358 A MANUAL OF BACTERIOLOGY 



course of weeks or even months, and about half the cases 

 end in recovery. 



The Glanders Bacillus 



The glanders bacillus (B. [Pfeifferella] mallei) is an 

 obligatory parasite with the equine species for its normal 

 host. It hardly grows on artificial media below about 



FIG. 39. Horse affected with farcy (McFadyean). 



20 C., and probably cannot maintain a saprophytic 

 existence outside the animal body. 



Morphology.- The glanders bacillus in the tissues 

 varies between 2 ^ and 5 ^ in length, and is generally 

 straight, though sometimes slightly curved. The bacilli 

 are usually irregularly scattered, and do not tend to form 

 colonies. In stained preparations they often appear more 

 or less beaded, or may exhibit bipolar staining, but some 

 stain uniformly. The bacilli from young cultures not 

 more than twenty-four hours old are almost always 

 short rods, a little thicker than those found in the lesions 

 (Plate VIII, a). In old broth cultures the surface growth 

 is largely composed of filaments, which do not show any 



