758 Favus 



two principal varieties: (i) The waxy type — -a yellowish mass of a 

 waxy character with radiating folds and a central elevation. As a 

 rule no aerial hyphae, but occasionally short aerial hypha. 



(2) The downy type — this forms a white disk with a velvety or 

 plush-like covering of white aerial hypha. Sometimes instead of 

 white the color is yellowish or reddish. A marked dimple with a 

 smaller elevation usually occurs in the middle, and there may be 

 radial folds. 



Pathogenesis. — The micro-organism is pathogenic for mice, 

 rabbits, cats, dogs, hens, and nien, in all of whom typical scutula 

 form. Scutulum formation has not been observed in guinea-pigs. 

 The disease readily spreads from animal to animal by direct contact 

 and by indirect contact by the use of combs, hair-brushes, and simi- 

 lar objects. On account of its chronicity, its obstinacy, its disfig- 

 urement, and its transmissibility it is a dangerous disease, and one 

 that requires prompt isolation of the patient and the utmost care for 

 the prevention of contagion. 



