87 



would distinguish the Bact. coli of the human intestine from those in the 

 soil or of animal intestinal origin. 



Rogers suggested that fermentation of adonite was a convenient differ- 

 ential index for the separation of the human from the grain strains of Bact. 

 aerogenes. Of 46 human strains, all fermented adonite, whereas of 111 

 strains isolated from grains, only 12.6 percent were adonite fermenters. 



This differentiation was incorporated in the Standard Methods of 1917, 

 which divided the Bact. aerogenes forms into two subgroups, (1) the adonite 

 fermenting type supposedly of human origin and (2) the adonite non-fer- 

 menting type regarded of non-fecal origin. 



Other investigators, however, do not agree as to the value of adonite 

 for this purpose. Monfort assigns to adonite about the same significance 

 as to dulcite, saying that it is of rather dubious importance and of little 

 significance as an index of pollution. Winslow and Cohen, in a study of 

 water of known sanitary quality, found no evidence to support the conten- 

 tion that adonite fermentation by the Bact. aerogenes was indicative of fecal 

 origin. In fact, their results were exactly the converse; 59 percent of the 

 aerogenes strains from polluted water fermented adonite, whereas 90 per- 

 cent from non-polluted sources were adonite fermenters which would in- 

 dicate that the adonite fermenters (fecal varieties) were more prevalent 

 in non-polluted water. 



Chen and Rettger report 152 (34%) of their 447 aerogenes strains 

 from soil to be adonite fermenters. It would appear, therefore, that adonite 

 fermentation can not be considered, for the present at least, a reliable 

 criterion for the identificaiton of Bact. aerogenes of fecal origin. 



In 1905, MacConkey first subdivided the colon group into separate 

 species, suggesting that information may thereby be obtained as to the 

 relative value of specific members of the group as indicators of pollution. 

 Clemesha advocates strongly such consideration and points out that the 

 dulcite non-fermenters 1 ( MacConkey 's groups 1 and 4) are resistant in 

 water, whereas the dulcite fermenting forms (groups 2 and 3 of MacConkey) 

 are sensitive, dying off rapidly. He contends that for tropical water a 

 distinction must be made between the resistant dulcite non-fermerters and 

 the non-resistant dulcite fermenting organisms. Whether these sugges- 

 tions are as applicable to the temperate climate of our country is doubtful 

 except possibly the hottest season of the year or in our tropical possessions. 

 In this connection it should be pointed out that the observations of Houston 

 do not agree at all with those of Clemesha as to the relative resistance of the 

 dulcite fermenters and non-fermenters. The so-called sensitive dulcite 

 fractors were less prevalent while the supposedly resistant forms were found 

 to be more numerous in raw than in stored or filtered water. 



Levine suggests that there is some correlation between the species of 

 the coli section and their source, and that the determination of species may 

 have some bearing upon interpretation of analyses. 



From a study of 333 colon strains isolated from various sources, as 

 indicated in Table L., he observes with reference to the coli section that 

 Bact. communior was extremely abundant in the horse (79%) and sheep 



