176 BACTERIA 



it plays rather a subordinate pathogenic role, but it has been 

 found the causal agent of some cases of suppurative appendicitis, 

 peritonitis, and cystitis. It may attack the lungs and meninges 

 of feeble children, and cause death by setting up a pneumonia or 

 meningitis. During the agonal period in wasting diseases it may 

 cause terminal infection and hasten death. Colon bacilli encysted 

 in the liver and kidney have been found by Adami in cirrhosis of 

 these organs, and it is believed by him to be partly the cause of 

 these diseases; chronic infections of the rectum are due to this 

 organism. 



Agglutination. Animals immunized against colon bacilli by 

 repeated injections, exhibit agglutinins in their blood. 



The differentiation of the typhoid from the colon bacillus is 

 largely accomplished by noting the chemical reactions of both 

 organisms in culture media. The chief differences are : 



1. The typhoid bacillus has more flagella than the colon, and is 

 much more motile. 



2. On gelatine culture plates, the typhoid colonies develop 

 more slowly than the colon, and are much more delicate and trans- 

 parent. If litmus is present the colon colonies are red, the 

 typhoid bluish. 



3. In media containing dextrose, or lactose, gas is produced by 

 the colon, but not by typhoid. 



4. In peptone solution the colon produces indol, while the 

 typhoid does not. 



5. Milk is coagulated by the colon, but not by the typhoid. 



6. Dn potatoes colon grows much more luxuriantly than typhoid. 



7. Typhoid reddens neutral red; colon changes it to bright 

 yellow. 



8. The m.ost important test is the agglutinative one. Typhoid 

 is clumped by anti-typhoid sera, highly diluted, while the colon 

 is not. 



No anti-sera of value have been found for colon bacillus infec- 

 tion, but bacterins have been used with much benefit. 



