74 



SEWAGE AND ITS PURIFICATION 



as possible on the spot, and the following tables, giving the 

 maximum and minimum results obtained, show the frequency 

 of certain organisms in the various effluents : 



Total organisms (gela- 

 tine 20° C.) 



B.coli ... 



Spores of B. enteritidis 

 sporogenes 



Organisms per c.c. 



Raw 

 Sewage. 



Septic 

 Effluent. 



Primary 

 Effluent. 



Secondary 

 Effluent. 



Tertiary 

 Effluent. 



23 millions 2| to 4 4^ millions i to 2 10,000 to 



! millions ' millions 700,000 



I to 10 ] 100,000 to 100,000 I 10,000 to I 1,000 to 



millions ! i million j j i million 1 10,000 



100 toi.ooo'iooto 1,000' 20 to 100 10 to 100 10 to 100 



The London County Council Report of 1899 describes some 

 new species in London crude sewage which, after comparison 

 with all others of their class, appear distinct. 



B. mesentericiis, two varieties, I and E (Figs. 10 and 11, 

 Plate IV.). Variety I rapidly liquefies gelatine and blood- 

 serum, apparently peptonizes milk without subsequent coagula- 

 tion, and has no reducing action on nitrates. Variety E is 

 longer, liquefies gelatine very slowly, liquefies blood-serum 

 fairly rapidly at 37° C, and produces a weak clot in milk which 

 appears to subsequently redissolve. It reduces nitrate to nitrite 

 in twenty-four hours at 37° C. From ten to thirty spores per 

 c.c. exist in London sewage. 



Sewage proteus, differing from Proteus vulgaris, mirahilis, and 

 zenkeri, liquefies gelatine and serum* and peptonizes milk 

 without coagulation. It was present in great numbers (usually 

 over 100,000 per c c.) in both crude sewage and effluents, and 

 is suspected to be pathogenic, judging from some experiments 

 on guinea-pigs (Figs. 4, 5, and 6, Plates I. and II.). 



B. frondosus, SL, a large bacillus, giving a leafy appearance 

 at the edge of the colonies. 



B. fusiforniis, NL, with spindle-shaped spores and somewhat 

 negative culture characters, seems to be a new species (Fig. 9, 

 Plate III.). 



B, suhtilissimus, NL, resembles a large micrococcus (Fig. 12, 

 Plate IV.). 



B. suhtilis, L. Several varieties occur in sewage. Two — 

 A and B — are specially described in the report. 



B, membraneus patulus, SL, a very large species, which forms 

 long chains (Fig. 8, Plate III.). 



