QUALITATIVE BACTERIOLOGICAL ANALYSIS. 67 



faint, loamy yellow colour. It is a thin, slowly motile, small 

 bacillus, grows best at room-temperature, and is not stained by 

 Gram's method. 



The Orange-red Water Bacillus. 



Described by Adametz-Wichmann. In gelatine plates it 

 grows very slowly, forming orange-red centres, which under a 

 low power are finely granular and brown in colour. The 

 colonies in the depth appear to be colourless. In gelatine tubes 

 it grows slowly on the surface, forming a moist, slimy layer of an 

 orange-red colour. The gelatine is not liquefied. It is a long, 

 thin, non-motile bacillus. Its cultures appear to be identical 

 with those of the B. aurantiacus. 



B. Luteum. 



Described by List and Adametz. In gelatine plates it forms 

 irregular, slimy, orange-yellow centres which gradually grow 

 out into flat expansions ; under a low power they appear to 

 consist of club-shaped, coarsely granular, zooglcea masses, each 

 of which is made up of several pieces. No liquefaction occurs. 

 In gelatine tubes it forms an orange yellow expansion on the 

 surface, but grows slowly in the depth. It coagulates milk. It 

 forms elliptical cells which are not motile. 



The B. fulvus described by Zimmermann appears to stand 

 between the liquefying and non-liquefying varieties. It is 

 a small non-motile bacillus. Media are coloured a gamboge- 

 yellow. Gelatine is liquefied after some weeks. 



GROUP VII. 



This group includes the micro-organisms which produce a 

 violet blue or indigo colour in the nutrient media. 



B. Janthinus (Zopf) or B. Violaceus. 



This bacillus was first isolated by Zopf ; it has also been 

 found by Zimmermann in the Chemnitz water supply and by 

 Proskauer in the Spree. In gelatine plates the colonies at first 

 are milk-white ; later, they grow out, and the margin is irregular 

 and thinner than the centre ; each colony acquires a violet colour 



