758 BACTERIAL FLORA OF THE SYDNEY WATER SUPPLY, 



obtained. Nitrates were strongly reduced to nitrites. On potato 

 the growth was light brownish-yellow scarcely distinguishable from 

 the potato, but afterwards it became darker, raised and spread 

 over the surface. Milk was coagulated at 37° with a neutral 

 reaction. 



This organism was separated by Pake's method as well as by 

 those of Bandi and Parietti. The first colonies on gelatine by 

 Pake's method were like those of Proteus mirabilis, but the 

 formation of cochleate strands from the margin of the colonies 

 had ceased by the third transfer in ordinary media and the type 

 became stable. It appears to be Bad. cloaca, Jordan, a gelatine- 

 liquefying form of Bad. coli. 



Bact. coli commune, Escherich. 



The bacterium is a short, stout motile rod with rounded ends ; 

 it measures 0-55-O6 : 0-9-1-8 /*, and is not stained by Gram's 

 method. The flagella are long and generally 5 to 9 in number, 

 arising from places around the organism. The colonies on gelatine 

 are punctiform, but became flat, spreading, white, and moist 

 glistening with a raised centre. Microscopically the deep colonies 

 are yellowish-brown, circular and finely granular with a smooth 

 edge; when crowded upon the plate they appear zonate. The 

 surface colonies appear lacerate-erose and grained (the type of 

 coli). The stab in gelatine is filiform with a flat, thin, translucent 

 white, irregularly spreading nail-head. Gas is given off copiously 

 in glucose-gelatine; the gas collected in the fermentation tube 

 contained 1 part carbon dioxide and 2 parts hydrogen. The 

 colonies on agar are translucent white, round, moist glistening 

 and raised centrally. Microscopically the colonies are rounded, 

 finely granular and smooth-edged. The older colonies have a zone 

 of large granules near the margin. The stroke on agar is white, 

 moist glistening and broad, the margin smooth. Litmus-lactose- 

 agar is permanently reddened and gas bubbles are distributed 

 throughout the medium. Bouillon becomes turbid and forms a 



