THE HIGHER BACTERIA 159 



ACHORION SCHONLEINI 



Achorion schonleini is present in the hairs and scabs of tinea favosa or favus. 



Morphology. When one of the crusts containing a hair is removed from 

 the affected area and examined microscopically, branched chains of mycelial 

 spores are observed within the hair. These spores are round, or nearly so, and 

 measure from 3 to 6 ^u in diameter. Here and there along the hair mycelial 

 filaments occur and in the crusts or epithelium adjacent to them masses of 

 tangled filaments occur. The filaments are delicate and vary in length; some 

 show several branches and others do not branch. 



Growth. Achorion schonleini is aerobic and grows at temperatures between 

 i5C. and 38C., best at 33C. 



Neutral Glycerin Bouillon. A dark yellow surface pellicle form on this 

 medium. 



Neutral Glycerin Agar. A dark yellow, dry, wrinkled, umbilicated film 

 develops. 



Potato. Growth first is grayish yellow; then darker, until the potato turns 

 brown. It covers the surface with a thick film. 



Pathogenesis. Achorion schonleini is the cause of favus. 



"Tinea favosa, or favus, is a contagious vegetable parasitic disease of the 

 skin, characterized by pin-head to pea-sized, friable, umbilicated, cup-shaped, 

 yellow crusts, each usually perforated by a hair. It is usually met with upon 

 the scalp, but may occur upon any part of the integument" (Stelwagon). 



Achorion schonleini, or a closely related organism, causes favus of dogs and 

 mice. 



Diagnosis. Bacteriological diagnosis is based on microscopic examination 

 of crusts and hairs removed from affected surfaces. 



The crusts and hairs are placed in a drop of 20 to 40 per cent, potassium 

 hydrate solution on a slide and a cover glass is dropped upon it. Gently warm 

 the preparation for a few seconds and then examine. When it is desirable to 

 keep preparations for a time, after warming the slide is placed on a cold surface 

 to rapidly cool it and when cool a drop of eosin-tinted glycerin is allowed to run 

 between cover and slide. 



TRICHOPHYTON AND MICROSPORON AUDONINI 



Tinia trichophytina, or ring worm, is a vegetable parasitic disease which 

 affects various portions of the epithelial surface of the body, chiefly the scalp 

 or bearded region of the trunk. Several triophy ta and the microsporon audouini 

 act as exciting causes of the disease. 



The same condition has been observed in dogs and other animals. 



Diagnosis. Bacteriological diagnosis is based upon microscopic examina- 

 tion of hairs removed from the center and outer zone of diseased areas. 



The hairs are placed in a drop of 20 to 40 per cent, potassium hydrate solu- 

 tion and a cover glass dropped on them. Several slides should be gently warmed 

 and allowed to stand at room temperature for several minutes before examina- 

 tion. Other slides should be heated until steam arises and then placed on a 



