FILAMENTOUS AND BUDDING FUNGI. 347 



the trichophyton tonsurans closely resembles the favus- 

 fungus. The two are, however, not entirely alike. Lique- 

 faction of gelatin takes place much more quickly with 

 the trichophyton, and the deposits are much greater, than 

 with the achorion. At a depth the trichophyton also 

 develops a yellow color in growth. 



For microscopic demonstration of the trichophyton the 

 epidermic scales, removed with a sharp curet, or the epilated 

 hairs, are treated with potassium hydroxid, preferably after 

 previous treatment with chloroform and ether for the re- 

 moval of fat. 



Pityriasis Versicolor. The cause of pityriasis is the 

 microsporon furfur (first described by Eichstedt, in 1846), 



Fig. 80. Microsporon minutissimum ; X 1000 (after Riehl). 



a fungus resembling the favus-fungus and the trichophyton, 

 and, likewise, an oidium. The fungous masses, which are 

 at once recognizable in the horny lamella, removed by 

 means of the finger-nail or .a sharp curet and mixed with 

 six per cent, potassium hydroxid upon a glass slide, consist 

 of unusually large and uniform conidia, which form regularly 

 distributed masses, each of thirty or more, and of slightly 

 ramified, short mycelia, which connect the conidial masses 

 with one another. 



The contagiousness of pityriasis is exceedingly slight. 

 The microsporon obviously requires a quite special predis- 

 position on the part of the skin. It is often found in tuber- 



