536 PATHOGENIC FUNGI 



Microspora. — The small-spored ringworm parasites are re- 

 sponsible for a large proportion of the ringworms of the scalp 

 occurring in children, and only occasionally cause affections of 

 the other parts of the body. In the initial lesion in the epi- 

 dermis a fine mycelium, 1-5 ^i in diameter, may be observed, 

 composed of rectangular elements, demonstrable in stained 

 preparations. This mycelium penetrates into the hairs where 

 they emerge from their sheaths, and grows up and down in 

 them. When an infected hair is examined, it is. found to be 

 encased with a mass of spores which have the characters of an 



Fin. 163. i — Hair infected with Microsporon aiidoirini. Photograph of 

 unstained preparation, x 500. 



irregular mosaic, the elements being frequently crushed together 

 in polygonal forms and showing no tendency to an arrangement 

 in rows. These spores are about 2 /j. in diameter, but in potash 

 preparations may appear laiger, — up to 5 /jl. According to 

 Sabouraud, the appearance on the hair results from intra- 

 capillary mycelial threads breaking out at numerous points on 

 the surface and there undergoing irregular longitudinal and 

 transverse splitting, to form the spores. The mycelium can be 

 demonstrated by mounting the hair in 7 per cent, potash 

 solution and disengaging the adherent and obscuring spores by 

 gently rubbing the hair between the slide and the cover-glass. ■ 

 The species most commonly present is the Microsporon audouini. 



1 For Figs. 163-169, 174, we are indebted to the kindness of Dr. It. Cranston 

 Low. 



