CHAPTER XL 



QUALITATIVE ANALYSIS continued. 



THE PROTEUS GROUP. 



MEMBERS of the proteus group are often found in sewage, but 

 are very rare in pure waters. They do not necessarily indicate 

 sewage contamination, but if they are found in conjunction 

 with B. coli there is very little doubt that such pollution has 

 occurred. The three chief members of the group were first 

 isolated from putrid meat by Hauser. 



Proteus Vulgaris. 



Gelatine Plates. The young colonies are very variable in 

 outline ; they are generally yellowish-brown in colour and 

 rapidly liquefy the gelatine. Under a low power the edge of 

 the colony may be seen to be set with fine bristles, which appear 

 to be continued into the centre of the colony ; from the margin 

 wandering processes grow out over the gelatine, and in these 

 the bacilli are seen to be packed side by side. Sometimes 

 instead of the colony with a bristly edge, there appears an oval 

 or spindle-shaped form from which processes or " swarmers," 

 often bent on themselves, run out all over the gelatine. In the 

 depth of the gelatine oval colonies are seen in which the bacilli 

 appear packed in concentric circles. Zooglcea forms are also 

 common. After twenty-four hours incubation the plates to the 

 naked eye often show nothing but circular or irregular pits of 

 liquefaction with slimy contents. 



Gelatine-stab. The gelatine is rapidly liquefied in a more or 

 less funnel-shaped manner, and at the bottom of the liquefac- 

 tion an opaque flocculent mass is seen. 



Agar. A moist greyish-white growth. 



Potato. A dirty yellowish-white moist growth. 



