248 



SPECIFIC MICRO-ORGANISMS 



successfully inoculated his skin with these cultures. He named 

 the organism Achorion schoenleinii. In the lesion of favus the 

 threads of the fungus are found growing in the horny layer of the 

 epidermis, usually about a hair, and giving rise to a dry, circular, 

 yellow crust with depressed center, the " Scutulum" By macerat- 

 ing this crust in 50 per cent antiformin the elements of the mold 

 are made clearly visible under the microscope. In the center of 

 the lesion are doubly contoured oval or rectangular conidia, 3 



Pig. 100. — Typical scutulum of favus in a mouse. (After Plaut.) 



to Sjn by 3 to 4n, single and in chains. The mycelial threads 

 are indistinguishable in the center, but are seen at the periphery 

 as tubes of very irregular width, refractive with granular proto- 

 plasm, often branched or knobbed at the end. The scutulum 

 in its interior is a pure culture of the mold, entirely free from other 

 organisms. The mold also grows in the interior of the hair shaft, 

 and by macerating the hair in alkali the fungus may be demon- 

 strated microscopically. 



Cultures may be obtained upon various media. Plaut recom- 

 mends a medium containing pepton i to 2 per cent, glycerin 



