692 THE PARASITES OF FAVUS 



Characters of growth. Agar. On agar, a yellow brown wrinkled layer is 

 formed with a depression in the centre like the cup-shaped depression on the 

 scalp. 



Sabouraud's medium is better than ordinary agar. 



Granulated peptone (Chassaing), - 2 grams. 



Pure anhydrous glycerin, ... 4 ,, 



Agar, 1*6 



Distilled water, - - 100 c.c. 



Potato. A dry, raised, mammillated layer brownish-grey or brown in 

 colour appears about the fourth to the fifteenth day. The potato turns 

 brown. 



Broth. Growth takes the form of a large spreading colony floating on 

 the surface of the medium. The colony has the same appearance as a growth 

 on agar. 



B. The parasites of favus in the lower animals. 



The parasites found in favus in some of the lower animals are related to, but are 

 not identical with, Achorion schcenleini. 



1. Achorion quinckeanum. Favus in mice is caused by Achorion quinckeanum. 

 In the lesions, the parasite forms mycelial filaments of varying length consisting 

 of rectangular or ovoid cells : the filaments break up into short rectangular bodies 

 which constitute the spores. The parasite grows readily at 35 C. on media con- 

 taining glucose or glycerin. It is pathogenic to guinea-pigs and mice and gives 

 rise to scutula when a week- old culture on agar is inoculated on a lightly abraded 

 area of the skin. 



2. Achorion arloingi. A. arloingi was found in a case of a ringworm-like disease 

 by D6sir de Fortunet. It is pathogenic to mice, rabbits and man. 



3. Oospora canina. Favus in dogs is due to a related fungus, Oospora canina 

 (Costantin and Sabrazes). 



SECTION V. THE GENUS LOPHOPHYTON. 

 Lophophyton gallinse. 



Favus in fowls is caused by Lophophyton (Epidermophyton) gallincB (Megnin). 

 [This parasite can be made to infect man in which case it does not produce 

 the cup so characteristic of favus but large erythematous patches.] 



SECTION VI. MICRO-ORGANISMS IN ALOPECIA AREATA, 



A large number of cases of alopecia are now acknowledged not to be of a parasitic 

 nature. In ordinary alopecia numerous observers including the author have con- 

 sistently failed to detect any specific infecting agent. Whatever the aetiology of 

 alopecia, and there is probably more than one cause (tropho-neurotic alopecia, etc.), 

 it must be admitted that micro-organisms rarely play any part in the causation of 

 the disease. 



It is possible that some cases of pseudo- alopecia are due to the coccus described 

 by Vaillard and Vincent. 



SECTION VII. THE BACILLUS OF SEBORRHCEA OLEOSA. 



[The micro-bacillus of the "peladic utricle" in alopecia areata.~] 



Sabouraud described a bacillus as being present in seborrhoea oleosa. The patho- 

 genic role of the organism is not yet fully understood, but it does not seem to play 

 the part in the causation of alopecia which he thought he was justified in attributing 

 to it. 



