Il6 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



endothrix attack birds, and may occasionally be communicated 

 to man. 



The T. ectothrix, or, as some call it, ecto-endothrix, forms (like 

 the microsporon) a sheath round the outside of the hair, to 

 which it is closely applied, like the bark to a tree, but, unlike the 

 small-spored variety, does not destroy the cuticle. The spores 

 are about as large as in the preceding species, and are arranged 

 in chains ; this fact, together with the position of the fungus 

 with regard to the hair, will enable a diagnosis to be made 

 (Plate VI., Fig. I). 



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. 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 suppurative lesions (folliculitis, kerion, etc.) are usually 

 caused by this fungus. 



This species is often derived from one of the lower animals, 

 especially from the horse, cat, and dog. 



In addition to these fungi which attack the hair there is 

 a group of fungi, called by Sabouraud the epidermophytons, 

 which attack the surface epidermis, but not the hairs. Several 

 varieties are known, but their discrimination is a matter for the 

 expert, and is unimportant. They cause the well-known ring- 

 worm of the groin, or eczema marginatum, and, as has been 

 recently shown by Whitfield and Sabouraud (independently), 

 various forms of what would formerly have been described as 

 eczema (and very often recognized unhesitatingly as " gouty ") on 

 the hands or feet, or both. This may be acute, and vesicular or 

 bullous, or may occur in an intertriginous form resembling the 

 eczema marginatum of the groin, or a more chronic form with* 

 hyperkeratosis. In the light of these discoveries we see that all 

 cases of eczema limited to the palms or soles, or to both, should 

 be most carefully examined for ringworm fungi. 



Favus is caused by a closely allied organism, the A chorion 

 Schonleinii ; other forms are known, but are less important. This 

 may be demonstrated by either of the processes already described. 

 It affects the skin in two ways: by the formation of the 

 characteristic scutula and by the ringworm-like invasion of the 

 hair. The scutulum is composed of vertical mycelial filaments, 



