BACILLUS-COLI-LlKE BACTERIA FROM FECES AND SEWAGE 7 



TABLE 1 



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



IN GLUCOSE 



acid-production to the source, to the MacConkey types, and to the 

 Voges-Proskauer reaction is also indicated. 



The mode for acid-production by all strains is at 1.9% normal, 

 with the mean at 1.8% normal acid. 



The means or average quantities of acid formed by the MacConkey 

 types indicate that Types III (communior) and I (acidi-lactici) pro- 

 duce about equal quantities of acid (1.84 and 1.85% normal respec- 

 tively), while Type II (communis) forms somewhat less (1.77%), 

 and Type IV (aerogenes) the least amount (1.71%). A comparison 

 of Type IV, which forms the smallest quantity of acid, with Type I, 

 which gives the greatest amount, indicates that the means tend to exag- 

 gerate the difference between the two types in ability to form acid 

 from glucose. Type I has a well-defined mode at 1.90% and Type IV 

 has a very indistinct mode at about the same point. The standard 

 deviation in Type IV is 0.43, or three times as great as the difference 

 between the means of the two MacConkey types. Similar observations 



