234 B ACTERIOLOG Y 



Grawitz, and the fungus fur floats upon the surface as a 

 thick coating, white above and yellow underneath. 



The fungus of favus (Achorion Schoenleinii) . In the scaly 

 accumulations from persons suffering from 

 favus, Schonlein discovered a fungus to 

 which the name of Achorion Schcenleinii 

 has been given. The favus crusts or 

 scutula show the mycelium of the organ- 

 ism, which is remarkable for the fact that 

 the fibres grow up perpendicularly from 

 the horny layer. The right angle formed 

 by these fibres with the substratum is 

 characteristic of the scutula of favus, since, 

 in the horny scales permeated by the fungus 

 of pityriasis versicolor or by the Trirho- 

 phyton the fibres of the organism form 

 acute angles, or run parallel with the cells 

 of the horny layer. 



Unna differentiates three varieties of 

 favus fungus the Achorion euthythrix, with 

 straight fibres and abundant formation of 

 spores ; the Achorion dicroon, with forking 

 hyphae ; and the Achorion atacton, the hypha3 

 of which run an irregular course and pos- 

 sess peculiar knotty ramifications and many 

 sharp angles. The first forms voluminous 

 greyish-yellow scutula (favus griseus), the 

 second sulphur-yellow scutula, which are 

 slow in developing (favus sulphur eus tar- 

 dus), and the third sulphur-yellow scutula 

 also, which form more quickly (favus sul- 

 IG. 88. SURFACE vlmreus cclereus). Unna used for cultiva- 



CULTURE OP THE " 



ON : SERUM cS ti n a medium composed of 4 per cent, of 

 ?u>. D (Afte N r E piaut!) agar, 1 per cent, of peptone, and 5 per cent. 



