Bacteria Developing at Different Temperatures 237 



intermittent sewage filters, and practically absent from the fourth, 

 while they were present in greater or less numbers in the sewages 

 and in the effluents from the contact and trickling filters through 

 which the sewage passed more rapidly. The presence of such small 

 numbers of this type of bacteria in the polluted river water, and 

 of similar numbers in the effluents from the primary water filters, 

 cannot be accounted for at the present time. 



table No. 4. 



Average Number of Bacteria and Acid -Producers Developing at 20°, 40°, and 50° C. with 



Different Classes of Waters. 



Regular sewage 



Station .sewage 



Septic sewage 



Sand Filter No. i 



"2 



4 



"9 



Trickling Filter No. 13s 



" " 136 



Contact Filter No. 175. 



" 176. 



" 251. 



Canal 



Intake 



Applied 216 



Filter No. 8 



Filter No. 216 



Filter No. 243 



City filter 



C'ity water 



Pond No. I 



Pond No. 2 



Driven wells 



Shallow Well No. i 



Shallow Well No. 2 



Spring No. i 



Spring No. 2 



Bacteria per c.c. 



20° C. 

 4D. 



,900,000 



,676,000 



485,000 



1.640 



35 



1.300 



670 



15.500 



23,300 



146.600 



380,000 



306,000 



16,400 



16,900 



2,8oo 



32 

 7IS 



62 

 150 



64 



27 

 71 

 41 



1,000 



S07 



49 

 80 



40" C. 

 24 Hr. 



So°C. 

 24 Hr. 



Acid-Producing Bacteria 



20" C. 

 4D. 



1,940.000 



1,032,000 



241,000 



2,360 



29 



345 



1,045 



15,200 



16,000 



112,400 



292,000 



193,000 



6,700 



2,500 



1,650 



6 



259 



16 



14 

 II 



8 

 30 



o 



3 



82 



6 



8 



40° C. 

 24 Hr. 



346,000 



283,000 



90,000 



1. 195 



2 



119 



154 



1.360 



1,180 



22,700 



45.000 



46,000 



87 



134 



66 



I 



101 



o 



17 



3 



I 



S 

 o 

 I 

 55 

 o 

 2 



So'C. 

 24 Hr. 



4.400 



24,900 



240 



I 



o 



o 



o 



100 



20 



8,000 



8.000 



200 



2 

 2 

 I 

 I 

 1 

 O 

 I 



o 

 o 

 o 

 o 

 o 

 o 

 o 



Bacterial ratios, jo° series. — The bacterial ratios for the ditTercnt 

 waters included in the 50° series are shown in Table 5. In general 

 the 20°-40° bacteria ratios and the ratios between the 20° bacteria 

 and the 40° acid-producers were much greater for the sewage and 

 the effluents from sewage filters than for the other waters, although 

 there are a few exceptions to this rule. The 20°-40° ratios for the 

 polluted river water in each case were much less than the correspond- 

 ing ratios for Applied 216 and for the effluents from Water niters 

 No. 8, 2x6, and the City Filter, indicating that the removal of the 



