THE COLON BACILLUS 107 



valuable as it is very difficult to immunize rabbits with a Shiga strain on account of 

 its great toxicity. 



There seems to be very little agglutination power in the serum of convalescents 

 from Shiga strains. Flexner strains give agglutination, but early in convalescence 

 the serum is not apt to have a titre of more than 1-50. 



Morgan has reported as the cause of certain cases of bacillary dysen- 

 tery a bacillus known as B. Morgan, No. i. It is motile, produce indol, 

 and in glucose bouillon gives a very slight amount of gas. 



It does not change mannite and does not produce a primary acidity in litmus 

 milk. This organism is a frequent cause of summer diarrhoea of children. Flies 

 from houses with such cases often show Morgan's bacillus. A dysentery type much 

 like the Flexner Strong strain is often found in the enteric affections of children in 

 the United States. 



In Japan, dysentery-like epidemics of a very fatal disease, termed 

 ekiri, occur among young children. The organism is very motile, pro- 

 ducing gas and acid in glucose but not in lactose media. It is reported 

 to at times show indol production. Apparently a member of the 

 Gartner group. 



More recently a strain of dysentery bacilli, known as Type F, has 

 been considered of importance. This organism is very closely related 

 to the Flexner strain and only differs from it in that it requires about 

 48 hours to turn mannite litmus media pink and that maltose litmus re- 

 mains blue. An organism showing similar cultural characteristics has 

 been recently recovered from faeces of laboratory rabbits by German 

 workers investigating the problem of whether certain animals might 

 serve as carriers for dysentery. 



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. B. lactis aerogenes is closely related to the 

 pneumobacillus and at times shows capsules. 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 juice; others that this effect is due to their free 



