BACILLUS-COLI-LlKE BACTERIA FROM FECES AND SEWAGE 13 



strains considered, the average acid-production was 0.77%, with a 

 very distinct mode at 0.7% normal acid. The frequency distributions 

 of the organisms from different sources, of the MacConkey types, and 

 of the Voges-Proskauer reaction with respect to acid-production in 

 maltose are shown in Table 5. One organism apparently fails to show 

 acid but forms gas. This neutral reaction is presumed to be due to 

 reversion. 



TABLE 5 



RELATION OF SOURCE, MACCONKEY TYPE, AND VOGES-PROSKAUER REACTION TO ACID-PRODUCTION 



IN MALTOSE 



Each of the MacConkey types has a sharply defined mode at 0.70% 

 normal. The means for the types are 0.76, 0.73, 0.76, and 0.83% 

 normal acid respectively. There is no correlation between quantitative 

 acid-formation from maltose and the MacConkey types. 



The relation of acid-formation from maltose to the source of 

 Bacillus-coli-like organisms is not at all striking. The mode for each 

 source is at 0.7% normal acid. The trend of the variation among the 

 strains from horse, cow, pig, and sewage, is beyond the mode, so 

 that the means are 0.81, 0.81, 0.77, and 0.83% normal acid respec- 



