Bacilli Resembling the Typhoid Bacillus 663 



"The same in all respects, excepting as to its behavior in saccharose-bouillon; 

 neither gas nor acids are formed in it." 



DIFFERENTIAL CHARACTERISTICS 



Typhoid Bacillus Colon Bacillus 



Bacilli usually slender. Bacilli a little thicker and shorter. 



Flagella numerous (10-20), long, and Flagella fewer (8-10) (peritricha). 



wavy (peritricha). 



Growth not_ very rapid, not particu- Growth rapid and luxuriant. This 



larly luxuriant. character is by no means constant. 



Upon Eisner's, Hiss', Piorkowski's, and Upon Eisner's, Hiss,' Piorkowski's, and 



other media gives characteristic ap- other media gives characteristic 



pearances. _ appearances. 



Upon fresh acid potato the so-called Upon potato a brownish-yellow distinct 



"invisible growth" formerly thought pellicle. 



to be differential. 



Acid-production in whey not exceeding Acid-production well marked through- 



3 per cent. Sometimes slight in or- out. 



dinary media, and succeeded by 



alkali-production. 



Grows in media containing sugars with- Fermentation with ga -production well 



out producing any gas. marked in solutions containing dex- 

 trose, lactose, etc., the usual for- 

 mula being H : CO2 = 2:1. 



Produces no indol. Indol-production marked. 



Growth in milk unaccompanied by Milk coagulated. 



coagulation. 



Gives the Widal reaction with the ser- Does not react with typhoid blood. 



um of typhoid blood. 



Colon Bacillus in Drinking Water. — Much importance attaches to 

 the presence or absence of colon bacilli in judging the potability of 

 drinking waters. 



It is a speculation whether the colon bacilli were originally micro- 

 organisms of the soil that accidentally found their way into the con- 

 genial environment of the intestine and there took up permanent 

 residence, or whether they have always been intestinal parasites and 

 have been discharged with the excrement of animals until the soil 

 has become generally infected with them. However this may be, 

 they are at present found in the intestinal canals of all animals, and 

 in pretty much all soils, their number being greatest in manured soils. 

 From the soil it is inevitable that the organisms shall pass into the 

 surface waters, which with few exceptions will be found to contain 

 them. The numbers, however, can be made use of to indicate the 

 quality of the water, a few organisms indicating that the water is 

 pure, many that it is freely mixed with surface washings. 



As sewage contains as many as 1,000,000 colon bacilli per cubic 

 centimeter and pure water very often o per cubic centimeter (only 

 I cc. being examined at a time), the number of bacilli per cubic 

 centimeter can be expressed as indicating the amount of sewage 

 pollution. The number of colon baciUi in the water is, therefore, of 

 importance in determining its potability, and in cases in which 

 the quality of the water is doubtful, should always be employed. 

 There is no infallible criterion for judging the quality of water, but 

 most American bacteriologists are in accord in concluding that when 



