BACILLUS OF LEPROSY 299 



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 comparatively 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 anesthetic 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 bulke 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, 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 

 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 



