350 



THE LEPROSY BACILLUS 



SECTION II. MORPHOLOGY. 

 1. Microscopical appearance. 



A. In human lesions. The leprosy bacillus is a slender rod-shaped organism 

 with rounded ends, and of the same size as the 

 ^i tubercle bacillus (5-6/x x 0'5/x). 



Though it may be very slightly curved, it is gener- 

 *^ ally speaking straighter than the tubercle bacillus; 

 occasionally the ends are slightly swollen. 



Staining reactions. The leprosy bacillus, like the 

 tubercle bacillus, stains by both Ehrlich's and Ziehl- 

 Neelsen's methods, but is more acid-fast and therefore 

 more difficult to decolourize than the tubercle bacillus. 

 ^e two Bacilli may therefore be differentiated by 

 this characteristic. The leprosy bacillus retains the 



violet in Gram ' s method. 



The following table gives the differential charac- 

 teristics of the two bacilli. 



-tf 





^ \ft 



FIG 213 Bacillus of 

 leprosy in a 'film fron^nasai 



met'hod. x Z io5o." 



LEPROSY BACILLUS. 

 Stains with aqueous solutions of the 



basic aniline dyes. 

 Stains readily by Gram's method. 



Stains with Ziehl- Neelsen's and Ehr- 

 lich's solutions and resists decolour- 

 ization for a long time. 



Stains by Baumgarten's method (vide 



infra). 

 Bacilli present in very large numbers 



within the cells of the leprous nodule. 



TUBERCLE BACILLUS. 

 Does not stain with aqueous dyes con- 



taining no mordant. 

 Stains with difficulty by Gram's method 



(p. 307). 

 Stains with Ziehl-Neelsen's and Ehr- 



lich's solutions but is much more 



readily decolourized than the leprosy 



bacillus. 

 Does not stain by Baumgarten's 



method. 

 The tubercle cells contain only a few 



bacilli. 



Baumgarten's method of staining. Stain for 5 minutes in the cold with 

 aniline-violet, decolourize with the 

 following solution : 



Absolute alcohol, - - 10 c.c. 



Nitric acid, - - - 1 ,. 



Wash in distilled water. Dry. Mount. 



The leprosy bacillus is stained 

 violet : the tubercle bacillus is de- 

 colourized. 



Weil has shown that the leprosy 

 bacillus only stains with Ziehl-Neel- 

 sen's and Baumgarten's methods 

 when taken from young nodules. 

 In lesions undergoing resolution these 

 methods as well as Gram's fail to 

 stain the bacillus. 



When stained, the leprosy bacillus 

 is often granular and its protoplasm 

 contains irregular vacuoles. The ends 



are often swollen and Stain easily , FIG. 214 Section through a leprous nodule in the 

 , , . v larynx. Carbol-fuchsm and methylene blue. (Oc. 



by some authors these swellings are 2, obj. ^th, Zeiss.) 

 regarded as spores. 



Jamamoto's stain. By staining in the manner now to be described Jama- 



