ORGANISMS OF SANITARY SIGNIFICANCE ON GRAINS 213 



The following four cultures are without doubt " colon forms," 

 although they fail to give typical reactions in a few cases: 



Two cultures from feces failed to reduce nitrates. 

 One culture from the North River, Salem, did not ferment lactose. 

 One culture from feces failed to ferment any of the three sugars and rendered 

 milk alkaline. 



Thirteen cultures from cornmeal, corn, milk, flour, malt, buck- 

 wheat, oats, and laboratory stocks of B. acidi lactici were acid- 

 producing organisms that departed widely in character from those 

 just described. These on examination proved to be mostly strep- 

 tococci, although during this portion of the work but little study 

 was given to them. 



FERMENTING POWER. 



The fermenting power, as measured by acid production, was 

 taken as a further means of comparing these apparently identical 

 organisms. For this purpose the cultures were grown in 2 per 

 cent dextrose broth at 37 for 48 hours, and the amount of acid 



N 

 determined by titrating 5 c.c. of this solution against NaOH. 



For fairer comparison the same number of cultures from each of 

 the two sources were taken. Twenty-one cultures of B. coli from 



N 

 unpolluted sources required an average of 1.15 c.c. of NaOH 



to neutralize 5 c.c. of the cultures. Twenty cultures of B. coli from 



N 

 feces required an average of 1.13 c.c. of NaOH. Ten cultures 



N 

 of streptococci required an average of i . 35 c.c. of NaOH. 



PATHOGENIC PROPERTIES. 



As a final test for this series the pathogenic power of the bacteria 

 toward guinea-pigs was studied. Three cultures were chosen at 

 random from each of the two lots, and fresh broth cultures prepared 

 for use as an inoculating medium. 



For the first experiment 0.5 c.c. of a culture from cornmeal 

 was injected subcutaneously into a healthy guinea-pig, and a like 

 amount of a culture from an infected peritoneum into another animal 

 of equal weight. The animals exhibited symptoms of fever after 

 about 48 hours, but on the third day appeared more nearly normal. 



