RINGWORM.. 117 



This fungus is a rare cause of ringworm of the scalp, 

 and the disease it causes is readily cured. It also 

 causes ringworm of the body and of the beard region, 

 which the endothrix does not attack. According to 

 Sabouraud (to whose work on these organisms we owe 

 most of our knowledge on the subject) kerion is always 

 caused by this organism, but this is not generally 

 accepted. It appears, however, to be a fact that sup- 

 purative lesions (folliculitis, kerion, &c.) are usually 

 caused by this fungus. 



This species is often derived from one of the lower 

 animals, especially from the horse, cat, and dog. 



Favus is caused by a closely allied organism, the 

 achorion ScJwnkinii. This may be demonstrated by 

 either of the processes already described. It consists 

 of mycelial threads which are not continuous, but are 

 composed of short rods, The whole has an appearance 

 which has been compared to that of the metatarsal 

 bones, and this resemblance is increased by the fact 

 that sometimes several filaments radiate from one point, 

 forming the " favic tarsus." 



The identification of the variety of organism which is 

 present does not usually present great difficulties. The 

 first point to be looked to is the arrangement of the 

 spores. If these are present in an irregular mosaic the 

 microsporon is present ; if they form filaments some- 

 what resembling those of a streptococcus the organism 

 is a trichophyton. To settle which it is look to see 

 whether the cuticle is present, and whether the fungus 

 invades the interior of the hair. This can usually be 

 determined by focussing up and down until you see an 

 " optical section " of the hair in question. It is impor- 

 tant not to be deluded by the fact that the fungus which 

 lies on the outside of the hair will appear to be inside it 

 if a surface view only is taken. 



