• O. H. Frankel

      Articles written in Journal of Genetics

    • Inversions inFritillaria

      O. H. Frankel

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      1. In twenty-two species ofFritillaria no evidence of inversions has been found.

      2. In the following species, viz.F. dasyphylla 2x, F. dasyphylla 3x, F. pudica 3x, F. citrina andF. recurva 3x, the results of crossing-over in inversions have been observed.

      3. InversionA inF. dasyphylla 2x, located at, or near, the distal end of anS bivalent, has a frequency of about 70 per cent of one or two chiasmata in the inversion.

      4. The expected configurations for more than one chiasma proximal to the inversion are analysed.

      5. Chiasma formation in the bivalent carrying inversionA has been studied. The frequencies of the various configurations indicate a slight preponderance of comparate chiasmata.

      6. Cell-wall formation by acentric fragments and univalents has been studied inF. dasyphylla. The formation of a separate cell wall requires a position of the lagging unit satisfying the maximum repulsion from both daughter nuclei. The possession of a centromere by the micronucleus is not apparently indispensable.

    • Studies inHebe - II. the significance of male sterility in the genetic system

      O. H. Frankel

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      1. Male sterility with female fertility has been observed in nature in eight forms of the genusHebe, comprising five species and one species hybrid.

      2. Degeneration occurs rapidly and with regularity, either in pachytene or in the course of pollen development, at a stage which is characteristic for each form.

      3. InH. Townsoni male sterility is associated with a timing disturbance which causes a chimerical arrangement of division stages within loculi, and also with a frequent failure of pairing of one bivalent. A causal relationship cannot be ascertained. The three phenomena may indicate a major physiological disturbance.

      4. Male sterility has mainly been ascertained under experimental conditions, especially after induced self-fertilization. Under conditions of relative isolation, which favours its occurrence, male sterility serves as a mechanism for reducing self-fertilization.

      5. In gynodioecious species, the production of “female” plants may often, originally, be determined by single genes for pollen sterility.

    • The causal sequence of meiosis - I. Chiasma formation and the order of pairing inFritillaria

      O. H. Frankel

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