BACILLUS OF LEPROSY. 261 



considerable size, the margins of which show a somewhat 

 livid congestion. Later, these patches become pale in the 

 central parts, and the periphery becomes pigmented. There 

 then follow remarkable series of trophic disturbances in 

 which the skin, muscles, and bones are especially involved. 

 The skin often becomes atrophied, parchment-like, and 

 anaesthetic ; frequently pemphigoid bullae or other skin 

 eruptions occur. The bones become atrophied, and, 

 owing to the irregular affection of the muscles, great dis- 

 tortion of the extremities may result. Partly owing to 

 injury to which the feet and arms are liable from their 

 anaesthetic condition, and partly owing to trophic disturb- 

 ances, necrosis and separation of parts are liable to occur. 

 In this way great distortion results. The lesions in the 

 nerves are of the same nature as those described above, 

 that is, they are the result of a chronic inflammatory process, 

 but the granulation tissue is less in amount, and has a 

 greater tendency to undergo cicatricial contraction. This 

 is to be associated with the fact that the bacilli are present 

 in fewer numbers. 



Bacillus of Leprosy. This bacillus was first observed 

 in leprous tissues by Hansen in 1871, and was the subject 

 of several communications by him in 1874 and later. 

 Further researches, first by Neisser in 1879, and afterwards 

 by observers in various parts of the world, agreed in their 

 main results, and confirmed the accuracy of Hansen's 

 observations. The bacilli as seen in scrapings of ulcerated 

 leprous nodules, or in sections, have the following characters. 

 They are thin rods of practically the same size as tubercle 

 bacilli, which they also resemble both in appearance 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 

 fragmented, so that they appear like short rows of cocci. 

 They often appear tapered at one or both extremities ; 

 occasionally there is slight club-like swelling. Degenerated 

 and partially broken down forms are also seen. They take 



