536 



PATHOGENIC FUNGI 



The pathological lesions produced by the microspora and 

 trichophyta are similar, though those of the latter are the more 

 severe. In each case there is primarily a premature detach- 

 ment of epithelial squames with subjacent inflammation in the 

 corium, frequently followed by a slight hyperkeratosis, especially 

 marked around and within the hair sheaths. Follicular pustules 

 are also common and in the '{ most severe trichophytal cases a 



FIG. 165. Hair infected with large-spored ringworm. Photograph 

 of unstained preparation, x 500. 



Note. The sizes of the spores in Figs. 163 and 165 are not comparable, as 

 in photographs of such thick preparations it is impossible to sharply focus 

 the outlines. 



granulomatous condition (kerion) of the true skin, with rela- 

 tively massive follicular suppuration, occurs. 



Achoria. These organisms are responsible for the various 

 clinical manifestations grouped under the name of favus which 

 affect both the hairy and smooth parts of the body. The 

 characteristic of these is the development of round sulphur- 

 yellow discs (scutula) each with a depression in the middle which 

 in hairy parts often corresponds to the position of a hair follicle. 

 These discs really consist of dense masses of fungoid growth 

 (Fig. 168). The feature is an initial vigorous invasion of the 



