SEA-FISHERIES LABORATORY. 351 



this microbe decreased, showing that crude sewage was 

 an unfavourable medium for its development. In the 

 second experiment it remained alive for ten days, but 

 was not discoverable afterwards. 



Stajihylococcus pyogenes aureus, a pathogenic microbe 

 occasionally present in raw sewage, was then experimented 

 with. It was found that this organism could persist in crude 

 sewage for at least thirty-eight days. After that time it 

 was no longer recognisable. 



Houston's conclusions from these experiments is that 

 the pathogenic bacteria dealt with are capable of retaining 

 their vitality in crude sewage for a considerable time. 

 But he also points out " that the number of the pathogenic 

 germs added to the sewage in these experiments was vastly 

 greater that could conceivably take place under natural 

 conditions, and that, notwithstanding the enormous 

 numbers introduced, there was definite indication of a 

 somewhat rapid decrease in their numbers." [Ibid. p. 75.) 



(2) MacConkey (Report Eoyal Commission on Sewage 

 Disposal, 2 (cd.1178), 1902) determined the longevity of 

 Bacillus typhosus in various sewage liquids, and found 

 that this microbe did not find a suitable habitat in any of 

 the liquids dealt with. Crude sewage was inoculated with 

 the typhoid bacillus, and it was found that it died out 

 rapidly. In one experiment it disappeared six days after 

 the date of inoculation, and in another was not recognised 

 after the lapse of thirteen days. Effluents from various 

 septic purification processes were also employed, and it 

 was found that these were even more inimical to the life 

 of the bacillus than crude sewage. A portion of Cameron 

 bed effluent (such as we have to deal with at Morecambe) 

 was inoculated with typhoid bacilli to the extent of twelve 

 millions per cc, and at the end of seven days the number 

 of the bacilli had decreased to 200 per cc. MacConkey's 



