310 



MEDICAL MYCOLOGY 



is filamentous and produces peculiar spherical conidia or chlamy- 

 dospores, covered with finger-like outgrowths, 10 to 25 /x in 

 diameter. 



Its relationship to other fungi is not clearly established. It has 

 been interpreted to be related to Coccidioides and placed in the 

 Genus Posadasia anions the Endomvcetaceae. Studies by Howell 

 ( 1939), however, in which Histoplasma was compared with Sepe- 



Fig. 67. Histoplasma capsulatimi. A. Mycelium from culture. B. Aleuro- 

 spores that form on aerial mycelium, showing characteristic protrusions. 

 C. Aleurospore in optical section. D. Aleurospores that form submerged. 



Their walls are smooth. 



donium and other fungi related to Sepedonium show that these 

 two genera are closely related Fungi Imperfecti. Sepedonium is 

 never yeast-like, however, and it may produce phialospores, which 

 are not known to be developed among species of Histoplasma. 

 Conant (1941) reported that in its parasitic form within tissues 

 Histoplasma is always yeast-like with thick capsules. On blood 

 agar incubated at 37° C it buds, yeast-like, but at room tempera- 

 ture it is myceloid and forms tuberculate chlamydospores. 

 Conant too regards it as closely related to Sepedonium. 



PHIALOPHORA VERRUCOSA 



This is amono; the organisms involved in a chronic infection of 

 the skin and subcutaneous tissues, characterized by the presence 



