l6o MEDICAL BACTERIOLOGY 



cool surface to rapidly reduce the temperature, then examined. The micro- 

 scopic appearance of the most common forms is as follows : 



Trichophyton megalosporum endothrix. Affected hairs are swollen and 

 rilled with spores arranged in chains. These spores are 5 to 6 M in diameter. 



Trichophyton microides ectothrix, spores no larger than tricophyton megalo- 

 sporon endothrix, are observed both within and surrounding hairs. 



Trichophyton megasporon ectothrix, spores from 8 to 15 //, in diameter, are 

 found both within and surrounding the hairs. 



Microsporon audouini, affected hairs are covered with irregularly arranged 

 masses of spores. These spores are round and measure from i to 3 /j in 

 diameter. They never penetrate the hair. 



MICROSPORON FURFUR 



Microsporon furfur is the cause of tinea versicolor (pityriasis versicolor), a 

 skin disease showing a yellow macular eruption on the upper part of the trunk. 



Diagnosis. Scrape the lesions with a knife or glass, place the scrapings in 

 a drop of potassium hydrate solution on a slide and cover with a cover glass. 



Collections of filaments and spores are observed between the epithelial cells. 



The filaments are 3 to 4 /* in diameter, septate and branched. 



The spores occur singly and in irregular masses; they are spherical, 3 to 4 /tin 

 diameter and are encapsulated. 



