Bacillus coli communis. Surface gelatine plate culture, O'l c.c. ot ^^ c.c. of Rugby sewage. 



GAS IN GELATINE SHAKE CULTURE, 24 hours at 20 C. 

 From left to right the tubes represent T J n , Tn ' rtiT , TB J TO> Tn ^nr> c.c. of Nottingham crude sewage. 



[To face page 50. 



