468 LEFEBVRE. 



quently, that if the former is not always found in the nonulcerated 

 leprous parts, it is not because the bacillus has made such parts uninhabit- 

 able for it, but simply because Demodex has not always been established 

 there. Lastly, I have found this parasite also in healthy follicles on 

 lepers, where microscopic examination did not show the bacillus of Hansen 

 to be present. 



In brief, Demodex folliculorum appears only in a quarter of the lepers. 

 When present, it is encountered in those parts of the skin already attacked 

 by leprosy, provided the leprous lesions have not as yet seriously dis- 

 organized the tissues. It can also be found in the parts and in the folli- 

 cles free from leprous infection. It is often absent from those parts 

 affected by leprosy, even when this infection is recent. It is to be noted 

 particularly that Demodex folliculorum is never encountered in the skin 

 of the hands and feet, the parts particularly prone to the lesions of leprosy. 



It is evidently difficult to make the above observations harmonize with 

 the hypothesis that Demodex folliculorum is the principal agent trans- 

 ferring infection in leprosy; but the study of the lesions of leprosy 

 suggests another and more important doubt, which must at once have 

 impressed the reader of BorrePs report. The latter was led, as he 

 admits. 11 after his researches on the same subject in cancer, to suspect 

 the infecting action of an acarid in leprosy. However, is there any 

 analogy? • 



The cancers discussed in Borrel's paper are epitheliomatous ; with the 

 exception, perhaps, of cases of metastasis, they are primary lesions in 

 the places where they are found. One can understand that an external 

 parasite can have deposited, at the place itself, the yet unknown virus of 

 cancer. Can the same be said of leprous lesions? Would a leprologist 

 think that the phenomenon of the anassthetic spots, for instance, has 

 its origin in the skin? Certainly not: it is a nervous manifestation. 

 The same must be said of the mutilations and deformations of the 

 extremities which so terribly afflict the unfortunate lepers. They are tro- 

 phoneurotic troubles in the mutilating lesions, paralyzing in the deform- 

 ing ones. Even were it not physiologically evident, the many works which 

 have appeared on the pathologic anatomy of the nervous system of lepers 

 have amply demonstrated this fact. A striking and common symptom in 

 the leprosy is the moniliform transformation of certain nerves of the 

 limbs, for instance, the ulnar and sciatic; these are often found by pal- 

 pation in the hyperesthetic period before the mutilations and the 

 deformations have appeared. 



If we now pass from these important lesions to the ulcers and from 

 the latter to the nodules which preceded them, and then to the simple 

 turgescences which preceded the nodules, the question arises : Is the 

 cause of these phenomena to be sought for in the skin, or in the glandular 



11 Ibid. 125. 



