196 ELEMENTS OF WATER BACTERIOLOGY 



Group IV which ferments adonit, but does not form 

 indol or liquefy gelatin, occupies a somewhat inter- 

 mediate position, appearing in waters which have been 

 fairly recently polluted and later disappearing again. 

 Finally B. Griinthal and B. vesiculosus (MacConkey's 

 Group I, negative in both saccharose and dulcite) 

 and B. cloacae and B. coscoroba (of MacConkey's 

 Group IV, dulcite negative and saccharose positive), 

 are highly resistant organisms which occur in relatively 

 high proportions in stored waters. B. cloacae is most 

 abundant in bottom sediments and B. Griinthal and B. 

 vesiculosus in sunned surface-waters. 



The moral drawn by Major Clemesha is that for 

 Indian conditions with waters stored in warm sunned 

 lakes and large rivers, where sensitive faecal bacteria 

 have ample opportunity to die out and resistant faecal 

 bacteria have an ample opportunity to multiply, it is 

 not proper to condemn water containing any members 

 of the colon group without distinguishing between the 

 more and the less resistant forms. For example, he 

 quotes 239 examinations of which only 74 showed no 

 B. coli according to the English standard, which closely 

 corresponds to our own, while 165 showed what we 

 should call positive results. Of the 165, however, 69 

 contained only the highly resistant B. Griinthal and 

 59 contained mixtures of other forms not belonging 

 to MacConkey's Group II (saccharose negative, dulcite 

 positive). Thus of the 239 samples 31 per cent would 

 have been passed by Houston's standard, 53 per cent 

 would have been condemned by Houston's standard, 

 although containing only resistant forms which Clemesha 



