8o2 



Favus 



The organism can be studied by extracting a hair and examining 

 it in KOH (40 per cent.) or NaOH (20 per cent.), solution or by 

 teasing a scutulum in the same medium, and examining with a low 

 power. Sections of the skin may also be made when possible. 



The fungus resolves itself into mycelial threads, and spores. The 



A B 



Fig. 325. — Favus. Hairs of a child infected with Achorion schonleinii. A, 

 Magnified 260 diameters; B, 75 diameters. The large rounded bodies are drop- 

 lets of air which always appear after treatment with 40 per cent, potash solution. 

 The linear threads are the fungi. Some are without spores, others contain rows 

 of spores (Sabouraud). 



scutulum consists of masses of spores at the center and about the hair, 

 with mycelia containing spores at the edges. From the mycelium, 

 hypha are given off, the ends being knobbed or clavate. 



The mycelial threads are highly refractile, contain granular proto- 

 plasm, and are of varying thickness. Sometimes the terminal 



