307 This cellular pattern would seem to be related to the ãcohesion figuresã described by Tomlinson in various surface-films (Phil. Mag. 1861 to 1870); to the ãtesselated structureã in liquids described by Professor James Thomson in 1882 (Collected Papers, p. 136); and to the tourbillons cellulaires of Prof. H. Bûˋnard (Ann. de Chimie (7), XXIII, pp. 62ã144, 1901, (8), XXIV, pp. 563ã566, 1911), Rev. gûˋnûˋr. des Sci. XI, p. 1268, 1900; cf. also E. H. Weber. (Poggend. Ann. XCIV, p. 452, 1855, etc.). The phenomenon is of great interest and various appearances have been referred to it, in biology, geology, metallurgy and even astronomy: for the flocculent clouds in the solar photosphere shew an analogous configuration. (See letters by Kerr Grant, Larmor, Wager and others, in Nature, April 16 to June 11, 1914.) In many instances, marked by strict symmetry or regularity, it is very possible that the interference of waves or ripples may play its part in the phenomenon. But in the majority of cases, it is fairly certain that localised centres of action, or of diminished tension, are present, such as might be provided by dust-particles in the case of Darlingãs experiment (cf. infra, p. 590).
308 Ueber physikalischen Eigenschaften dû¥nner, fester Lamellen, S.B. Berlin. Akad. 1888, pp. 789, 790.
309 Certain palaeontologists (e.g. Haeusler and Spandel) have maintained that in each family or genus the plain smooth-shelled forms are the primitive and ancient ones, and that the ribbed and otherwise ornamented shells make their appearance at later dates in the course of a definite evolution (cf. Rhumbler, Foraminiferen der Plankton-Expedition, 1911, i, p. 21). If this were true it would be of fundamental importance: but this book of mine would not deserve to be written.
310 A Study of Splashes, p. 116.
311 See Sillimanãs Journal, II, p. 179, 1820; and cf. Plateau, op. cit. II, pp. 134, 461.
312 The presence or absence of the contractile vacuole or vacuoles is one of the chief distinctions, in systematic zoology, between the Heliozoa and the Radiolaria. As we have seen on p. 165 (footnote), it is probably no more than a physical consequence of the different conditions of existence in fresh water and in salt.
313 Cf. Doflein, Lehrbuch der Protozoenkunde, 1911, p. 422.