54 An Introduction to Medical Mycology 



the largest; secondary lesions are usually smaller. The duration is usually 

 short ( under three months ) . There is noticeable loss of hair in the affected 

 patches with slight or, more commonly, marked inflammation and tender- 

 ness. Broken-off hairs may be found at the periphery of a lesion. 



(3) Microsporum fulvum— An infection due to this fungus may or may 

 not be acquired from an animal. The duration is usually short (one month 

 or less). There is a tendency for the infection to remain localized to only 

 one part of the scalp. Inflammation is usually marked, and kerion is not 

 unusual. In our experience there is always noticeable edema of the affected 

 tissues. 



(4) Trichophyton violaceum.— In this type of ringworm of the scalp, 

 small scattered patches develop insidiously. The duration of the infection is 

 frequently many months or even years. The disease may not be cured at 

 puberty. The fungus invades the cortex of the hair (endothrix infection), 

 and the hairs break off close to the scalp. The appearance of the infected 

 scalp has led to the name "black dot" ringworm. In many instances, the 

 hairs break off just below the surface of the scalp, which results in a 

 minute secondary pyogenic infection with subsequent crusting, not unlike 

 that due to ingrowing hairs of the beard. We have never found T. violaceum 

 in the pus in these lesions, although we have tried innumerable times. After 

 many months there is usually some atrophy or scarring. 



(5) Trichophyton craterifonne — The clinical appearance and course of 

 tinea due to this organism differ materially from those of infection due to 

 T. violaceum, since the infection may appear in one or more patches and 

 the infected hairs usually do not break off at the surface of the scalp; rarely 

 the clinical appearance is that of "black dot" ringworm. In addition there is 

 usually secondary infection; crusting and kerion are seen in three of five 

 cases. As in kerion due to other fungi, the infected hairs are shed because 

 of the inflammatory process, and cure may be spontaneous. The organism 

 invades the cortex of the hair ( endothrix infection ) and is not transmissible 

 to laboratory animals. Infection with T. craterifonne may be of several 

 weeks' duration when first observed. 



(6) Trichophyton sulfureum.— -The only scalp which we observed to be 

 infected with this fungus presented a diffuse reddened scaly rash over 

 the occiput. Throughout this area were numerous small stumps, inter- 

 spersed with normal hair. 



(7) Achorion (Trichophyton) schoenleini.— This micro-organism (essen- 

 tially an endothrix Trichophyton ) is the cause of an infection designated as 

 favus. The clinical manifestations are usually characteristic. The usual focus 

 is the scalp, from which the disorder may spread to the nails or to the 

 glabrous skin. At first there is a small spot of scaly inflammation. Around 



