PART IV. 



THE HYPHOMYCETES, OR MOULD FUNGI. 



ACHORION SCHONLEINIL 



This fungus, the cause of favus in man, horses, cattle, dogs, cats, 

 rabbits, and mice, was discovered by Schonlein in 1839. It is found 

 in the so-called favus crusts. According to Unna, there are nine 

 varieties of favus. The disease is most frequently observed on a head 

 possessing hair, although it is also found on skin devoid of hair. It 

 also attacks the nails (Onychomycosis), the parasite being located 

 between the cells of the epidermis and the corium. Kaposi also 

 mentions a case of favus universalis. 



Microscopical Appearances. The mycelium consists of branched 

 radiating hyphae. Some of the hyphae swell at their free ends, 

 becoming club-shaped, while others give off lateral buds containing 

 Krals' so-called yellow bodies, which rupture, allowing their contents to 

 escape as free bodies. When this takes place, moss-like offshoots 

 develop in the form of dense twisted threads. Later, the individual 

 threads break up into cell-like oval structures. 



Biological Characters. To obtain the fungus in pure cultures, 

 the favus crusts are mixed with sterile sillic acid, reduced in a sterile 

 mortar, and plate cultures instituted with the mixture. The growth 

 takes place at both room and incubator temperature on all the nutrient 

 media, usually under the surface, because only a few air-hyphae are 

 formed. In the beginning, from the periphery of the white growth, 

 which later becomes yellow, fine radiating offshoots penetrate the body 

 of the substratum of the medium. (See Photomicrograph, Fig. 86.) 



On Gelatine Plates, white, stellate, quickly liquefying colonies, with 

 thick centres. 



In Gelatine Stab Cultures a coating forms on the surface, the under- 

 growth being of a yellow colour. 



On Agar a puckered whitish coating, the under surface being yellow. 

 (See Photograph, Fig. 85.) 



