[432] This rule, undreamed of by Errera, supports and justifies the cardinal assumption (of which we have had so much to say in discussing the forms of cells and tissues) that the incipient cell-wall behaves as, and indeed actually is, a liquid film (cf. p. 306).

[433] Cf. p. 254.

[434] Cf. Harting, op. cit., pp. 22, 50: “J’avais cru d’abord que ces couches concentriques étaient produites par l’alternance de la chaleur ou de la lumière, pendant le jour et la nuit. Mais l’expérience, expressément instituée pour examiner cette question, y a répondu négativement.”

[435] Liesegang, R. E., Ueber die Schichtungen bei Diffusionen, Leipzig, 1907, and other earlier papers.

[436] Cf. Taylor’s Chemistry of Colloids, pp. 146–148, 1915.

[437] Cf. S. C. Bradford, The Liesegang Phenomenon and Concretionary Structure in Rocks, Nature, XCVII, p. 80, 1916; cf. Sci. Progress, X, p. 369, 1916.

[438] Cf. Faraday, On Ice of Irregular Fusibility, Phil. Trans., 1858, p. 228; Researches in Chemistry, etc., 1859, p. 374; Tyndall, Forms of Water, p. 178, 1872; Tomlinson, C., On some effects of small Quantities of Foreign Matter on Cry­stal­li­sa­tion, Phil. Mag. (5) XXXI, p. 393, 1891, and other papers.

[439] A Study in Cry­stal­li­sa­tion, J. of Soc. of Chem. Industry, XXV, p. 143, 1906.

[440] Ueber Zonenbildung in kolloidalen Medien, Jena, 1913.

[441] Verh. d. d. Zool. Gesellsch. p. 179, 1912.