The Origin and Behavior of Chiasmata. I. Diploid and Tetraploid tulipa

Abstract

Smear preparations of the pollen mother cells of diploid Tulipa australis, its variety "Tulipa persica," and the tetraploid T. stellata were used. Terminalization of chiasmata in Tulipa is incomplete between diplotene and metaphase. This genus, compared with Fritillaria, Rosa and others, indicates that 3 conditions determine the degree of terminalization: the length of the 2 chromosomes, the number and position of the chiasmata, and the rate of movement of chiasmata. These studies make it seem probable that terminalization occurs in all organisms.