BACILLUS COLI COMMUNIS. 285 



abscesses, and especially in suppurations in the vicinity of 

 the intestines. It is believed that in inflammatory conditions 

 of the intestinal tract the organism may become pathogenic. 

 Immediately after death it is found in all the tissues of the 

 body. When injected into the peritoneal cavity of animals, 

 death results in from eight to ten days. Cultures of the 

 colon bacillus obtained from the intestinal discharges of 

 persons suffering from cholera and cholera nostras are much 

 more virulent than those obtained from pus or normal feces. 

 The virulence is increased by rapid passage of the germ 

 through animals, and is diminished by frequent transplanta- 

 tion. 



It is possible to immunize animals against infection with 

 the colon bacillus by inoculating them with gradually increas- 

 ing doses of either dead or living cultures. 



The colon bacillus may be absorbed from the intestinal 

 canal and produce inflammations in other organs, especially 

 the urinary bladder, the gall-bladder, and all the biliary chan- 

 nels. Multiple abscesses of the liver are not infrequently 

 caused by the colon bacillus. It has often been found in the 

 intestinal discharges of infants suffering with cholera infantum 

 and in dysentery. Other infections in which the colon bacil- 

 lus has been found in large numbers are meningitis, solitary 

 abscess of the liver, endocarditis, bronchopneumonia, ure- 

 thritis, and in abscesses of the skin and subcutaneous tissues. 



McFarland believes that the colon bacillus is not a single 

 species of bacterium, but merely a name applied to a group 

 of organisms whose appearance is too similar to permit of 

 their differentiation. This group is usually referred to as the 

 colon group. 



The method of differentiating between the colon and typhoid 

 bacilli has been described in the preceding chapter, but it may 

 be well to mention again points of difference : 



1. The colon bacillus is shorter, thicker, less motile, and 

 has fewer flagella than the typhoid bacillus. 



2. Its growth is more rapid and very luxuriant. 



3. On potato it forms a thick brownish membrane which is 

 very visible. The growth of the typhoid bacillus is colorless 

 and usually invisible. 



