THE ULTRASTRUCTURE OF CONIDIOGENESIS IN STILBELLA-ANNULATA

Conidiogenesis in the synnematous hyphomycete Stilbella annulata (Berk . and M.A. Curtis) Seifert is initially enteroblastic with basipetally retrogressive secession and enteroblastic conidiogenous cell prolifer ation, where each conidiogenous cell apparently produces a maximum of seven conidia. The first conidium is produced enteroblastically. Chain s of synnemata are formed as a result of two processes: (a) from conid ia which may not normally be seceded and then germinate into hyphae, o r be normally seceded and germinate above the conidiogenous locus with no physical attachment to the underlying structure, except the mucila ge in which the conidia germinate; (b) the continuation of normal vege tative growth after the full complement of conidia has been produced. Ultrastructurally, the marginal hyphae contained no septa, which expla ined the non-abscission of these structures. Morphologically they are therefore modified hyphae and not analogous to conidiogenous cells.