In an ordinary agar-plate culture of the collective amoeba, or cellular slime mould, Polysphondylium violaceum, the solitary phase ends when compact and increasingly refractive cell clumps develop among the unoriented cells and secrete the chemotactic factor acrasin. Neighbouring cells may crawl towards them, either singly or aggregated in streams, which relay chemotactic and contact guidance centrifugally (Shaffer, 1957a, 1958). As already briefly reported (Shaffer, 1959), aggregation centres may be started by single, differentiated cells ; these have been called founders.

Copyright © 1961 The Company of Biologists Ltd.
1961
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