HYPHOMYCETES 



643 



The achorion grows best upon acid agar at a temperature of 

 37.5 C. Growth appears within from forty-eight hours to three days 

 as yellowish disks, which occasionally may be slightly furred with 

 aerial hyphae. 



Ringworm (Trichophyton tonsurans) . -Ringworm, Tinea circinata, 

 or Herpes tonsurans, is a contagious disease of the skin and hair, occur- 

 ring most frequently in children and appearing upon the haired por- 

 tions of the body as well as upon free skin. It is characterized by the 

 formation of circular scaly patches, within which the hairs fall out. 



The disease is caused by several species of the trichophyton, a genus 

 of hyphomycetes. These microorganisms were first recognized as in- 

 citants of the disease by Gruby x in 1841, and were studied later by 

 Sabouraud. 2 The fungi consist of finely interlaced narrow septate 

 mycelia, within which characteristic 

 swellings appear. From these swell- 

 ings, chlamydospores develop. Hyphae, 

 both aerial and deep, grow out of the 

 mycelial threads, on the ends of which 

 ascospores may develop. In the dis- 

 eased skin, the fungi grow within the 

 hair sheath, causing an area of second- 

 ary inflammation about the base of the 

 hair. The infection probably begins 

 first in the epidermis surrounding the 

 hairs, from which it then spreads into 

 the hair bulb and thence grows up into 

 the substance of the hair in which 

 mycelial threads and spores develop in 

 large numbers. The demonstration of 

 the microorganisms from a case can easily be accomplished by epilating 

 an affected hair, making sure that the hair bulb has been removed. 

 This is then immersed under a cover-slip in a drop of sodium hydrate 

 or potassium hydrate solution and examined under the microscope. In 

 this way enormous numbers of short mycelial threads and spores may 

 be seen to lie within the bulb. Many varieties of these fungi have 

 been described from different cases. Their interrelationship is not 

 entirely clear. In general, a division is made between those which 

 develop large spores and a more common small-spored variety. 



1 Gruby, Comptes rend, de 1'acad. des sci., 13, 1841. 



2 Sabouraud, Ann. de dermat. et de syph., 3, 1892, and 4, 1893. 



FIG. 152. ACHORION SCHOEN- 

 LEINII. Section of favus crust. 

 Stained by Gram. (After 

 Fraenkel and Pfeiffer.) 



