1. There is no evidence whatever of parallel threads or of pairing of thicker portions of the threads composing the synaptic knot as observed in
Oe. Lamarckiana by BOEDIJN.
2. Just before or in the second contraction the threads become differentiated into thicker and thinner portions. Time former grow in size and become univalent chromosomes.
3. A large closed circle of fourteen chromosomes is found at late prophase, which seems to be normally present in this species. Chromosomes composing the circle are joined end to end to one another.
4. The mode of gemini-formation in
Oe. sinuata is telosyndetic.
5. There is a tendency for adjacent chromosomes forming a circle to become attached in pairs. Diakinesis is not entirely absent in this species.
6. At metaphase, chromosomes are brought to the equatorial region, the appearance being zigzag as seen from the side. This zigzag arrangement may be due to the mode of separation of chromosomes, that is, alternate chromosomes in the circle pass to the same pole.
7. The behaviour of chromosomes in separation is generally normal, though irregularities may occur to some extent.
8. The second meiotic division is entirely regular.
9. Pollen tetrads are formed by the method of furrowing.
10. The flowing of substance (caryotin ?) from nucleolus into chromosomes, as CLELAND assumes, is not likely to occur in Oe. sinuata.
11. The haploid and diploid numbers of chromosomes in this species are seven and fourteen respectively.
抄録全体を表示