LEPROSY BA GILL US. 315 



culosis and the bacillus of leprosy are both very retentive 

 of their color, even after treatment with acids and 

 alcohol. If, then, we treat the preparation, stained with 

 carbolfuchsin, with sulphuric acid, the syphilis bacillus 

 becomes almost at once decolorized. If it is not imme- 

 diately decolorized, treat with alcohol; if it is then 

 decolorized, it is the smegma bacillus. If it is still 

 not decolorized, it is either the leprosy or the tubercle 

 bacillus. 



By these methods the differential diagnosis can usually 

 be made. In all investigations of importance, however, 

 animal inoculations should also be made, as by this 

 means alone can a positive diagnosis from tuberculosis 

 be established. Especial care should be observed in 

 the examination of syphilitic ulcers of the genital re- 

 gion, as in this situation the smegma bacilli are almost 

 always present. 



LEPROSY BACILLUS. 



The bacillus of leprosy was discovered by Hansen 

 and Neisser (1879) in the leprous tubercles of persons 

 afflicted with the disease. This discovery was confirmed 

 by many subsequent observers. 



Morphology. Small, slender rods resembling the 

 tubercle bacilli in form, but somewhat shorter and 

 not so frequently curved. The rods have pointed ends, 

 and in stained preparations unstained spaces, similar to 

 those observed in the tubercle bacillus, are seen. They 

 stain readily with the aniline colors and also by Gram's 

 method. Although differing from the tubercle bacillus 

 in the ease with which they take up the ordinary aniline 

 dyes, they behave like tubercle bacilli in retaining their 



