BACILLUS OF LEPROSY 269 



all situations the change is of the same nature, a chronic 

 inflammatory condition attended by abundant formation of 

 granulation tissue, nodular or diffuse in its arrangement. In this 

 tissue a large proportion of the cells are of rounded or oval shape, 

 like hyaline leucocytes ; a number of these may be of compara- 

 tively large size, and may show vacuolation of their protoplasm 

 and a vesicular type of nucleus. These are often known as 

 " lepra-cells." Amongst the cellular elements there is a varying 

 amount of stroma, which in the earlier lesions is scanty and 

 delicate, but in the older lesions may be very dense. Periarteritis 

 is a common change, and very frequently the superficial nerves 

 become involved in the nodules and undergo atrophy. The 

 tissue in the leprous lesions is comparatively vascular, at least 

 when young, and, unlike tubercular lesions, never shows caseation. 

 Some of the lepra cells may contain several nuclei, but we do 

 not meet with cells resembling in their appearance tubercle 

 giant-cells, nor does an arrangement like that in tubercle follicles 

 occur. 



In the anaesthetic form the lesion of the nerves is the out- 

 standing feature. These are the seat of diffuse infiltrations 

 which lead to the destruction of the nerve fibres. In the earlier 

 stages, in which the chief symptoms are pains along the nerves, 

 there occur patches on the skin, often of 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, parch- 

 ment-like, and anaesthetic ; frequently pemphigoid bullse or other 

 skin eruptions occur. Partly owing to injury to which the feet 

 and arms are liable from their anaesthetic condition, and partly 

 owing to trophic disturbances, 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 scantier, 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 



