HE distributive pairing model of meiosis for the female of Drosophila melanoTgastcr (R. F. GRELL 1962a) postulates a chronological series of events which includes exchange pairing, exchange, distributive pairing, and segregation, in the order given. The model was dictated by genetic data, derived from studies of nonhomologous pairing, which showed that the frequency with which nonhomo!oguos pai...