抄録
In the PMCs of Trillium kamtschaticum, the frequencies of the combinations of two chromosomes which participate in an exchange were investigated with several materials irradiated at various stages of the meiotic prophase.
In the materials irradiated in late October, the observed frequencies in the various combinations were roughly in accord with their expected values calculated on the basis of the proportionality to chromosome length and the random distribution of chromosomes in a prophase nucleus. On the contrary, in the cases irradiated later than the end of October, certain greater deviation from the expectation was demonstrated.
Comparing the relative frequencies of the exchanges between homologous chromosomes, it was clearly shown that the values decrease in the cases of irradiation at November, December, and January of the next year.
These results may be taken to indicate that chromosome pairing takes place later than October in the PMCs of this plant.
