THE ROLE OF THE COLON BACILLUS. 91 



2. A type fermenting mannite, but not maltose or saccharose. 

 No indol. 



3. An indol producer which actively ferments mannite and 

 maltose, 



B. COLI, B. LACTIS AEROGENES, B. CLOACAE. 



While the colon bacillus chiefly inhabits the large intestine, the B. 

 lactis aerogenes is to be found in the upper part of the small intestine. 

 While they may be separated on the ground of motility, yet it is by the 

 greater fermentative activity of the B. lactis aerogenes that they are 

 best separated. Some consider them as only representing different 

 strains of the same organism. Some consider that the B. coli produces 

 a bactericidal substance which inhibits the growth of, or destroys 

 pathogenic bacteria which may have passed the destructive influences 

 of the gastric fluid; others that this effect is due to their free growth 

 and the development of phenol and various putrefactive substances. 

 The probable importance of the colon bacillus in protecting the organ- 

 ism is shown by the fact that where numerous colonies of pathogenic 

 organisms may be cultivated from feces we may find a diminution in 

 number or absence of the colon bacillus. This condition may be 

 observed in infections with the organisms of dysentery, cholera, typhoid 

 and paratyphoid. While its normal function is probably protective, 

 yet the B. coli is an important pathogenic agent, it being frequently 

 the organism isolated from purulent conditions within the abdominal 

 cavity, especially in appendicitis and lesions about the bile ducts. 

 It is particularly prone to cause lesions of the bladder and pelvis of 

 the kidn.ey. In the treatment of colon cystitis by vaccines of dead 

 colon bacilli, the most brilliant results in opsonic therapy have been 

 obtained. 



Sir A. Wright thinks that certain cases of mucous colitis may be 

 due to colon infection and that vaccination may cure them. The 

 colon bacillus is fully considered under the bacteriology of water. 



B. cloacae was isolated first from sewage by Jordan. It is a rapid 

 liquefier of gelatin, and in its reaction^ with sugars and litmus milk 

 resembles the colon bacillus. 



