Preliminary Studies of Chromosome Rings in Brodiaea Lactea

Abstract

Associations of chromosomes during the heterotypic division resulting from segmental interchange are described: a ring or chain of 6 large chromosomes, a ring or chain of 4 large chromosomes, and a ring or chain of 4 small chromosomes. Associations of 6 large and 4 small chromosomes, or of 4 large and 4 small chromosomes, are found in a single pollen mother cell. Associations of 6 large and 4 large chromosomes in a cell were not observed. A possible explanation of these combinations is given, it being suggested that the ring of 4 large chromosomes is derived from the ring of 6. It is shown how a closed ring of 6 may break up into 2 closed rings of 4 and 2 chromosomes, respectively.