LEPROSY. 245 



From the whole nature of the symptoms, and from the 

 course of the disease, it was long considered to be a disease 

 somewhat similar to tuberculosis, and the discovery, by 

 Armauer Hansen, in 1880, of a specific leprosy bacillus, 

 which was found to be present in enormous numbers in the 

 lymph channels of the skin in cases of leprosy, paved the 

 way, for the reception of Koch's discovery of the tubercle 

 bacillus. 



It was for some time supposed that the tubercular and 

 anaesthetic forms of leprosy were different in their origin, and 

 that they might possibly be due to the action of different 

 bacilli, although it was of course known that in some cases 

 there was a kind of mixed leprosy. The fact that the two 

 diseases were the same was, however, strongly accentuated 

 when it became evident that the same kind of bacillus was 

 found in all three forms of the disease the tubercular, the 

 anaesthetic, and the mixed. 



Before a description of the morphological characters of the 

 bacillus is given, the characters of the various forms of the 

 disease may be briefly indicated, in order that the patho- 

 logical changes produced by the bacillus may be more fully 

 understood, and that the bacilli may be followed and localized 

 in the tissues. In tubercular leprosy there usually appear 

 small irregular spots, sometimes brown, sometimes some- 

 what purple. These spots occur on the face or on the 

 limbs ; they gradually project so as to form more or less 

 marked tubercles, which vary very considerably in size. 

 There is irregular thickening of the tissues under the skin 

 of the face, which gives rise to a most curious facial expres- 

 sion, the patient appearing melancholy or jubilant according 

 to the folds affected ; the tissues about the various orifices 

 of the face, mouth, eyes, nostrils become swollen, and are 

 often studded with tubercles, the lower lip becomes heavy 

 and hangs down in a curious fashion ; these alterations giving 

 the face what is described as the " leonine ' appearance. 

 Sometimes sensibility is interfered with, or it may be alto- 

 gether abolished. These tubercles are not confined to the 

 tissues immediately under the skin ; they may also be found 

 in the submucous tissue of the mouth, larynx, and pharynx; 

 and small nodules may even be met with especially where 

 the swelling is marked around the eye in the soft tissue of 

 the eyelids. These nodules frequently ulcerate, especially in 



