The Factorization of Cyclic Reduced Powers by Secondary Cohomology Operations.

I Lewin, J. C., Science, 112, 652 (1950). 2 In the experiments reported here, cultures were grown on minimal medium plus sodium acetate (0.2 gm per 100 ml). The minimal medium, described in Levine, R. P., and Ebersold, W. T., Zeit. Vererbungs., 89, 632 (1958), was altered by a fivefold increase in the concentration of Beijerinck's solution. 3 Arnon, D. I., Plant Physiol., 24, 1 (1949). 4The author is indebted to Miss Jana Moravkova and Dr. Ian Gibbons for several electron micrographs of Chlamydomonas chloroplasts. 5 Smillie, R. M., and Fuller, R. C., Plant Physiol., 34, 651 (1960). 6 Arnon, D. I., Nature, 184, 10 (1959). 7Levine, R. P., Nature (in press). 8 Lindberg, O., and Ernster, L., in Methods of Biochemical Analysis, ed. D. Glick (New York: Interscience Publ., 1956), vol. 3, p. 1. 9 Note added in proof: Subsequent experiments have shown that extracts of ac-21 prepared by sonication are capable of carbon dioxide fixation in the light in the presence of adenosine triphosphate.