830 Favus 



isms than as a single one. Indeed, Quincke has described 

 three species, though they are not yet generally accepted. 



The organism can be studied by extracting a hair and exam- 

 ining it in KOH or NaOH solution (20 per cent.), 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 scutulum consists of masses of spores at the center and 

 about the hair, with mycelia containing spores at the edges. 



Fig. 282. Achorion schonleinii. Fig. 283. Achorion schonleinii. 



Four weeks' old culture upon beer- Pure culture, four weeks old, on 



wort agar-agar (Kolle and Wasser- beerwort agar-agar (Kolle and 



mann). Wassermann). 



From the mycelium hypha are given off, the ends being 

 knobbed or clavate. 



The mycelial threads are highly refractile, contain granular 

 protoplasm, and are of varying thickness. Sometimes the 

 terminal hypha are simple, sometimes they fork, the ends are 

 .always clavate. The hypha give off buds at right angles 

 along their course. 



The spores are oval, doubly contoured, as a rule, but may be 

 round or pointed and more or less polyhedral. They measure 

 3 to 8 ft in length and 3 to 4 f* in breadth. They form the 

 great central mass of the scutulum, which is the oldest part. 

 Together with them one finds a number of detritus granules, 

 fat-droplets, and occasional swollen epidermal cells. 



Cultivation. The cultivation of the achorion is quite 

 easy if care be used, for the central part qf each scutulum 

 contains pure cultures of the organism. The best method is 



