BACTERIA OCCURRING IN SEWAGE 93 



[that land effluents are usually less pathogenic than those from 



bacteria beds is very inadequately supported by his one fatal 



[result on injection of an effluent from a single bacterial process 

 Report, p. 49). In the only other case quoted, from a different 

 )acterial process, the animal . recovered. Crude sewages and 

 iffluents, which had been heated to 100° C. for one hour, or 

 >assed through a Pasteur filter, did not produce any injurious 



jffect, even in large doses. It would follow that the ptomaines, 

 ^hich have sometimes been suggested as a danger of bacterial 



processes, are not of significance. 



In the same Report, Dr. MacConkey {" Longevity of 



B. typhosus in Sewage and Sewage Effluents," ibid., p. 62) sums 



up his results as follows : 



" We know that typhoid bacilli must find their way into the 

 sewage from the excreta of persons suffering from typhoid, but they 

 cannot be in large numbers, and in the various samples of crude 

 sewage which we have examined we have not found any. Therefore 

 it may be concluded that, allowing that these bacilli do reach 

 biological beds or septic tanks, they are present in such small 

 numbers, and the conditions are so adverse to their existence, that 

 they will not survive the treatment. But if from any cause they 

 arrived at the beds or tanks in such numbers as the B. coli, then 

 certainly they might appear in the effluent just as the B. coli does. 

 But as in the case of the latter bacillus, so also in the case of the 

 B. typhosus J there is no tendency to multiplication in the effluent." 



From some sewages and effluents Dr. Houston records his 

 isolation of B. pseudo-tuberculosis and B. pyocyaneus, " both 

 highly pathogenic to lower animals, and also related to morbid 

 processes occurring in the human subject" {ibid., p. 58). He 

 has discovered B. anthracis at Yeovil in sewage and some 

 effluents connected with hide factories {ibid., p. 31). In crude 

 sewage he finds B. coli and allied forms are apt to be at least 

 100,000, spores of B. enteritidis sporogenes at least 100, and 

 streptococci at least 1,000 per c.c. (p. 25). He urges the im- 

 portance of a streptococcus test (further explained at p. 144 of 

 the Report), and remarks (p. 29) that, although both bacteria-bed 

 and land processes can yield effluents seemingly non-putrescible, 

 these are not to be thought of as safe in the case of drinking- 

 streams. Chemical standards are always essential. A bacterial 

 standard is required for drinking-streams, and is of more im- 

 portance than the chemical one ; for non-drinking streams it is 

 useful as an adjunct to the chemical standard (ibid., p. 29). 



The effect of subsequent filtration on a biological effluent was 

 investigated by the Commission, and it was_concluded that 



