The Morphology, Cytology, and Sexuality of the Homothallic Rhizopus sexualis (Smith) Callen

Abstract

Rhizopus sexualis (Smith) is fully described morphologically with the following interesting points: production of zygospores ladderwise on one pair of zygophores; regeneration of single suspensors gives only homothallic mycelium; both normal and auxiliary sporangia were produced ; plasma excretion occurs; and 2 terminal zygophores may produce a zygospore. It hybridized with R. nigricans ( + ) and ( [long dash]), Mucor hiemalis ( [long dash]), and Absidia cylindro-spora ( [long dash]) and there was an imperfect sexual reaction with other spp. It probably arose as a result of a mutation. Believes homothallic zygophores do not have changing sex but the 2 hyphae must be of different age.