Isolation of the Colon Bacillus. 87 



strong acid reaction is developed in most sugar-containing 

 media. The organism reduces nitrates to nitrites and 

 sometimes to ammonia. It reduces neutral red, changing 

 its color to canary yellow with a greenish fluorescence. It 

 grows in the Capaldi-Proskauer media, forming acid in the 

 albumin-free medium, No. i, and giving a neutral or 

 alkaline reaction in the pepton-mannite medium, No. 2. 

 It coagulates casein in litmus milk, and reduces the litmus 

 with subsequent slow return of the color (red), and forms 

 indol in pepton solution. Many cultures of this organism 

 are fatal to guinea pigs when the latter are inoculated 

 subcutaneously with one-half c.c. of a twenty-four-hour 

 bouillon culture, and most cultures produce death when 

 this amount is inoculated intraperitoneally. Although 

 not a spore-forming bacillus, and in general not possessing 

 great resistance against antiseptic substances, B. coli is 

 less susceptible to phenol than are many other forms, 

 especially certain water-bacteria. 



A word may be added as to the fermentative powers of 

 the colon group in other carbohydrates than dextrose and 

 lactose. Of the monosaccharides, galactose, like dextrose, 

 is always fermented; and among the polysaccharides, 

 maltose and xylose are broken up as well as lactose. 

 Inulin is not attacked. The alcohols, mannite and dulcite, 

 are fermented by some strains and not by others. The 

 colon group, as Smith (1893) long ago pointed out, may 

 be divided into two distinct subtypes according to the 

 action of the organisms upon saccharose. One subtype 



