456 BACTERIAL FLORA OF THE SYDNEY WATER SUPPLY, 



Bacterium croceum, n.sp. 



Shape, etc. — An actively motile rod with rounded ends, measuring 

 0-5-0-6: 2-3 /x; it occurs singly, in pairs, chains and threads. It 

 is stained by Gram's method. The organism grows best at 22° C. 

 No spores were observed. It grows well at 37°. 



Agar plate. — The colonies are circular, raised, moist glistening 

 and buff-coloured. When magnified they are seen to have a 

 smooth, sinuous edge and a folded or grained internal structure. 

 The deep colonies are irregular, moruloid and slightly ciliate. 



Agar stroke. — There is formed a deep yellow, moist glistening, 

 luxuriant, spreading and slightly raised laj-er. The edge is at 

 first lacerate, but becomes smooth and the colour deepens to a 

 light orange. 



Gelatine plate. — The colonies are pale buff and rounded within 

 a zone of softened gelatine. The surface colonies when magnified 

 (60 times) are seen to have a brownish centre and a colourless, 

 irregularty lobed margin, within which the colony appears 

 crumpled. The deep colonies are zonate, the zones being coloured 

 different shades of brown; the marginal zone appears greenish. 



Gelatine stab. — The growth in the deep is very slight. The 

 surface growth is deep yellow, depressed and restricted ; the 

 medium in the neighbourhood of the film is softened. The upper 

 part of the stab becomes, after 1 4 days, faintly tuberculate. 



Glucose-gelatine. — No gas is produced. 



Bouillon. — The medium becomes turbid with floating floccules 

 and there is formed a scanty, white, filamentous precipitate. 

 There is no film produced and no indol formed. 



Nitrate-bouillon. — There is no growth in this medium. 



Milk. — The medium is unaffected. 



Potato. — There is no growth either at 15°, 22° or 30° C. 



The absence of growth upon potato, the brilliant deep yellow 

 colour upon agar and the slow liquefaction of gelatine media 

 separate this organism from all others that have been previously 

 described. The nearest ally is perhaps the non-motile Bac. fuscus 

 llquejaciens, Dyar. 



