Pathogenesis 701 



"The chromogenic property of lepra cultures is a constant and characteristic 

 feature of the rapidly growing strains. The color varies in the degree of intensity 

 depending upon the medium employed. If glycerinated agar (without peptone) 

 is used, the colonies are faint lemon, while on inspissated blood-serum they are 

 deep orange. It is noteworthy that the growth in the tissues and in the first 

 dozen or so generations on artificial media is entirely without pigment." 



Although each of the workers upon leprosy has begun by asserting 

 that he had certainly cultivated the specific organism, a time comes 

 when a more extended acquaintance with the bacteriology of the 

 disease seems to cause him to doubt the results of his own work. 

 This is particularly true of this work of Duval, which was prosecuted 

 with enthusiasm, carried conviction with it, and then was partially 

 repudiated by its author, for in the discussion before the iyth Inter- 

 national Medical Congress in London in 1913, Duval* is reported as 

 saying that "he knew less of the bacteriology of leprosy now than he 

 did some four years ago. He had made several mistakes, had 

 stated openly that he had cultivated the leprosy bacillus, but now 

 admitted frankly that he was mistaken." 



The interesting question that awaits settlement now seems to be, if 

 these bacilli, and specially the bacillus of Duval, are not Bacillus 

 leprae, what are they? What relation do they bear to leprosy? 



Pathogenesis. Melcher and Ortmann* introduced fragments 

 of lepra nodules into the anterior chambers of the eyes of rabbits, 

 and observed the death of the animals after some months, with what 

 they considered to be typical leprous lesions of all the viscera, 

 especially the cecum; but the later careful experiments of Tashirof 

 show that most of the lower animals are entirely insusceptible to 

 infection with the lepra bacillus, and that when they are inoculated 

 the bacilli persistently diminish in numbers and finally disappear. 



NicolleJ found it possible to infect monkeys with material rich 

 in lepra bacilli taken from human beings. The lesions appeared 

 only after an incubation period that was in some cases prolonged 

 from twenty-two to ninety-four days. The lesions persisted but a 

 short time and the monkeys recovered in from thirty to one hundred 

 and fifty days. 



Clegg and Sugai|| found Japanese dancing mice susceptible 

 to infection with leprous material, the micro-organisms not remain- 

 ing localized at the seat of inoculation, but disseminating through- 

 out the animal's body. Their observation has been confirmed by 

 Duval,** who laterft was also able to infect monkeys Macacus 

 rhesus -with pure cultures of the organism and produce the typical 

 disease. 



* "Berliner klin. Wochenschrift," 1885-1886. 



t "Centralbl. f. Bakt. u. Parasitenk," (Originale), March 12, i9O2,xxxi,No. 

 7, p. 276. 



J "Semaine medicale," 1905, No. 10, p. no. 



"Philippine Journal of Science," 1909, rv, 403. 



|] "Lepra," 1909, vm, 203. 



** "Journal of Experimental Medicine," 1910, xn, 649. 

 tflbid., 191 1, xm, 374. 



