[472] Celestine, or celestite, is SrSO4 with some BaO replacing SrO.
[473] With the colloid chemists, we may adopt (as Rhumbler has done) the terms spumoid or emulsoid to denote an agglomeration of fluid-filled vesicles, restricting the name froth to such vesicles when filled with air or some other gas.
[474] Cf. Koltzoff, Zur Frage der Zellgestalt, Anat. Anzeiger, XLI, p. 190, 1912.
[475] Mém. de l’Acad. des Sci., St. Pétersbourg, XII, Nr. 10, 1902.
[476] The manner in which the minute spicules of Raphidiophrys arrange themselves round the bases of the pseudopodial rays is a similar phenomenon.
[477] Rhumbler, Physikalische Analyse von Lebenserscheinungen der Zelle, Arch. f. Entw. Mech. VII, p. 103, 1898.
[478] The whole phenomenon is described by biologists as a “surprising exhibition of constructive and selective activity,” and is ascribed, in varying phraseology, to intelligence, skill, purpose, psychical activity, or “microscopic mentality”: that is to say, to Galen’s τεχνικὴ φύσις, or “artistic creativeness” (cf. Brock’s Galen, 1916, p. xxix). Cf. Carpenter, Mental Physiology, 1874, p. 41; Norman, Architectural achievements of Little Masons, etc., Ann. Mag. Nat. Hist. (5), I, p. 284, 1878; Heron-Allen, Contributions ... to the Study of the Foraminifera, Phil. Trans. (B), CCVI, pp. 227–279, 1915; Theory and Phenomena of Purpose and Intelligence exhibited by the Protozoa, as illustrated by selection and behaviour in the Foraminifera, Journ. R. Microscop. Soc. pp. 547–557, 1915; ibid., pp. 137–140, 1916. Prof. J. A. Thomson (New Statesman, Oct. 23, 1915) describes a certain little foraminifer, whose protoplasmic body is overlaid by a crust of sponge-spicules, as “a psycho-physical individuality whose experiments in self-expression include a masterly treatment of sponge-spicules, and illustrate that organic skill which came before the dawn of Art.” Sir Ray Lankester finds it “not difficult to conceive of the existence of a mechanism in the protoplasm of the Protozoa which selects and rejects building-material, and determines the shapes of the structures built, comparable to that mechanism which is assumed to exist in the nervous system of insects and other animals which ‘automatically’ go through wonderfully elaborate series of complicated actions.” And he agrees with “Darwin and others [who] have attributed the building up of these inherited mechanisms to the age-long action of Natural Selection, and the survival of those individuals possessing qualities or ‘tricks’ of life-saving value,” J. R. Microsc. Soc. April, 1916, p. 136.
[479] Rhumbler, Das Protoplasma als physikalisches System, Jena, p. 591, 1914; also in Arch. f. Entwickelungsmech. VII, pp. 279–335, 1898.
[480] Verworn, Psycho-physiologische Protisten-Studien, Jena, 1889 (219 pp.).
[481] Leidy, J., Fresh-water Rhizopods of N. America, 1879, p. 262, pl. xli, figs. 11, 12.