80 ELEMENTS OF WATER BACTERIOLOGY 



The important fact that caffein has an inhibitory 

 action on colon bacilli, announced by Roth (Roth, 

 1903) has given rise to much investigation, and offers 

 one of the most promising methods for the isolation 

 of the typhoid bacillus from water. Hoffman and 

 Ficker (Hoffman and Ficker, 1904) developed methods 

 for the isolation of B . typhi from faeces and from infected 

 water by its use in connection with nutrose and crystal 

 violet. For the isolation from infected water solutions 

 were prepared as follows : 



1. Ten grams of nutrose dissolved in 80 c.c. of steril- 

 ized distilled water. 



2. Five grams caffein, in 20 c.c. sterilized distilled 

 water. 



3. One-tenth gram of crystal violet in 100 c.c. water. 

 Solutions i and 2 were mixed by shaking together in a 

 flask, and the mixture poured into a flask containing 

 900 cubic centimeters of the water to be tested; 10 

 c.c. of solution 3 were gradually added, and the whole 

 thoroughly mixed by shaking and then incubated at 

 37 degrees for not over 12-13 hours. At the end of the 

 incubation period loopfuls of the solution were smeared 

 over Drigalski-Conradi plates. 



By this method the B. typhi was isolated from 

 mixtures in river water containing one typhoid bacillus 

 to 51,867 water bacteria and colon bacilli. 



A number of investigations have shown that the 

 action of the caffein is not as markedly selective as at 

 first claimed. Kloumann (Kloumann, 1904) obtained 

 no better results by this method than by the Drigalski- 

 Conradi medium alone, and Willson (Willson, 1905) 



