144 CLINICAL BACTERIOLOGY AND H^MATOLOGY 



the disease it causes is readily cured. It also causes ring-- 

 worm 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 ringworm 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 unhesi- 

 tatingly 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 care- 

 fully examined for ringworm fungi. 



Favus is caused by a closely allied organism, the Achorion 

 Schdnleinii; 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 inva- 

 sion of the hair. The scutulttm is composed of vertical 

 mycelial filaments, which branch, and which appear to be 

 composed of short rods. There are often oval spores at the 

 free ends of these- branches, and, according to Sabouraud, 

 branching* into three occurs (trichotomous branching), and 

 is very characteristic, though difficult to see. The radiation 

 of several filaments from one point, and the fact that these 

 appear to be made up of short lengths, gives rise to an 

 appearance which has been compared to that of the meta- 

 tarsal bones, and the term " favic tarsus " has been applied. 



When favus affects the hair (Plate VI., Fig. 5), the cuticle 



