RESEARCHES ON ACARIDS AMONG LEPERS. 467 



thev will constitute a second unfavorable conclusion to Borrel's hypothesis, 

 the first being that drawn from the absence of Demodex among young 

 children. 



It seems, in fact, that if Demodex were either the principal or the 

 only agent for the propagation of leprosy, this parasite would be found 

 in all, or. at least, in the greater number of lepers. However, this 

 objection thus formulated would be too absolute, as the reply might be 

 made that the infecting parasite would necessarily exist in the skin of 

 the leper at the time of infection, but might well disappear later during 

 the evolution of the disease. Demodex folliculorum is not a migratory 

 parasite, it never changes its home: the same follicle is its cradle and 

 its grave. However, it might be that the leprous lesions, with their 

 dreadful ulcerations, render the follicle uninhabitable, or possibly firing 

 about the death of the parasite. This must be the case once the ulcera- 

 tion has appeared. I have never found Demodex in an ulcer however 

 recently it has been opened. 



For this reason I pursued my investigations principally on the sebaceous 

 glands from parts of the body which either were healthy, or on those 

 (especially the nose and ears) which were only beginning to show 

 symptoms of leprosy, and also on the sound skin which covered the be- 

 ginning leprous nodules. From this long series of examinations, which 

 includes several hundreds of sebaceous glands, I obtained the following 

 results. 



As already stated, Demodex folliculorum was not of frequent occur- 

 rence, it being found only on about a quarter of the lepers. It was not 

 more frequent in the follicles of the leprous parts on the face than in 

 the corresponding healthy parts. It was never encountered anywhere in 

 the body except in the glands of the face or ears, either upon direct 

 examination of the contents of the sebaceous glands or of microtomic 

 sections of young nodules excised either from the living or the dead ; and, 

 moreover, it was never found in the normal skin of the hands and feet. 

 either of health}' persons or of lepers. 



The leprous spots that are met with in anassthetic leprosy in all 

 infected parts of the body including the face, for example, the livid or 

 colored spots, and those invisible areas recognizable only by their anaasthe- 

 sia, are free from Demodex. There are even places where the sebaceous 

 glands are half atrophied, shriveled, small, and performing their func- 

 tions improperly. 



On the other hand, I have sometimes encountered Demodex follicu- 

 lorum in the glands of the nose, ears, and chin, when these parts were 

 already manifestly leprous. In such cases they were often found together 

 with the bacillus of Hansen. I also have seen Demodex folliculorum, 

 together with the Hansen bacillus, in the enormous follicles of acne 

 molluseum in the case mentioned above. " This is noteworthy, because 

 it shows that Demodex and the bacillus can live together, and conse- 



