BACILLUS TYPHOSUS. 



439 



medium will be found very satisfactory. The colonies, 

 as a rule, appear characteristically in twelve to eigh- 

 teen hours, and thus give a quick method of diagnosis. 

 The two media together (Capaldi and Eisner) work 

 excellently, as one is an aid to the other. When 

 many colonies of the typhoid bacilli were present the 



FIG. 57. 



Colonies of colon bacilli. Capaldi medium slightly magnified. 



differentiation was usually easily seen upon both media, 

 and the two together made diagnosis almost certain. 

 The bacilli from the suspected typhoid colonies can be 

 quickly tested sufficiently for practical purposes on the 

 Hiss tube medium and by the reaction between the 

 bacilli and the serum from an immunized horse. 



As to the comparative merits of these three media, 

 it is probably safe to say that any one of them will, in 

 the hands of one accustomed to them, reveal the typhoid 

 bacilli, if they are present, except perhaps when they 



