Perhaps no biological aspect of atomic energy has so caught the fancy of the public as the prospect of creating new plant varieties. There is something mysterious about pouring invisible energy into seeds or buds and watching for changes in the emerging leaves and flowers. There is also the challenge of the lottery in being unable to predict where, when, or in what form the alterations will appear. Although the claims of over-enthusiastic gardeners and seed dealers about astonishing new plants “created” by atomic radiation are doubted, clear proof exists even in the restrained scientific journals of hereditary changes caused by radiation. From more than 30 years of scientific study, certain conclusions have emerged. High-energy radiations can cause sudden hereditary changes (mutations) in any living thing: man, animal, microbe, or plant. Any feature of a plant subject to hereditary control—root, shoot, leaf, flower, or fruit—can be altered by radiation. Most of these changes are undesirable; they interfere with the normal state of biological affairs. A very small percentage of mutated organisms is improved in some way. So far changes cannot be controlled or predicted. To date fourteen new strains of crop plants improved by radiation have been put into production in various parts of the world. These varieties with their places and dates of release follow: 1. “Primex” white mustard, Sweden, 1950 2. “Chlorina Mutant” tobacco, Indonesia, about 1950 3. “Shafer’s Universal” bean, Germany, about 1950 4. “Regina II” summer oil rape, Sweden, 1953 5. “Weibull Stralart” fodder pea, Sweden, 1957 6. “Sanilac” navy bean, Michigan, 1957 7. “Pallas” barley, Sweden, 1958 8. “N. C. 4X” peanut, North Carolina, 1959 9. “Florad” oats, Florida, 1960 10. “Seaway” bean, Michigan, 1960 11. “Alamo-X” oats, Texas, 1961 12. “Gratiot” bean, Michigan, 1963 13. “Pennrad” barley, Pennsylvania, 1963 14. “Yukon-1” carnation, Connecticut, 1963 In these instances no desirable changes appeared in the plant grown directly from treated seeds, but they appeared several generations later. In most cases hundreds of thousands of plants were examined before the desirable ones were found. The desired changes were almost always accompanied by undesirable ones, and years of cross-breeding and “purifying” were necessary to obtain usable varieties. The technique of radiation breeding can be used on any form of life where large numbers can be grown and discarded at little cost. The output of penicillin has been increased a thousandfold by repeated mutations caused in the microorganism producing this antibiotic. Several studies on radiation breeding of poultry have been started.