154 V^aUTABLE PARASITES. 



the cause of "Porrigo decalvans;" no matter whether the hair 

 breaks off at last in consequence of the interrupted nourishment, 

 or because the elements necessary for the development of the 

 hair are absorbed by the fungus. The light gray crusts which 

 cover the places which have been. deprived of their hair consist 

 of the parasite mixed with a certain quantity of epithelial cells. 

 Its contagious nature is explained by these facts, and the con- 

 tagion of " Porrigo decalvans," is nothing more nor less than 

 the spores of Microsporon Audouini. 



Gruby discovered this fungus in 1843; Robin found it on a 

 child ; Cazenave denies it, and regards it as the result of an 

 optical deception. Bazin found the disease everywhere on bodies 

 covered with hair, and recommends epilation and washing with 

 corrosive sublimate, acetate of copper, or the preparations of tar. 

 If epilation is resorted to, it is necessary to seize the hair below 

 the diseased spot, as far as possible, at the edge of the skin. 



Droste lately noticed in the ' Deutschen Klinik/ 3854, No. 

 39, a case of porrigo, described in English journals, of a general 

 absence of every hair of the body, with the exception of some 

 hair on the back part of the ear. If the cure of this case was 

 successful, it was, no doubt, nature's work, and not procured by 

 the above-mentioned remedies. The disease disappeared when 

 all the parts subject to this disease had disappeared, that is, when 

 every hair had fallen off. This general and rapid epilation, 

 caused naturally, remains, however, very remarkable. It is much 

 to be regretted, and must be repeated over again, that similar 

 cases are lost for exact science, as long as the microscope is not 

 more frequently employed in the examination of skin-diseases. 

 It is here more especially, where its practical use would become 

 most evident, and where the labour employed on it would soon 

 find its ample reward. I am, therefore, unable to decide whether 

 the case of which Droste speaks exhibited this class of fungi. 



Literature. Gruby, ' Compt. rend./ &c., 1843, xvii, p. 301, 

 and 1844, p. 585; Cazenave, 'Traite des Maladies du Cuir chevelu/ 

 1850, p. 197; Bazin, 1 c., 1853, p. 40; Malmsten, Muller's 

 'Archiv/ 1848, p. 7; Robin, 1. c., p. 426 427. 



