Abstract
1. Almost all of small seeds set on the tetraplold radish in the free pollination of 2x- and x-pollen grains were found cytologically to be triploid hybrids.
2. The triploid hybrid showed a variation of chromosome configuration at meiosis from 9III to 3III+6II+6I, with 6III+3II+3I as the mode. The frequency of appearance of univalents is 25.7% at metaphase I of PMC-s. About half of lagging univalents at anaphase I divided longitudinally and their halves went to opposite daughter nuclei. The elimination of univalents at telophase II was found to be about 15.4% of the theoretical total number of univalents.
3. It is especially noted that triploid plants have unexpectedly high percentage of good pollen grains and of set seeds, that is 72.3% of normal pollen grains and 1.87 seeds per capsule as compared with 98.0% of normal pollen grains and 3.50 seeds per capsule in the diploid variety.
