438 BACTERIOLOGY. 



is the typhoid (Fig. 56). However, it is often trans- 

 parent, without the refractive granules; sometimes 

 with a nuclear centre, and sometimes of equal con- 

 sistency throughout. Streptococci simulate typhoid, 

 but a high-power lens will show the coccus. 



FIG. 56. 



Colonies of typhoid bacilli, on Capaldi medium, slightly magnified. 



Colon colonies are usually much larger than the 

 typhoid; a decided brown color, very large, refractive 

 granules, and in general quite different in appearance 

 (Fig. 57). 



The best way to work with the Capaldi medium is to 

 make several plates with different typhoid cultures, 

 observe carefully all the variations in the colonies, and 

 bear these in mind when working with the mixed 

 plates. After these precautions have been taken the 



