Problems of Modern Biology in Relation to Atomic Physics. A Series of Lectures by M. Delbrück Physics Dept., Vanderbilt University given at the Vanderbilt University School of Medicine April and May 1944. Second Printing (without change) February, 1946. COPY OF NORMAN H. HOROWITZ

1 leaf, 45 pp. Mimeographed. Original wrappers, stapled. Tear in title page, else Very Good. COPY OF NORMAN H HOROWITZ (see photo). Second Printing (without change) February, 1946. The first printing was in 1944. Although the two printings are each mimeographed and have the same text, they do differ. The first printing is printed on one side of the paper only, and the lectures are separately paginated, whereas in the second printing they are printed on both sides of the paper and are continuously paginated. The first printing is spiral bound with a blue paper wrapper that is heavier than the paper of the text, whereas in the second printing it is stapled and the wrappers are of the same paper as the text leaves. In the second printing of 1946, there is a statement on the first leaf of the text: "Through the courtesy of Dr. Max Delbrück, Vanderbilt University, and at the suggestion of its Panel on Physics, the Committee on Growth of the National Research Council has reproduced these lectures on 'Problems of Modern Biology in relation to Atomic Physics' and takes pleasure in distributing them as a service to its panels and to the grantees of the American Cancer Society." OCLC locates copies of this second printing in 7 US libraries. I. Limitations of Atomic Physics as Applied to Biology; II. Oxido-Reductions; III. Energy-Coupling; IV. Photosynthesis I; V. Photosynthesis II; VI. Genetics I; VII. Genetics II; VIII. Radiation Effects; IX. Bacterial Viruses; X. General Summary. Delbrück "complained frequently that his teaching duties left too little time for research. He needed time to prepare a series of lectures he was to give at Vanderbilt's School of Medicine in April and May 1944 entitled 'Problems of Modern Biology in Relation to Atomic Physics.' These presentations were reproduced without change in February 1946 and distributed to the grantees of the American Cancer Society; they remained unpublished otherwise. After describing his view of the limitations of applying atomic physics to biology, Max proceeded in these lectures to try to determine how far atomic physics could help in understanding living cells. He discussed metabolism; photosynthesis; genes, their actions and mutations; and bacterial viruses. After first dealing with what he called ordinary biochemistry ('what the cell does with substrates introduced from without'), Max introduced genetics by reviewing the steps that lead to the picture of the gene as a material particle. He described the importance of Mendel's experiments, which showed there are factors that segregate and that can be recovered unchanged from a variety of phenotypes. He explained that cytologists were able to localize these factors in sequence along chromosomes. Then he speculated about the outlook of bacterial genetics: 'We owe our present knowledge, as it were, to two lucky accidents, the bisexuality of the higher organisms and the occurrence of crossing over at meiosis. Since our knowledge of the gene is so intimately tied to those two features, we may wonder whether genes exist also in organisms where there is no sex and no crossing over, as in bacteria.' Max pointed out that genetics now required a biochemical approach: geneticists had produced 'three magnificent problems' for biochemists: 1. What do genes consist of? 2. How do they reproduce? 3. How do they act? Max thus publicly stated his appreciation of biochemistry about a month before he learned of Avery's transforming principle" (Fischer, Ernst Peter & Carol Lipson: Thinking about Science. Max Delbrück and the Origins of Molecular Biology, p. 155). These lectures should not be confused with Delbrück's well-known lecture published in 1949, "A Physicist Looks at Biology." The Nobel Prize in Physiology or Medicine in 1969 was awarded jointly to Max Delbrück, Alfred D. Hershey and Salvador E. Luria "for their discoveries concerning the replication mechanism and the genetic structure of viruses.".…