that we have increased the class 

 of bacteria developing at 40, in which must be included the disease 

 germs in a much larger proportion than we have increased the total 

 bacterial content. The fluctuation in the numbers of the different 

 classes of bacteria and the fluctuation in the ratios between these 



TABLE 9. 



APPLIED 219: AVERAGE MONTHLY NUMBERS OF BACTERIA AT 20 C., AT 40 C., AND OF B. coli, AND 



THE BACTERIAL RATIOS. 



