688 THE PARASITES OF RINGWORM 



[This uncertainty arises because it is doubtful whether the organs of fructification 

 seen by Tribondeau, Jeanselme, and Wehmer are accidental contaminations due to a 

 saprophyte growing symbiotically with the true parasite of the disease or whether 

 the filaments and fructifications are all part of one and the same parasite. The 

 description of the parasite as seen in the lesions is given at p. 700. 



[Nieuwenhuis has cultivated a parasite in every way resembling a Tricophyton 

 by sowing epidermal scales freshly taken from the lesions, and with these cultures 

 has succeeded in reproducing the disease in man. Tribondeau with cultures of his 

 Aspergillus has infected himself with the disease. 



[Castellani has also been able to cultivate the Endodermophyton concentricum and 

 an allied species E. indicum and in both instances has reproduced the disease by 

 experimental inoculation of his cultures. 



[The aetiology of tinea imbricata must therefore be considered undetermined : 

 further research is necessary to definitely solve the question (Brumpt).] 



SECTION II. THE GENUS EPIDERMOPHYTON. 

 Epidermophyton cruris. 



[Syn. Epidermophyton inguinale. ] 



Ringworm in the groin [Eczema marginatum, Tinea marginata> Tinea 

 cruris] is due to a parasite, described by Sabouraud, Epidermophyton cruris, 1 

 closely resembling the other ringworm parasites in many of its characteristics, 

 but differing from them in that it always remains limited to the stratum 

 corneum of the epidermis and never attacks the hair. 



Epidermophyton cruris forms a network of mycelium filaments composed 

 of quadrangular cells arranged end to end growing horizontally between the 

 cells of the stratum corneum. 



The parasite grows on Sabouraud's medium but produces no racemes of 

 spores. Attempts to experimentally infect man and the lower animals 

 have not been successful. 



[SECTION III. THE GENUS MICROSPORUM.] 

 1. Microsporum audouini. 



Microsporum audouini was first seen by Griiby, who found it in an anomalous 

 parasitic disease of the hair which he called prurigo decalvans (bald ringworm), 

 and which was subsequently confused with alopecia and tricophytosis. 



Sabouraud, however, cleared up the difficulty and showed that the disease which 

 he calls teigne tondante rebelle or teigne tondante of Griiby bald ringworm [and 

 which is characterized by the presence of smooth bare spots of greater or less extent] 

 is caused by infection with a microsporum. The parasite is properly designated Micro- 

 sporum audouini, and not Tricophyton microsporum as Sabouraud originally described 

 it, since it differs from the Tricophyta both in its appearance in the affected hairs 

 and in its mode of growth in artificial culture (Bodin). 



[Microsporum audouini is the cause of 90 per cent, of juvenile ringworm 

 in London (Malcolm Morris).] It does not grow on the glabrous skin, but 

 only on the hair. Hairs infected with M. audouini have a characteristic 

 appearance : they break off 6 or 7 mm. from the skin, have lost their colour, 

 are very thin, and are covered with the parasite which imparts to them a 

 smooth, grey appearance as though they were sprinkled with a blue dust. 



Bodin has described two varieties of Microsporum audouini. 



M. audouini var. cam's is* the cause of a ringworm in the dog ; it is transmissible 

 to man and produces a condition similar to the bald ringworm of Griiby ; inocu- 

 lated on the guinea-pig it leads to a ringworm which resolves spontaneously in a 

 few weeks. 



t 1 E. cruris is the cause, in some cases, at least, of Dhobie itch. ] 



