Genetic and Cytological Interference

Abstract

PAIRED meiotic chromosomes may have their four chromatids or strands involved in a variety of ways in two adjacent chiasmata. In most studies of chiasmata the materials have not been favourable enough to permit the tracing of all four strands through two or more chiasmata. We have recently been able to do this in forty-eight complete pollen mother cells of Trillium erectum, and have observed therein eight types of chiasma pairs. These are shown diagrammatically in Fig. 1 together with their frequencies and interstitial lengths (alternative one-plane representations of these three-dimensional configurations are here neglected).