452 BACTERIAL FLORA OF THE SYDNEY WATER SUPPLY, 



Bacillus circulans, Jordan. 



The colonies, in gelatine, are white and sink into the medium, 

 forming a cylindrical pit or hole which widens out at the top 

 when the colony has grown as far as it can downwards. The 

 medium is consumed and not liquetied. With a sixty-fold magni- 

 fication the dark granular contents of the colony are seen to be 

 in active motion, apparently circulating round the walls of the 

 pit. The deep colonies are at first circular, irregular or amoeboid, 

 but the latter soon become round and rapidly open to the surface. 

 In gelatine the stab assumes the form of a hollow inverted cone. 

 No gas is produced in glucose-gelatine. The organism is a rod 

 with rounded ends and forms a terminal round spore which 

 becomes 1 fi in diameter. The vegetative forms measure - 5 : 2-3 fi 

 and are actively motile. They retain the colour when treated 

 by Gram's method. Both on agar plate and agar slope there is 

 formed an amoeboid growth which rapidly spreads over the entire 

 surface. In milk the casein is slowly peptonised without coagula- 

 tion. Bouillon becomes turbid and there is formed a white film 

 and a flocculent and filamentous precipitate. No indol is formed 

 and nitrate is not reduced. A drab-coloured growth spreads 

 over the surface of potato. 



Cladothrix dichotoma, Cohn. 



On gelatine and agar media, the colonies grow as scattered 

 white points which become circular, porcelain-white and raised. 

 The larger colonies develop a marginal ring within which are 

 little central crusts. A deep brown colour is diffused into the 

 media. Gelatine is not liquefied. The fungus appears micro- 

 scopically as a narrow branching mycelium, - 4/x in breadth, and 

 broken up into short rods and threads. The colonies on agar 

 appear, when magnified, circular and opaque with a ciliate 

 margin. 



Bacterium album mesentericum, n.sp. 



Shape, etc. — A slender rod with rounded ends, averaging 

 0-3 : 1-5 fi. It is slowly motile and is decolourised by Gram's 



