ISO LABORATORY GUIDE IN BACTERIOLOGY 



consists in transferring the cultures for three consecu- 

 tive days in broth and incubating at 20° C. From the 

 third transfer they are plated in gelatin and a colony 

 from this transferred to slant agar, from which sub- 

 cultures are made. 



SECTION 6 

 ISOLATION OF B. TYPHOSUS FROM WATER 



1. Prepare 10 tubes each of Endo's medium, Dri- 

 galski and Conradi's medium, aesc. bile-salt agar (p. 33). 



2. Prepare plates from water containing B. typhosus 

 from both of these media. 



3. Incubate at 37° C. for 24 hours and isolate the 

 colonies. 



4. Carry the colonies through all media and apply 

 the agglutination test with typhoid immune serum. 



SECTION 7 



STUDY OF REACTION OF BACTERIA ON NEUTRAL- 

 RED BROTH 



Prepare a number of fermentation tubes with dex- 

 trose or lactose broth and add enough of a i per cent 

 neutral-red solution until a decided red color has been 

 imparted. Inoculate these tubes with a variety of 

 colonies from water or sewage plates and note the differ- 

 ence in color reaction after 24 and 48 hours' incubation. 



