Characteristics of Pathogenic Fungi 305 



under filtered ultraviolet rays. Fungi in nails, scales or macerated tissue do 

 not show any fluorescence. In culture, the granular type is typicalh bright 

 and clear and shows concentric hands of color, beginning with a light soft 

 blue-Violet in the center. The-edge is fawn-colored. With the compact and 

 fluffy types the color of the entire colony is bright indistinct mauve. The T. 

 nix cum type has a yellow tone throughout. 



(g) Animal i\o< i ivnov— The granular type of organism is inoculable 

 into guinea-pigs, dogs, cats and rabbits. The fluffy types have probably lost 

 their pathogenicity for these animals. 



(h) Differential diagnosis.— When T. gypseum invades a hair follicle, 

 it produces considerable inflammation. The hairs are not broken, but the) 

 may lack color. The fungi are not found in the shaft. The spores are in 

 linear formation and sparse, in contrast to those of species of Microsporum. 

 In examination of scales and macerated tissue it is difficult and at times im- 

 possible to determine species. On culture, T. purpureum must be differen- 

 tiated. The initiation of growth is faster in all types of T. gypseum. In the 

 ordinary type of T. gypseum the central fluffy portion is smaller than in T. 

 purpureum. In the fluffy type of T. gypseum the aerial hyphae are most 

 luxuriant, often being present on the sides of the tube. The fluffy form of 

 T. purpureum grows up in a hemispheric mass but is never seen along the 

 test tube. The color of the pigment is different in T. purpureum and in T. 

 gypseum. In the former it appears earlier and is deep rose-purple. In the 

 latter, the color is seen in older colonies and is dull rose-tan. The difference 

 between culture mounts of these two species is frequently difficult to deter- 

 mine. In T. purpureum we have never seen spirals and have noted few 

 fuseaux. 



BIBLIOGRAPHY 



Epstein, S.: Presentation of hypothesis that Trichophyton interdigitale is a degenerated Tri- 

 chophyton gypseum, J. Invest. Dermat. 1:141, 1938. This article summarizes the literature 

 and, with the report of the author's experiments, is a valuable discussion i>i tin's problem. 



Dowdtng, E. S., and Orr, H.: Three clinical types of ringworm due to Trichophyton gypseum, 

 Brit. J. Dermat. 49:298, 1937. 



11. TRICHOPHYTON PURPUREUM (BANG) 



Trichophyton purpureum ( Epidermophyton rubrum [Castellani], Tri- 

 chophyton rubidum | Priestly J, etc.) is frequently found in the tropics 

 and is also found in China and Japan; it is common in the southern part 

 of the United States. It often causes superficial fungous infections in New 

 York. 



(a) Clinical characteristics.— Few fungi are responsible for a more 

 typical clinical picture. The eruption may be localized or extensive. In 



