172 



INFECTIONS CAUSED BY MOLDS 



large spores (5 to 7 microns in diameter) . Species of the first group 

 grow more rapidly in artificial culture than those of the second. 



The small-spored species may be confused with Microsporum if 

 the differentiation is made solely on a hasty examination of the hairs, 

 for they present the same general appearance — a few* articulated 

 hyphae within the hair and numerous spores on the surface forming 

 a sheath. However, these spores, unlike those of Microsporum, are 



Fig. 85. A suppurating ringworm of the beard ("sycosis"). This is due to an 



Ectothrix Trichophyton. 



produced by a fragmentation of hyphae and therefore tend to be 

 arranged in chains rather than in an irregular mosaic. The spores 

 of the two fungi are about of a size. In microsporosis one rarely 

 sees as much inflammatory reaction with a tendency to deep infiltra- 

 tion of the skin as is characteristic of the small-spored ectothrix 

 species of Trichophyton. 



, In adults the small-spored ectothrix species cause infections of the 

 beard region, the smooth skin, especially the extensor surfaces of 

 the forearms, and the feet. In children lesions of the scalp, face 

 and hands occur. The lesions, when on the smooth skin, are usually 

 of the circular type characteristic of ringworms. 



The small-spored group form white, cream-colored, yellow, or pink 

 colonies which vary from granular, stellate colonies to snow-white, 

 floccose, "powder-puff" colonies. Many species have been described 

 ^nd differentiated on the b^^is of colony type. The most common 



