298 An Introduction to Medical Mycology 



and usually radial grooves appear near the periphery. In old cultures the 

 color may fade. Pleomorphism is rare. 



(e) Culture mount.— No free conidia or thyrsi are found. The mycelium 

 is short with numerous septums. Many irregular and bizarre branches are 

 present. In older cultures, chlamydospores are numerous. 



(f ) Filtered ultraviolet rays.— An infected hair differs in appearance 

 from a hair infected by one of the Microspora. The dull whitish fluorescence 

 is sometimes difficult to see well because the hairs are embedded in scales. 

 As in most compact growths, the colony is dull but clear. The color is un- 

 changed from that appearing in normal light. 



(g) Animal inoculation.— Successful transfers of this fungus have been 

 made to many animals, including guinea-pigs, dogs and cats. 



(h) Differential diagnosis.— On a direct mount of an infected hair, 

 the micro-organism is seen invading the hair shaft. It is to be further dif- 

 ferentiated from other endothrices such as A. schoenleini, T. crateriforme 

 and T. sulfureum. Trichophyton violaceum is the most likely endothrix if 

 the infected hair is short and twisted. The differential diagnosis is based 

 on the characteristics of the colony and on the appearance of the culture 

 mount. The favic chandeliers are seen only with A. schoenleini. Both T. 

 crateriforme and T. sulfureum show large numbers of microconidia. 



8. TRICHOPHYTON CRATERIFORME 



This fungus is found witli ringworm of the scalp and with tinea infections 

 of the smooth skin and nails. It is not uncommon in the countries of West- 

 ern Europe, but it is seldom encountered in this country. 



(a) Clinical characteristics.— The lesions of the scalp arc small and 

 may be few or numerous. These patches show subacute inflammatory 

 changes. On the glabrous skin, crusted, well defined lesions of mildly in- 

 flammatory type may develop. 



(b) Immunologic reactions.— The intracutaneous test dose of trichophy- 

 tin usually elicits a vigorous response. 



(c) Microscopic features.— Large spores in chains are found in the 

 hair shaft. At times the hair appears to be entirely filled with fungous 

 elements. 



(d) Cultural characteristics.— The colony grows slowly and at prime 

 covers only a portion of an agar slant. The surface of the growth is creamy- 

 white, compact and velvety. The central portion is depressed in an abrupt 

 craterifonn manner; tin's part <>l the colony is yellowish. Pleomorphisrh 

 is rare. 



(e) Culture mount.— Small conidia arc noted cither on short stocks or 



