188 ELEMENTS OF WATER BACTERIOLOGY 



BIOCHEMICAL REACTIONS OF 2079 ORGANISMS OF THE 

 COLON GROUP 



(KONRICH, 1910) 



enrichment in sugar broths. Such an enrichment would 

 undoubtedly tend to increase the proportion of typical 

 B. coli. Konrich's own experiments on the storage 

 of pure cultures of colon bacilli in water showed a gen- 

 eral, though not invariable, relative increase of atypical 

 forms as the sojourn in water became long continued. 

 Houston (191 1) has recently pointed out the danger 

 that the selective action of enrichment media may 

 confuse the normal relations of the bacterial flora; 

 and in order to obtain a more accurate idea of the 

 relations involved he made an elaborate study of raw 

 water, stored water, and stored and filtered water by 

 direct plating, preceded by the use of various physical 

 concentration methods. The results indicated in the 

 table on p. 189 are of interest. 



