On the Behavior of Chromosomes in the Meiotic Phase of Some Artificially Raised Papaver Hybrids. (With Plate III and one Text-figure)

抄録

1. In the prophase of the meiotic division of tile Papaver hybrid, chromosomes forming gemini, unite end to end, not side by side.
2. There appear 11 bivalent chromosomes and 10 univalent chromosomes in the first meiotic division. The bivalent chromosomes form the equatorial plate first; all the eleven chromosomes may pass to the anaphase simultaneously, or seven of them first and remaining four afterward; the univalent chromosomes may follow the same process after the halves of the bivalent chromosomes left the equator for the opposite poles of spindle. They make the longitudinal split at the equator and the halves move to the opposite poles.
3. The univalent chromosomes, which remained outside the spindle or did not get to the pole before the nuclear membrane appears, are left in the cytoplasm.
4. In the second divison of meiosis, the large chromosomes, probably derived from the bivalent chromosomes from the equatorial plate earlier than those from univalent chromosomes. As in first division, some chromosomes derived from the univalent chromosomes are left in the cytoplasm. Some of them remains as isolated chromosomes in the cytoplasm, but some, single or two or more in groups are inclosed by themselves in separate membranes and thus form miniature nuclei.
5. As the result of the irregular behavior of the chromosomes, occasionarily two daughter nuclei of the first division of meiosis, connected by a bridge of isolated chromosomes, unite to form a single nucleus. The union of two nuclei, beloning to two different spindles of the second meiotic division, also takes place. The result in the appearance much resemble an amitotic division. Such nuclei form a kind of diploid pollen grains.
6. The irregular behavior of chromosomes in the meiotic division, the union of two nuclei, and dropping of certain chromosome cause the abnormalities of pollen grains, not only in shape and size, but also in the combinations of the heredity substances. This may contribute to the origin of the variation or new forms in the offsprings on the one hand, while this may affect the viability of the male gamates and cause the sterility on the other hand.
7. F₁ plants between Papaver somniferum and P. orientale are more vigorous than their parent plants. The F₁ plant appears mostly like P. orientale the _??_ parent, but in some external characters it is intermediate between both parents. The male gamates are mostly sterile.