BACTERIA OCCURRING IN SEWAGE 73 



B. siibtilisy L. Forms highly resistant spores ; rapidly consumes 



oxygen. 

 B. sulphureiim, L. Liquefies casein ; produces HgS. 

 B. lactis cyanogenus, NL ; evythvosponis^ NL ; nibescens, NL ; pyo- 



cyaneus, L. (a culture from London sewage proved extremely 



virulent). 

 Several varieties of thermophiHc bacilli, capable of luxuriant growth 



at temperatures above 50° C, and producing spores. 

 Micrococcus (and Bacillus) uvea, NL ; urecs liqtiefaciens, L. Converting 



urea into ammonium carbonate. 

 M. tetragenus mobilis ventrictdi, NL. Reduces nitrates. 

 M. casei, NL. ; albicans ampins, L ; fervidosus, NL. 

 Streptococcus mirabilis, NL ; vermiformis, L; coli gracilis, L; liqtie- 

 faciens coli, L. 

 Spirillum plicatile, serpens, undula, tenue, and volutans. 

 Sarcina alba and lutea, SL. 



Proteus vulgaris, L. Produces NH3 from nitrogenous organic matter. 

 Proteus mivabihs, L; zeukeri, L; sulphureus, L. (produces NH3 and 



mercaptan). 

 Beggiatoa alba. Secretes granules of sulphur, formed, according to 



Winogradsky, by oxidation of H.^S, and finally turned into 



H2SO4 by the plant. 



Klein's B, enteritidis sporogenes is pathogenic to small animals, 

 and has been associated with infantile diarrhoea. As a type 

 of a pathogenic anaerobe invariably present in sewage, its 

 isolation acquires special importance. Tubes of recently 

 sterilized milk are inoculated with the diluted sewage and 

 heated to 80° C. for ten minutes, in order to eliminate all non- 

 sporulating bacteria. The milk cultures are then incubated 

 anaerobically at 38° C, either by placing the tubes over 

 alkaline pyrogallate, or excluding air from the surface of the 

 milk with a few c.c. of sterile vaseline. After some twenty 

 hours' incubation the cultures are examined for the '* enteri- 

 tidis reaction " — i.e., the milk is completely coagulated with 

 abundant gas production, the fluid is nearly clear, the small 

 dense clots are shattered by the gas, and often forced up 

 above the liquid, acquiring a slight pink tinge. The culture is 

 then examined microscopically, the absence of spores proved, 

 and conclusive inoculation tests may be made with guinea- 

 pigs. Other sewage organisms yielding the " enteritidis milk 

 reaction " are B. butyricus — produces spores in anaerobic milk 

 cultures at blood heat — and B. cadaveris sporogenes — requires 

 some forty-eight hours' incubation to coagulate the milk. 



The author has recently had occasion to make almost daily 

 bacteriological examinations at the Guildford Sewage Works 

 during the summer months. The tests were conducted as far 



