398 THE ETIOLOGY OF TROPICAL DISEASES 



produces anaesthesia, paralysis, and what are called "trophic" 

 changes. Not infrequently patches occur on the skin, which appear 

 like parchment, owing to this trophic change. Bullae may arise. 

 When the tissue change is radical or far advanced, considerable 

 distortion may result. The mixed variety of leprosy, as its name 

 implies, is a mixture of the two other forms. 



The BacteFiolog"y of Leprosy.— The B. leprm was discovered 

 by Hansen in 1874. He found it in the lepra cells in the skin, 

 lymph glands, liver, spleen, and thickened parts of the nerves. It 

 is common in the discharge from the wounds of lepers. It is 

 conveyed in the body by the lymph stream, and has rarely been 

 isolated from the blood (Kobner). 



The bacillus is present in enormous numbers in the skin and 

 tissues, and has a form very similar indeed to B. tuberculosis. It is 

 a straight rod, and showing with some staining methods . marked 

 beading, but with others no beading at all. It measures 4 ^ long 

 and 1 /u broad. Young leprosy bacilli are said to be motile, but old 

 ones are not. Neisser has maintained that the bacillus possesses a 

 capsule and spores. The latter have not been seen, but Neisser holds 

 that this is the form in which the bacillus gains entrance to the 

 body. There is a characteristic which fortunately aids us in the 

 diagnosis of this disease in the tissues, and that is the arrangement 

 of the bacilli, which are rarely scattered or isolated, as in tubercle, 

 but gathered together in clumps and colonies. The bacilli occur 

 for the most part inside the round cells, but they are also found free 

 in the lymphatics, inside connective tissue cells, and in the walls of 

 blood-vessels. A few may often be found in the hair follicles or 

 glands of the skin, or even in the epithelium. The bacilli also occur 

 in the lymphatic glands and in the internal organs. The brain and 

 spinal cord are almost always exempt. But recent research has 

 made it evident that the distribution in the tissues may be more 

 widespread than was formerly supposed. Bordoni - Uffreduzzi, 

 Carrasquilla (1899) and Campana, claim to have isolated the bacillus 

 and grown it on artificial media, the two former aerobically on 

 peptone-glycerine blood serum, at 37° C, the latter anaerobically. 

 Other workers have been unable to obtain successful results. Culti- 

 vated bacteria from the organs of lepers, described rather later by 

 Babes, and still more recently by Czaplewski, differ from the genuine 

 bacillus of leprosy in their incomplete resistance to acids. Both 

 authors maintain that the bacteria cultivated by them resemble the 

 bacilli of diphtheria. In any case it is very doubtful whether these 

 bacteria cultivated from leprosy are the genuine Bacillus leprae. 

 Hence it is not possible to study the bacteriology of leprosy at all 

 completely ; inoculation experiments also have not proved successful. 

 Nevertheless there is little doubt that leprosy is a bacterial disease 



