. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 452 THEO M. KONIJN AND KENNETH B. RAPER of washed, non-nutrient agar of low rigidity (Konijn and Raper, 1961). The soft agar gel provided a means of measuring interpopulational responses since it was rigid enough to keep all the cells within the confines of the drop in the absence of an extraneous stimulus (Fig. 4), but was, at the same time, sufficiently soft to allow the myxamoebae to move outside the drop boundary if attracted by a chemo- tactic stimulus secreted by a neighboring population. Fortunately for our pur- poses
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 452 THEO M. KONIJN AND KENNETH B. RAPER of washed, non-nutrient agar of low rigidity (Konijn and Raper, 1961). The soft agar gel provided a means of measuring interpopulational responses since it was rigid enough to keep all the cells within the confines of the drop in the absence of an extraneous stimulus (Fig. 4), but was, at the same time, sufficiently soft to allow the myxamoebae to move outside the drop boundary if attracted by a chemo- tactic stimulus secreted by a neighboring population. Fortunately for our pur- poses, the myxamoebae that were attracted beyond the edge of such a drop moved into the agar (Fig. 5) and did not return to their "home" drop until its residual cells formed their own aggregates. Thus data relating to the effect of chemotactic stimuli could be obtained by employing droplets of cells of one preaggregative "age" to act as attractors and cells that were less mature in point of time to serve as responders. Drops containing attracting and responding myxamoebae were. 500 700 900 1100 Distance of Attraction in Microns 1300 FIGURE 6. The percentages of myxamoeba populations that showed a response to develop- ing aggregations under different light conditions, and the distances between the nearest margins of these populations and the aggregations that attracted them. Graphic representation of data contained in Table I. O : Constant light. w : Constant light, but with plates sealed after the responding drops were deposited on the agar. • : Constant darkness. deposited on the agar surface at different distances from each other and the plates were then incubated in either light or darkness. The distance over which attraction could take place was taken as a measure of the strength of the stimulus produced by the population of aggregating myxamoebae. This distance wras measured not between the proximal edges of the two drops but from the center of the develop
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
