The Somatic Chromosomes of Trillium
1937 年 FujiiJubilaei 巻 2 号 p. 857-866
詳細
1937 年 FujiiJubilaei 巻 2 号 p. 857-866
1. In spite of their smaller size the somatic chromosomes are well worthy of investigation.
2. Improvements in cytological technique are here describec which make possible as accurate fixation of the somatic cells as that afforded by the best procedure in the Gase of the smear method.
3. The somatic cells an account of the difficultie:s of fixatior have not been made to bear the extreme load of theory which has been imposed an the reproductive elements.
4. The essential organization of the dividing nucleus is chromatidal or chromonemal.
5. In the metaphase the chromatids, originating in the anaphase or late metaphase of the preceding divisions, become separated from nne another and divest themselves of their spiral involvements.
6. At this stage they subdivide longitudinally.
7. Later as the metaphase passes into the anaphase the two chromatids of each daughter ehromosomes become spirally involved in opposite directions.
8. This involvement reaches its extreme condition in the fully developed anaphase.
9. The chromatidal pairs undergo strong contraction in the telophase.
10. This condition is followed later by a loosening in which the pairs of chromatids again reveal their identity. At this stage their spiral structure is no Tonger obvious.
11. Their identity is apparently lost in the resting stage.
12. Nucleoli make their appearance in the resting nuclei.
13. The revival of nuclear activity brings with it the disappearance of the nucleoli and the reestablishment of the filamentous organization.
14. The nuclear filament is clearly double and consists of two chromatids reversely coiled.
15. The spiralization gradually disappears with the development of the metaphase.
16. The so-called chromomeres are apparently optical illusions based an the misinterpretation of gyres or contragyres resulting from imperfect preservation.
17. The study of somatic divisions with improved methods is apparently destined to throw a new fundamental light an the nature of the meiotic or reduction division.
