420 HIGHER HYPHOMYCETES AS THE CAUSE OF DISEASE 



about 30 C. It liquefies gelatin, on which it forms a white, dusty cover 

 which is difficult to break up. On potatoes a folded felty, sometimes 

 white, at other times yellowish, reddish, or dark membrane is formed. 

 If examined microscopically the growth shows a septate, colorless 

 mycelium, and round or oval chlamydospores. Different cultures 

 vary considerably in certain features, so that a number of varieties 

 have been distinguished, such as Trichophyton megalosporon (large 

 spores), Trichophyton microsporon (small spores), and several 

 others. Spores in pure cultures are generally formed within the hyphen 

 as chlamydospores. In the skin and hairs they are formed by the 

 breaking up of the filaments into segments (gemmse). 



FIG. 167 



Portion of a hair showing the Microsporon Audouini. (From a photomicrograph.) 



One of the varieties of the Trychophyton tonsurans has been 

 called Microsporon Audouini, and two of its subvarieties, the equinum 

 and the caninum, have been found, respectively, in horses and dogs. 

 Certain authors, however, claim that the different varieties of Tricho- 

 phyton tonsurans are really a single species producing practically 

 the same infection, only somewhat modified as to the species of 

 animal infected. The mode of infection consists in that the mould 

 first penetrate into the hair roots, where they multiply and surround 

 the hair with a complete mantle and then enter into its interior. 

 Trichophyton tonsurans infections have also been observed a few 

 times in domestic birds. 



Achorion Schonleinii. This mould is the cause of the disease 

 known as favus, dermatomycosis achorina, tinea favosa,"Wabengrind" 

 or "Erbgrind der Saugethiere" (German). It occurs in man, mice, 

 rats, cats, dogs, and rabbits. A few cases which were described as 

 appearing in horses and cattle were probably trichophyton infections. 

 Favus infection is characterized by the formation of scaly crusts, 

 which are depressed in the centre and sulphur yellow, at least in the 

 interior, where the color has not been changed by external influences. 





