318 At 1 Introduction to Medical Mycology 



usually occur in groups, are typical. Small septate filaments may also be 

 noted. Budding is never seen as reproduction takes place by division. 



(d) Cultural characteristics.— After four weeks the colony on dex- 

 trose agar has the shape of a low cone and a diameter of about 45 mm. 

 The margin is even. The surface is covered with a grayish nap. Zonation 

 may appear. Thus, successively from the center to the periphery, a typical 

 colony presents concentric zones of olive-black, brownish olive, olive- 

 black, brownish olive, olive-black, olive-gray and gray. The colors vary 

 somewhat according to the underlying mycelium and the degree of sporula- 

 tion. After two or three months the colonies are brown. 



(e) Culture mount.— A branched or unbranched conidiophore bears 

 brownish-olive spores at the tip and, in later cultures, on the sides as well. 

 A secondary and occasionally a tertiary spore may form from the first 

 spore. Spores sometimes appear in branching conidial chains. The spores 

 may vary considerably in size and shape. Disjunctors, defined by Emmons 

 and Carrion as "the narrowed end of the spore and the thickened wall 

 which surrounds and terminates it," are usually to be found. In a specimen 

 from old cultures or in one grown on corn meal agar, the phialophora type 

 of conidiophore may appear. It is bottle-shaped, being restricted where 

 the spore is formed. Above this the wall flares, forming a cup from which 

 conidia are extruded. 



(f ) Filtered ultraviolet radiation.— There is no change in color, the 

 black being more intense. No fluorescence is to be noted. 



(g) Animal inoculation.— Characteristic lesions are produced in rats. 

 Emmons and Carrion found that several saprophytic species of Hormo- 

 dendrum were also pathogenic for rats, with only mild lesions. Azulay 

 could inoculate his strain into the testes of guinea-pigs and white rats. 



(h) Differential diagnosis.— Acrotheca and Trichosporum may be 

 readily excluded by the observation of branching chains of spores. 



BIBLIOGRAPHY 



Azulay, R. D.: Experimental studies on chromoblastomycosis, J. Invest. Dermat. 6:281, 1945. 



Conant, N. F., and Martin, D. S. : Morphologic and serologic relationships of various fungi 

 causing dermatitis verrucosa (chromoblastomycosis), Am. J. Trop. Med. 17:553, 1937. 



Emmons, C. W., and Carrion, A. L.: Hormodendrum pedrosoi: Etiological agent in chromo- 

 blastomycosis, Puerto Rico J. Pub. Health & Trop. Med. 11:639, 1936. 



Moore, M.: Organisms of chromoblastomycosis of North America and South America, Science 

 83:603, L936. 



18. HORMODENDRUM COMPACTUM 



Carrion isolated this micro-organism in 1936 from lesions suggesting 

 psoriasis and lupus erythematosus which were limited to an arm. In places 



