ISOLATION. 

 FIG. 126. 



273 



Hiss' plate media : small light colony (<) is composed of typhoid bacilli ; large 

 colony (c) of colon bacilli. (Hiss.) 



juice. Either litmus-paper or phenolphthalein may be used 

 to determine the reaction, which should be just perceptibly 



FIG. 127. 



\ 



Colony of typhoid bacilli highly magnified. (Hiss.) 



acid. The solution is then heated and 10 per cent, of nutri- 

 ent gelatin added, after which the medium is again neutralized 



18 Bact. 



