66 BACTERIOLOGICAL EXAMINATION OF WATER. 



gelatine takes place. In gelatine-tubes a shining orange- 

 coloured expansion forms on the surface, whilst hardly any 

 growth is visible in the depth. On agar there is a bright orange 

 expansion which does not extend much beyond the point of 

 inoculation. In broth there is a slightly orange-coloured 

 deposit, the fluid above is clear and a thin pellicle forms on the 

 surface. On potato it produces a thick and magnificent brilliant 

 red orange pigment, which is, however, restricted to the point of 

 inoculation. It reduces nitrates to nitrites very slightly. It is a 

 short, fat bacillus, forms pairs and short chains. The individual 

 bacilli are motile. 



B. Chrysogloia. 



This organism was first described by Zopf. It was isolated 

 from polluted water by Zimmermann. It is a thin, very motile 

 bacillus of variable length, and often found in chains. It does 

 not form spores. In gelatine plates the colonies, to the naked 

 eye, appear as small golden yellow drops. Under a low power 

 they are seen to be brownish-yellow, granular, round discs. In 

 gelatine-stab, on the surface, there is a circular yellow-ochre 

 growth, which later shows concentric zones and becomes folded ; 

 there is no coloured growth along the stab. In gelatine-streak 

 and on agar a yellow-ochre growth develops. On potato a 

 thick growth gradually appears, which at first has a yellow-ochre 

 colour, but later this changes to an orange-yellow tint. In broth 

 a pellicle forms on the surface and an orange-yellow deposit 

 appears at the bottom. The bacillus grows equally well at 

 blood and room temperatures. It is aerobic and stains slightly 

 with Gram. 



B. Subflavus. 



Found by Zimmermann in the Chemnitz water supply. It 

 forms yellowish-white dots in the depths of gelatine-plates ; on 

 the surface it appears as a yellowish-white shining drop, which 

 forms a flat expansion with an irregular and lobular periphery. 

 Under a low power the surface appears arranged in scales. The 

 gelatine is not liquefied. In gelatine tubes it forms a delicate, 

 greyish-yellow expansion on the surface. On agar it produces a 

 pale yellow growth, which later becomes chrome-yellow or 

 yellow-ochre. It does not grow well on potato, and produces a 



