The code of life / [Ernest Borek].

  • Ernest Borek
Date:
1965
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The code of life / [Ernest Borek]. Source: Wellcome Collection.

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    teacher and remained in this category because he kept failing the examinations for a full-fledged position. It has been sug gested that Mendel was stimulated to start his experiments by a dispute with his examiner in botany on the last of his unsuccessful examinations. Whatever were his motivations, he pursued his studies on plant hybridization in the tiny garden of the monastery of St. Thomas at Brunn, Austria, with such devotion and brilliance that he was lifted from his self-imposed anonymity and is counted among those men of rare genius who are the first to discover a law of Nature. He studied the effects of the crossbreeding of two plants endowed with contrasting traits. He started by planting different peas, tall and short, in the monastery garden. If these two varieties of peas were allowed to self-fertilize, with no possibility of cross- fertilization, the plants yielded seeds which bred true to type: they grew into plants, tall or short, like their parents. But if a tall and a short pea were crossed-fertilized or hybridized, the seeds from such a union gave rise only to tall peas. Mendel did not stop there. He patiently crossed these tall peas of mixed ancestry and collected their seeds. Out of these seeds grew both tall and short peas. He carefully recorded his seeds and crops and found from over a thousand different plantings that the tall and short grandchildren always appeared in a definite ratio: 75 percent tall and 25 percent short. He repeated these studies with red- and white-flowered peas. When he cross-fertilized these flowers he found that all the seeds gave rise to red flowers. But this new generation of red flowers, when cross-fertilized, pro duced seeds from which grew both red and white peas. He found 6022 red and 2001 white flowers, again a ratio of three to one (75.1 to 24.9 percent, to be more exact). Mendel concluded that there are factors in peas which deter mine their color and height. The factor for whiteness or shortness remains dormant in the first generation after the crossbreeding
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