COLON-AEROGENES GROUP OF BACTERIA 255 



(1904) obtained a large number of similar bacteria from fruits, 

 plants and seeds, and Metcalf (1905) observed the same kind of 

 organisms on flowers, fruits and grains. Bettencourt and Borges 

 (1908) found 12 strains of lactose-fermenting organisms on 

 vegetables and cereals, but only half of these were typical B. coli. 



McConkey found atypical colon bacilli to constitute 56.2 per 

 cent of the 121 strains isolated from raw water. Houston showed 

 that 13 per cent of his 243 strains from raw water, 5.3 per cent 

 from stored water and 3.2 per cent from stored and filtered water, 

 were atypical B. coli. More recently Rogers and his associates 

 (1915-1916) found about 91 per cent of the bacteria on grains, 

 and 33.3 per cent of those in water to belong to the group of 

 non-fecal coli-like bacteria. Their investigations were soon fol- 

 lowed by those of Rogers, Clark, etc., Hulton, Greenfield, Levine, 

 Burton and Rettger, Winslow and Kligler, and others. 



Houston (1897-1898), studied a large number of soil samples, 

 and came to the important conclusion that true colon bacilli 

 are rarely found in virgin soil, but are present in large numbers 

 in soils that have been grossly polluted with animal matter. 

 Konrich (1910) drew the same conclusions from his examination 

 of 547 samples of soils. Both of these investigators failed, how- 

 ever, to differentiate typical B. coli from the non-fecal type 

 (aerogenes-cloacae) . Johnson and Levine (1917) found that the 

 aerogenes-cloacae types are the predominant bacteria of this 

 group in the soil. Burton and Rettger (1917) examined 1000 

 samples of soil, leaves, flowers, etc., and concluded that the 

 cloacae type predominated over its close allies, which is in harmony 

 with the results of Clemesha, who observed that this organism 

 could be isolated readily from soils. 



Conflicting reports on the distribution of coli-like bacteria 

 in nature have appeared, however. Clark and Gage (1903) 

 obtained negative tests with grains. Gordon (1904) was unable 

 to isolate lactose fermenters from bran except that of inferior 

 quality. Winslow and Walker (1907) failed to find them in a 

 thorough search in 178 samples of grains and 40 samples of 

 grasses. Neumann (1910) experienced the same difficulty with 

 fresh fruits, but found them on fruits and others foods which 

 had been exposed to human contamination. 



