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and staining more or less the well-known vibrio of cholera, 

 but they differ from this latter in this essential respect, that 

 they do not liquefy gelatine at any period of their growth, 

 forming on this medium non-liquefying translucent, more or 

 less angular colonies. In peptone salt they grow feebly, do 

 not form any marked pellicle on the surface of this fluid, and 

 do not produce nitroso-indol : sufficiently distinct differences 

 from the vibrio of cholera. Besides, this non-liquefying 

 sewage vibrio, when injected, even in large doses, intra- 

 peritoneally into a guinea-pig, causes no disease. This same 

 vibrio was found on Drigalski plates inoculated with the 

 fluid of a mussel derived from a polluted locality, and 

 twice in oysters which had been distinctly polluted with 

 sewage. 



I attribute, therefore, to the presence of this vibrio in 

 Drigalski plates, inoculated from oysters or other shellfish, an 

 important diagnostic value, because this vibrio appears 

 present in sewage in small numbers only, and when, there- 

 fore, present in shellfish is a fortiori strong presumptive 

 evidence of sewage pollution. 



All vibrios form on Drigalski plates bright blue, small, 

 moist, round colonies, and in respect of this marked colour 

 and small size can readily be recognised ; a simple microscopic 

 specimen in the hanging drop shows the actively motile 

 comma-shaped, S-shaped, and shorter or longer spirillar forms. 

 From a cockle derived from a particularly polluted 

 locality black mud on the Upper Orwell I have isolated 

 by the Drigalski plate at 37 C. a motile vibrio which differs 

 from the above non-liquefying sewage vibrio in the following 

 respects: its colonies are bright blue, moist, round, small, 

 raised in the centre that is, conical. After two to three 

 days the colonies reach the diameter of several millimetres. 

 This vibrio liquefies gelatine a little faster than the cholera 

 vibrio, but slower than the vibrio finkler. It grows well in 

 peptone salt water, and forms thereon in several days a 

 pellicle composed of matted masses of wavy or spiral 

 threads ; it does not produce nitroso-indol ; it grows well in 

 litmus milk, which becomes distinctly reddened (acid pro- 



