. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 450 THEO M. KONIJN AND KENNETH B. RAPER 'occurred earlier and in greater numbers in light than in darkness. Thus inter- and intraspecific differences in response to light must occur since cell populations of low density (200-250 ) were employed, as for D. discoideitin, KC-4(H). 2. The influence of lit/lit during the preaggregatvue stage on the rate of increase in the number of aggregations Myxamoebae of Dictyostelium discoideuui, NC-4(H), were grown in shaken cultures in the dark, harvested, washed and deposit
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 450 THEO M. KONIJN AND KENNETH B. RAPER 'occurred earlier and in greater numbers in light than in darkness. Thus inter- and intraspecific differences in response to light must occur since cell populations of low density (200-250 ) were employed, as for D. discoideitin, KC-4(H). 2. The influence of lit/lit during the preaggregatvue stage on the rate of increase in the number of aggregations Myxamoebae of Dictyostelium discoideuui, NC-4(H), were grown in shaken cultures in the dark, harvested, washed and deposited as drops on non- nutrient agar. Surveys at half-hour or hourly intervals after the cells started to aggregate indicated that the number of aggregations increased slowly if an initial. 8 10 12 14 16 18 Time in Hours 20 22 24 26 FIGURE 3. The effect of an increasing initial dark period on the rate of increase in number of aggregations. L: Light; D : Darkness; D-L: the drops were in darkness for the number of hours indicated before exposure to the light. dark period was lacking, or if this was insufficient to induce early aggregation (Fig. 3). After a dark period of 8 hours or longer, however, the number of aggregations increased rapidly, and within a period of one to three hours the final number was reached. Primary aggregations in populations exposed to light after a dark incubation of 10-13 hours were relatively large and the increase in number of sorocarps formed in such plates resulted, in substantial part, from a breaking up of the streams of pre-existing aggregations into smaller pseudoplasmodia. The sample curves presented in Figure 3 are taken from a much more extensive series twice confirmed in which periods of light and dark incubation were varied at incre- ments of less than four hours. 3. The Influence of light on chemotaxis Information relating to the phenomenon of chemotaxis was obtained by observ- ing the behavior of small populations of myxamoebae when
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
