152 



MEDICAL MYCOLOGY 



or ovoid, 7-9/a in diameter. They are discharged from the ascus {Fig. 25, 

 6, 7) by the rupture of the wall where little or no cellulose was deposited, 

 either directly into the nasal cavity (Graham 1932) or into the lymphatics. 

 Mature asci are 200-300/a in diameter, sometimes larger at the surface of the 

 polyp. Spores are spread in the connective tissue by the tracts of lymph 

 exudate, the spherules disappear and the vegetative stage begins by absorp- 

 tion of the fluid in the interstices of the connective tissue, and apparently the 

 cycle is repeated. 



Attempts to cultivate it have been unsuccessful, the only case of partial 

 success being that of Rettie, reported by Ashworth, where the spores seemed 

 to elongate to cells 19 x 4.5^i and divide by fission. Contaminating bacteria 

 prevented further work with these cultures, and the author was not even sure 

 that the elongated cells had come from the spores of Rhinosporidium. 



Fig. 25. — Rhinosporidium Seeheri; 1, early trophic stag-e, 12xl3/t; 2, after first nuclear 

 division, about 40/t ; S, section of stage with about 500 nuclei, showing beginning of spore and 

 annulus ; k, section of a spore 10x7/t, showing wall, nucleus with karyosome, vacuoles, and 

 refringent spherules ; 5, similar spore with eccentric nucleus ; 6, 7, ruptured asci. (After 

 Ashworth 1923.) 



fflSTOPLASMA 



Histoplasma Darling, Jour. Amer. Med. Assn. 46: 1283-1285, 1906.; Arch. 

 Int. Med. 11: 107-123, 1908; Jour. Exp. Med. 11: 515-531, 1909. 



The type species is Histoplasma capsulatum Darling. 



Vegetative mycelium in culture producing chlamydospores and conidia. 

 In tissues existing as yeast cells with thick capsules, invading the mononu- 

 clear cells of the blood and the endothelial cells in the smaller lymph and 

 blood vessels and capillaries. In cultures, the hyphae are septate and mul- 

 tinucleate, producing tuberculate asci with many ascospores per ascus. 

 Chlamydospores and conidia are produced on certain media. 



This genus seems close to Paracoccidioides in general appearance, but the 

 nuclei which wiU form the ascospores do not migrate into the tubercles on 



