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10164 results in Genetics

Page 508 of 509

  • MENDEL'S EXPERIMENTS WITH HIERACIUM

  • William Bateson, Gregor Mendel
  • Book:
    Mendel's Principles of Heredity
    Published online:
    07 September 2010
    Print publication:
    20 July 2009, pp 96-103
    First published in:
    1902

  • Summary

    Although I have already undertaken many experiments in fertilisation between species of Hieracium, I have only succeeded in obtaining the following 6 hybrids, and only from one to three specimens of them.

    H. Auricula ♀ × H. aurantiacum ♂

    H. Auricula ♀ × H. Pilosella ♂

    H. Auricula ♀ × H. pratense ♂

    H. echioides ♀ × H. aurantiacum ♂

    H. prœaltum ♀ × H. flagellare Rchb. ♂

    H. prœaltum ♀ × H. aurantiacum ♂

    The difficulty of obtaining a larger number of hybrids is due to the minuteness of the flowers and their peculiar structure. On account of this circumstance it was seldom possible to remove the anthers from the flowers chosen for fertilisation without either letting pollen get on to the stigma or injuring the pistil so that it withered away. As is well known, the anthers are united to form a tube, which closely embraces the pistil. As soon as the flower opens, the stigma, already covered with pollen, protrudes. In order to prevent self-fertilisation the anther-tube must be taken out before the flower opens, and for this purpose the bud must be slit up with a fine needle. If this operation is attempted at a time when the pollen is mature, which is the case two or three days before the flower opens, it is seldom possible to prevent self-fertilisation; for with every care it is not easily possible to prevent a few pollen grains getting scattered and communicated to the stigma.

  • A DEFENCE OF MENDEL'S PRINCIPLES OF HEREDITY

  • William Bateson, Gregor Mendel
  • Book:
    Mendel's Principles of Heredity
    Published online:
    07 September 2010
    Print publication:
    20 July 2009, pp 104-208
    First published in:
    1902

  • Summary

    “The most fertile men of science have made blunders, and their consciousness of such slips has been retribution enough; it is only their more sterile critics who delight to dwell too often and too long on such mistakes.”

    Biometrika, 1901

    INTRODUCTORY

    On the rediscovery and confirmation of Mendel's Law by de Vries, Correns, and Tschermak two years ago, it became clear to many naturalists, as it certainly is to me, that we had found a principle which is destined to play a part in the Study of Evolution comparable only with the achievement of Darwin—that after the weary halt of forty years we have at last begun to march.

    If we look back on the post-Darwinian period we recognize one notable effort to advance. This effort—fruitful as it proved, memorable as it must ever be—was that made by Galton when he enuntiated his Law of Ancestral Heredity, subsequently modified and restated by Karl Pearson. Formulated after long and laborious inquiry, this principle beyond question gives us an expression including and denoting many phenomena in which previously no regularity had been detected. But to practical naturalists it was evident from the first that there are great groups of facts which could not on any interpretation be brought within the scope of Galton's Law, and that by no emendation could that Law be extended to reach them.

Page 508 of 509