Societies and Academies


    LONDON. Royal Society, June 1.—Sir Charles Sherrington, president, in the chair.—T. H. Morgan: The mechanism of heredity (Croonian lecture). The changes taking place when the germ-cells ripen are such that, granting the hereditary elements are carried by the chromosomes, the changes can serve as a mechanism, furnishing an explanation of the principles of heredity discovered by Mendel. In the course of the ripening of the germ-cells, irregularities occur at times in the distribution of the chromosomes, which can be followed in successive generations. The departures from the ordinary course of inheritance that are there shown, are found to be exactly related to the new distributions of the chromosomes. The facts furnish convincing testimony that the Mendelian characters are carried by the chromosomes. By the aid of the phenomenon known as “crossing-over” it is possible to determine that the hereditary elements lie in a single line in each chromosome. It is even possible to form a rough estimate of the upper limits of size of these elements, although at present such estimates are necessarily very crude, and are interesting only as the first attempt to determine the size of the “gene.”

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    Societies and Academies. Nature 109, 830–832 (1922).

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