CHAPTEE XIX. 

 BACILLUS LEPR^B. 



Introduction. 



Section I. Attempts to reproduce the disease experimentally, p. 348. 



Section II. Morphology, p. 350. 



Section III. Serum -therapy, p. 353. 



Section IV. : Detection and identification of the leprosy bacillus, p. 354. 



LEPROSY, the cause of which is a bacillus discovered by Hansen, is a con- 

 tagious disease peculiar to man : the lower animals are never infected. A 

 disease apparently very similar to human leprosy has however been described 

 as occurring in the rat (Rabinowitsch and others) ; it takes the form of 

 ulcers on the skin and swelling of the glands, and the lesions contain very 

 large numbers of bacilli similar to the leprosy bacillus. 1 



[Though there is no definite and absolutely conclusive proof of the setio- 

 logical role of the organism hitherto commonly known as the bacillus leprce 

 there can be no reasonable doubt bat that the parasite is the cause of leprosy. 

 Recent investigations however would seem to afford amply sufficient ground 

 for believing that the organism is not a true bacterium but rather an hypo- 

 mycete belonging to the genus Discomyces (Streptothrix). This being so it 

 would be more exact to supersede its present designation by the name pro- 

 posed by Deycke : Streptothrix leproides. These researches are also of interest 

 in that they afford botanical evidence of the close relationship which has on 

 other evidence been known for long enough to exist between the parasites 

 of leprosy and tuberculosis.] 



SECTION I. ATTEMPTS TO REPRODUCE THE DISEASE 

 EXPERIMENTALLY. 



Most of the attempts made to reproduce the disease experimentally by 

 inoculating the bacillus have failed. 



In man, Arning is said to have succeeded in inoculating with leprosy the condemned 

 criminal Keanu, but in this case the hypothesis of a spontaneously contracted 

 infection may be pleaded : the same objection may be raised against two or three 

 other cases in which leprosy is said to have been successfully transmitted by inocula- 

 tion. Against these experiments of doubtful validity must be placed the very 

 numerous unsuccessful attempts made by a number of different observers. 



[* This disease is endemic in England, on the Continent, in Australia, in America, and 

 in Japan.] 





