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| b. Chemistry, Biology, Geology |
| 1915 |
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| Alfred Wegener (1880–1930) gave the classic expression of the controversial theory of continental drift in Die Entstehung der Kontinente und Ozeane. | 1 |
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| 1921 |
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| Hans Spemann (1869–1941) postulated an organizer principle that was responsible for the formative interaction between neighboring embryonic regions. He stimulated contemporary embryologists to search for the inductive chemical molecule. | 2 |
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| 1927 |
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| Hermann J. Muller (1890–1967) announced that he had successfully induced mutations in fruit flies with x-rays. This provided a useful experimental tool, yet in retrospect gave warning to the generations of the 1940s and 1950s of a danger in the release of atomic energy. | 3 |
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| 1929 |
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| Alexander Fleming (1881–1955) announced that the common mold Penicillium had an inhibitory effect on certain pathogenic bacteria. It was not until 1943 under the pressures of World War II, however, that the first antibiotic, penicillin, was successfully developed. | 4 |
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| 1930 |
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| Ronald A. Fisher (1890–1962) established in The Genetical Theory of Natural Selection that superior genes have a significant selective advantage, thus testifying that Darwinian evolution was compatible with genetics. | 5 |
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| 1941 |
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| George W. Beadle (1903–89) and Edward L. Tatum (1909–75) described an experimental assay that evaluated the exact relationships between specific mutant genes in mold and particular stages in the metabolic process. | 6 |
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| 1944 |
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| Ostwald T. Avery (1877–1955) and collaborators announced they had transmuted one type of pneumococcus bacteria into a second type by the transfer of DNA molecules. (See Science and Technology) | 7 |
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