9. Segregation of pollen size in translocation heterozygotes.

Plants heterozygous for T1‑5-6‑7 (giving a ring of 8 chromosomes) were used; 200 pollen grains measured per plant, 5 plants of each stock. Three of 10 F₁ plants showed bimodal curves for pollen size (larger diameter) and one tended toward bimodality. No bimodality was noted in the normal or the homozygous translocation parents; or in normal material in other experiments. If growth factors tend to be expressed in the gametophyte generation, bimodality might be expected for pollen in certain of the crosses with translocation stocks giving larger rings.