On Bacterium decalvans. 



247 



" On Bacterium decalvans : an Organism associated with the De- 

 struction of the Hair in Alopecia areata." By George 

 Thin, M.D. Communicated by Professor Huxley, Sec. R.S. 

 Received February 19, 1881. Read March 3. 



[Plate 3.] 



Although Gruby,* in the year 1843, announced that the affection of 

 the hairy scalp known as alopecia areata (area celsi) is caused by a 

 fungus, the parasitic theory of the disease has met with comparatively 

 little support. If the patients on whom Gruby made his observations 

 really suffered from this disease and not from ringworm, which in 

 some of its forms is apt to be mistaken for it, this uncertainty is very 

 remarkable. The fungus, if it exists, should not be difficult of 

 observation, since it is described in his paper as consisting of a sheath 

 of mycelium and spores which accompanies the hair to a distance of 

 1 — 3 millims. from the skin. Few competent observers have, how- 

 ever, been able to find a fungus in this disease, and Dr. Michelson, of 

 Konigsberg, in an able historical sketch in a recent number of " Vir- 

 chow's Archiv,"f quotes with approval a statement by Pincus,^ who 

 avers that up to the year 1869 none of the observations which are 

 relied on as confirming Gruby' s observations will stand criticism. The 

 fungus has been sought for chiefly by dermatologists, and in Hebra's 

 text-book of "Skin Diseases,"§ a work of recognised standing, 

 v. Barensprung, Hebra, Wilson, Neumann, Bceck, Duhring, Scheren- 

 berg, and Kaposi are cited as having been unable to find it. The 

 parasitic theory originated by Gruby was noticed less and less by 

 authorities, the disappearance of the hair in patches from a pale un- 

 inflamed skin being attributed to a " tropho -neurosis." 



Latterly, the question of parasitism has been again raised. Malassez|| 

 stated in a paper published in 1874 that he had found a fungus, not 

 in the hairs, but on the surface of the epidermis of the diseased parts. 

 There was no mycelium found, but only spores, of which he described 

 three types : — 



1. Double- contoured spores, sometimes with a bud (bourgeon'), 4 — 5/t 

 in diameter ; 



2. Smaller spores, 2 — 2'5/z. large, single-contoured, some of these 

 also with a bud ; 



3. Yery small, under 2jji sporules, single-contoured and without 

 buds. 



* " Comptes Eendus," 1843, xvii, p. 301. 

 f Yol. lxxx, p. 296. 



X " Ueber Herpes tonsurans u. Area Celsi." " Deutsche Klinik," vol. xxi. 



§ " Lehrbuch der Hautkrankheiten," vol. ii, p. 150. 



|| " Archives de Physiologic Norm, et Patkolog.," 1874. 



VOL. XXXIII. S 



