Abstract
SUMMARY Emmonsiella capsulata, the perfect state of Histoplasma capsulatum, is differentiated from other genera of Gymnoascaceae by the formation of tight coils radially arising from the ascogonium and by sinuately branched, anastomosed peridial hyphae that arise laterally from these coils. Emmonsiella capsulata is heterothallic with two mating types. Isolates from soil and those of human origin mate successfully, indicating their genetic compatibility.