6 24 APPENDIX. 



of the favus fungi in the stomach and intestine. On 

 the scalp it first appears as a tiny sulphur-yellow 

 disk or scutulum, depressed in the centre like a cup and 

 pierced by a hair. This is the characteristic lesion. The 

 cup-shape is attributed by Unna to growth at the sides 

 proceeding more vigorously than at the centre. 



There is some difference of opinion as to whether 

 there is only one or several varieties of favus fungus. 

 It was suggested by Quincke that there are three dif- 

 ferent species of favus fungus. Later investigations 



FIG. 86. 



Five-months' old colony of favus on peptone maltose agar. Actual size. 



have apparently shown, however, that the achorion 

 Schoenleinii is the only fungus of favus. 



The favus fungus is readily cultivated at the body- 

 temperature, and also at room-temperature, in the or- 

 dinary culture media, as agar, blood-serum, gelatin, 

 bouillon, milk, infusion of malt, eggs, potato, etc. 

 (Fig. 86). The growth develops slowly and shows a 

 preference to grow beneath the surface of the medium 

 except on potato, upon which it develops on the surface 

 in layers. The characteristic form of growth is that of 

 moss-like projections from a central body. The color 



