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Small grains in the USDA World Collection total about 44,500 accessions. This constitutes a valuable, growing, and much used gene bank. It contains only a few duplicates, but many individual genes are represented over and over. Therefore, the probability of adding altogether new genes to the bank is diminishing, and only as truly exotic, untapped gene pools are discovered in the world is the trend altered. It is feared that agricultural improvement and increased utilization and grazing of natural areas is erasing forever some rich, but unknown, gene centers. Future generations may, therefore, have to do without needed genes that we have now and do not know how to preserve. They would have to wait until nature evolved them, or they would have to find and use ways to induce the genes by directed evolutionary processes.

Interference effects caused by the passage through solids or liquids of a continuous-wave laser beam at 6328 A are reported. These effects may cause serious distortion of the beam even at low laser power. The observations tend to support the view that these effects are due to heating. Measurements of the defocusing of the beam may be used to provide estimates of the small absorption coefficients of the materials.