Siliceous Shells of Protozoa


WE regret that circumstances have prevented an earlier reply to Prof. T. D. A. Cockerell's letter published in NATURE of June 28. In our opinion, there can be no question of either convergent or divergent evolution in the case of organisms belonging to separate families as widely separated as Miliolina and Miliammina. We thought we had made their absence of relationship sufficiently clear by the statement that Miliammina was a siliceous isomorph of Miliolina, isomorphism being understood among rhizopodists, at any rate, to mean the development of similar structures in unrelated organisms owing to unknown physical or biological conditions.

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HERON-ALLEN, E., EARLAND, A. Siliceous Shells of Protozoa. Nature 126, 436 (1930).

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