MICROCOCCI IN WATER 129 



seen on the surface, and granules form along the track. 

 The gelatine is not liquefied. A slimy coating develops on 

 potatoes and agar, and prominences and hollows appear on 

 old cultures. The yellow pigment shows itself capable of 

 resisting the action both of acids and alkalies. 



Micrococcus aurantiacus was also discovered by Cohen, 

 and consists of small immotile elements, which sometimes 

 occur in the form of diplococci. The colonies on plates as 

 well as thrust- cultures in gelatine show a fine orange -yellow 

 colour, and the growths on agar and potatoes are also 

 beautifully tinted. Gelatine is not liquefied. 



Micrococcus fervidosus. Adametz has described the 

 Mi< rococcus fn-r'ulnxiis, which consists of small elements 

 whose colonies are first seen on the gelatine plate as dots of 

 a pale yellow colour, becoming brown later. In gelatine 

 thrust-cultures a granular growth appears along the canal 

 and a thin coating on the surface. Superficial cultures on 

 agar show a gloss like that of mother-of-pearl, and a dirty 

 white deposit occurs on potato. Abundant bubbles of gas 

 are disengaged on glycerine jelly, but there is no liquefaction 

 of the gelatine. 



Micrococcus carneus. This micro-organism, described by 

 Zimmermann, is distinguished by the cluster-like arrange- 

 ment of its elements, which are immotile. Round reddish- 

 coloured colonies appear on the gelatine plate, but in older 

 cultures the red tint fades towards the circumference. In 

 thrust-cultures the colour only appears on the surface. A 

 flesh-red, or sometimes violet layer develops on agar and 

 potato. 



Micrococcus concentricus. This, like the preceding, was 

 found by Zimmermann in the Chemnitz water-supply. 

 The cocci are arranged in clumps, and occur on gelatine 

 plates in the form of blue-grey dots, while thrust - 

 cultures in gelatine show on the surface a greyish-brown 



K 



