. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 464 W. R. JONES, III AND D. FRANCIS time is one phenomenon which is influenced by light. Konijn and Raper (1965) found that aggregation occurs soonest in constant light in P. pallidum, which in this respect differs from /). discoidcuin- and A. rosca where a dawn following a night of certain length is optimal (Konijn and Raper, 1965; Reinhardt, 1968). In all of these cases, light lias its effect on post-vegetative, preaggregative cells. 5Gr- 40 30 20 10 O. 400 500 600 WAVELENGTH 700 800 FIGURE 2. The action spectrum of light
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 464 W. R. JONES, III AND D. FRANCIS time is one phenomenon which is influenced by light. Konijn and Raper (1965) found that aggregation occurs soonest in constant light in P. pallidum, which in this respect differs from /). discoidcuin- and A. rosca where a dawn following a night of certain length is optimal (Konijn and Raper, 1965; Reinhardt, 1968). In all of these cases, light lias its effect on post-vegetative, preaggregative cells. 5Gr- 40 30 20 10 O. 400 500 600 WAVELENGTH 700 800 FIGURE 2. The action spectrum of light induced aggregation. Centers/drop above back- ground (ordinate) are plotted against wavelength in m^t (abscissa). "Background" is the number of centers which appear in drops kept in constant darkness. Each point is the average of counts made on 6 drops. O, • indicate results of two separate experiments using X 103 ergs/cnr/sec at each wavelength. Cultures were harvested at X 10° cells/ml, and plated at 5 X 105 cells/ml; background equals 45 and 50 centers/drop. A indicates results of a third experiment using X 10" ergs/cm°/sec at each wavelength. Cultures were har- vested at X 10" cells/ml, and plated at X 10° cells/ml; background equals 48 centers/drop. and must induce in them some cellular process which leads to aggregation. Some observations by Shaffer (1961) give a hint as to what this process might be. He found that aggregations in P. violacenm are started by special founder cells which apparently secrete large amounts of acrasin, for they directly attract neighboring cells. Furthermore, Shaffer noted that the number of founders increased sud-. 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 Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
