658 Bacillus Coli 



that is almost universally prevalent in the intestines and fecal evacu- 

 ations of man and the higher animals. 



Distribution. — -It is habitually present in the feces of animals, and 

 in water and soil contaminated by them. Soon after birth the or- 

 ganism finds its way into the alimentary canal and permanently 

 establishes itself in the intestine, where it can be found in great 

 numbers throughout the entire life of the individual. It is almost 

 certainly identical with Bacillus pyogenes foetidus of Passet, and so 

 closely resembles B. acidi lactici that Prescott* believes them to be 

 identical. It may also be identical with Bacillus lactis aerogenes. 

 Bacillus cavicida, and other separately described species. 



Morphology. — The bacillus is rather variable, both size and form 

 depending to a certain extent upon the culture medium on which it 

 grows. It measures about 1-3 X 0.4-0. 7/i. It usually occurs in the 

 form of short rods, with rounded ends but coccus-like and elongate 

 individuals may be found in the same culture. The bacilli are usually 



Fig. 262. — Bacillus coli; superficial colony two days old upon a gelatin 

 plate. X 21 (Heim). 



separate from one another, though occasionally joined in pairs, are 

 sluggishly motile, and provided with flagella, which are variable in 

 number, usually from four to a dozen. The organisms from some 

 cultures swim actively, even when the culture is some days old; 

 others are sluggish even when young and actively growing, and still 

 other cultures consist of bacilli that scarcely move at all. It forms 

 no endospores. 



Staining. — The bacillus stains well with the aqueous solutions of 

 the anilin dyes, but not by Gram's method. 



Cultivation. — ^It is readUy cultivated upon the ordinary media, 

 at temperatures varying from 10° to 4S°C., the optimtmi being about 

 37°C. 



Colonies. — Upon gelatin plates the colonies are visible in twenty- 

 four hours. Those situated below the surface appear round, yellow- 

 * Society of American Bacteriologists, Dec. 31, 1902. 



