2/0 



LEPROSY. 



size as tubercle bacilli, which they also resemble both in appear- 

 ance and in staining reaction. They are straight or slightly 

 curved, and usually occur singly, or two may be attached end 

 to end ; but they do not form chains. When stained they may 

 have a uniform appearance, or the protoplasm may be frag- 

 mented, so that 

 they appear like 

 short rows of 

 cocci. Theyoften 

 appear tapered at 

 one or both ex- 

 tremities ; occa- 

 sionally there is 

 slight club-like 

 swelling. De- 

 generated , and 

 partially broken 

 down forms are 

 also seen. They 

 take up the basic 

 aniline stains 

 rather more read- 



FlG. 97. Superficial part of leprous skin; the cells of the ^ 



granulation tissue appear as dark patches, owing to the deeply bacilli, but in 



stained bacilli in their interior. In the upper part a process of j 

 epithelium is seen. 



Paraffin section; stained with carbol-fuchsin and Bismarck- them deeply a 



brown, X 500. r , . . 



powerful stain, 



such as carbol-fuchsin, is necessary. When stained, they strongly 

 resist decolorising, though they are more easily decolorised than 

 tubercle bacilli. The best method is to stain with carbol-fuchsin 

 as for tubercle bacilli, but to use a weaker solution of sulphuric 

 acid, say 5 per cent, in decolorising ; in the case of films and thin 

 sections, decolorising with such a solution for fifteen seconds is 

 usually sufficient. Thereafter the tissues are coloured by a con- 

 trast stain, such as a watery solution of methylene-blue(W^ p. 104). 

 The bacilli are also readily stained by Gram's method. Regard- 

 ing the presence of spores practically nothing is known, though 

 some of the unstained or stained points may be of this nature. 

 We have, however, no means of testing their powers of resist- 

 ance. Leprosy bacilli are non-motile. 



