| Abstract: | SYNOPSIS. Conjugation in Paramecium aurelia has been studied in live and sectioned cells and oral development studied following ultraviolet microbeam irradiation. The live cells allow a clear correlation to be made between nuclear behavior and gullet development. The paroral cone lies at the level of the buccal overture. The new oral area develops while the old one is still present, the latter structure being still visible after the conjugants have separated. Sectioned material confirms the fact of cytoplasmic fusion at the level of the paroral cones. It also confirms the appearance of new buccal organelles on the right side of the buccal overture of the pre-existing gullet. Ultraviolet microbeam irradiation of the buccal area shows that the posterior edge of the buccal overture must remain undisturbed for normal development. Irradiation of the anterior edge of the buccal overture also affects development. These results differ from earlier work on fissioning cells. Discussion of these differences leads to the conclusion that the factors controlling stomatogenesis are developmentally regulatory. |
