696 Leprosy 



tures, giving it a beaded appearance, like the tubercle bacillus. It 

 occurs singly or in irregular groups. There is no characteristic 

 grouping and filaments are unknown. It is not motil^ and has no 

 flagella and no spores. 



Duval found that the cultivated bacilli are longer, more curved, 

 and show a greater irregularity in the distribution of the chromatin 

 than those in the tissues where they are short, slender, and slightly 

 curved. In artificial cultures there is a delicate filamentous ar- 

 rangement of the bacilli, especially where they have become ac- 

 customed to a saprophytic existence. They often contain distinct 

 metachromatic granules analogous to those met with in certain 

 forms of the diphtheria bacillus. They are quite pleomorphous, 

 and in the same culture all forms occur, from solidly staining coccoid 



Fig. 282. Lepra bacilli. Smear from a lepra node stained with carbol-fuchsin 

 (Kolle and Wassermann). 



shapes to slender slightly curved filaments, with numerous chromatic 

 segments and occasional metachromatic granules. Sometimes 

 the organisms are pointed at the ends. 



Czaplewski found that the lepra bacilli in his cultures colored 

 uniformly when young, but were invariably granular when old. The 

 more rapidly the organism grew, the more slender it appeared. 



Staining. -It stains in very much the same way as the tubercle 

 bacillus, but permits of a more ready penetration of the stain, so 

 that the ordinary aqueous solutions of the anilin dyes color it quite 

 readily. The property of retaining the color in the presence of 

 the mineral acids also characterizes the lepra bacillus, and the 

 methods of Ehrlich, Gabbet, and Unna for staining the tubercle 

 bacillus can be used for its detection. It stains well by Gram's 

 method and by Weigert's modification of it, by which beautiful 

 tissue specimens can be prepared. 



Cultivation. Many endeavors have been made to cultivate 



