BACILLUS OF TYPHOID FEVER 409 



sion is made of a loopful of feces in a tube of broth. Into this 

 is dipped a bent glass smearing rod, the excess of fluid is allowed to 

 drip off, and smears are made upon plates of the medium, several 

 plates being smeared without redipping the rod. Colonies of the 

 colon bacillus on these plates will appear opaque, comparatively large, 

 and will produce an acid reaction with consequent reddening of the 

 medium. Typhoid colonies will be smaller, transparent, and without 

 acid formation. These colonies are fished and the microorganisms may 



FIG. 91. BACILLUS TYPHOSUS. Colony in Hiss plate medium, highly magnified. 



be identified by agglutination or by stab cultures in the Hiss tube 

 medium. 



The malachite-green media of Loeffler and others have found 

 less general use than was originally expected, because of the 

 difficulty in obtaining uniform preparations of malachite-green. 

 Peabody and Pratt l have applied the principle of colon-bacillus in- 

 hibition by malachite-green, by adding this dye to broth in the 

 manner described in the section on media (page 137), planting the 

 feces directly into this broth, and, after incubation for several hours, 

 making smears from these tubes upon plates of the Conradi-Drigalski 

 medium. 

 ( 'As a routine method for isolation of the bacilli from stools we our- 



1 Peabody and Pratt, Boston Med. and Surg. Jour., 1908. 

 27 



