. Cell heredity. Cytogenetics. 210 CELL HEREDITY. 4 6 8 10 12 Generations After Irradiation 14 FIGURE The relation of bacterial mutation induced by ultraviolet light to the rate of division at various temperatures; the same curve describes the results at 37, 25, and 16°C (from Witkin, 1953, Proc. Nafl. Acad. Sci. Wash., 39:427). This concept agrees with other work indicating that mutation is fastest when cell di\isions are taking place, and that the temperature coefficients of the two processes are the same (Figure ). Yet Stubbe, in Germany, long ago showed that mutations could occur e
. Cell heredity. Cytogenetics. 210 CELL HEREDITY. 4 6 8 10 12 Generations After Irradiation 14 FIGURE The relation of bacterial mutation induced by ultraviolet light to the rate of division at various temperatures; the same curve describes the results at 37, 25, and 16°C (from Witkin, 1953, Proc. Nafl. Acad. Sci. Wash., 39:427). This concept agrees with other work indicating that mutation is fastest when cell di\isions are taking place, and that the temperature coefficients of the two processes are the same (Figure ). Yet Stubbe, in Germany, long ago showed that mutations could occur even in stored seeds. The rate was, however, not constant but increased with time, suggesting that as aging progresses the mutation rate changes in accordance with changes in metabolism. Perhaps the genes slowly replicated in the stored seeds at an increasing rate. It has also been shown that non- dividing bacteria can mutate at a slow rate which does remain constant with time. The mutation rate is a function of the ease with which vari- ous sugars can be utilized, and metabolism may be slowed down to such an extent by low temperature or starvation that new mutations cannot be observed to take place. By the use of chloramphenicol, which in-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sager, Ruth; Ryan, Francis J. (Francis Joseph), 1916-. New York, Wiley
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