II. DISTRIBUTION OF B. COLI COMMUNE 
A. HIGHLY POLLUTED WATERS 
The highly polluted waters examined included several examples of crude 
sewage and of septic tank liquors, as well as of effluents from various sewage disposal 
works. In all these cases the bacillus was present in very large numbers, though 
filtration, if properly applied, seems to lessen the number very much. 
The sewage at West Derby contained B. coli to the extent of 52,000 per c.c. 
on one occasion, and of 27,470 on another (see Table III). The sewage of Manchester 
showed a distinctly lower figure, 5,000 per c.c. being the mean of 5 determinations, 
while that of Leeds gave 19,700 as the mean of 6 determinations. 
At Manchester the number of B. coli in the sewage was compared with 
the number in the septic tank liquors, both of the open septic tanks and of the 
Cameron. It was found that no increase took place, rather that there was a decrease. 
It must be noted, however, that the sewage had a distinct tarry odour, and probably 
contained many substances with antiseptic properties. The same thing was noticed in 
the case of the sewage and septic tank liquor at Leeds. Whether such a diminution 
would also take place in cases where the sewage is purely domestic is an interesting 
point. So far it would seem that the influence of the septic tank in sewage disposal 
was beneficial in reducing the numbers of B. coli. 
The B. coli in sewage or in septic tank liquors can largely be removed by 
filtration. In the Dibdin system it is by no means eliminated (see Table III) ; the 
effluent from the experimental Dibdin beds at West Derby showed nearly 10,000 
B. coli per c.c. A second filtration, which was continuous, improved the character of 
this effluent very much ; the numbers decreased to 239 per c.c. when a small experi- 
mental sand filter was used, and to 89 per c.c. when earth was used as the filtering 
material. This latter figure was the average of 18 determinations, and often B. coli 
was absent altogether, the diminution depending largely on the rate of flow. This 
result is confirmed by the fact that a very small number of B. coli per c.c. was found 
in the effluents from the land drains of the West Derby Sewage Farm. Here the 
average from 7 different drains on January 22nd was only 50 B. coli per c.c. 
Under the head of polluted waters one can consider rivers which receive much 
untreated sewage. The River Severn, at Shrewsbury, showed an average of 55 B. coli 
per c.c. on one occasion when the river was in flood ; on a second occasion the 
average number per c.c. was 180. The River Alt, which is contaminated by sewage, 
B 
