[213] Gallardo, A., Essai d’interpretation des figures caryocinétiques, Anales del Museo de Buenos-Aires (2), II, 1896; La division de la cellule, phenomène bipolaire de caractère electro-colloidal, Arch. f. Entw. Mech. XXVIII, 1909, etc.
[214] Arch. f. Entw. Mech. III, IV, 1896–97.
[215] On various theories of the mechanism of mitosis, see (e.g.) Wilson, The Cell in Development, etc., pp. 100–114; Meves, Zelltheilung, in Merkel u. Bonnet’s Ergebnisse der Anatomie, etc., VII, VIII, 1897–8; Ida H. Hyde, Amer. Journ. of Physiol. XII, pp. 241–275, 1905; and especially Prenant, A., Theories et interprétations physiques de la mitose, J. de l’Anat. et Physiol. XLVI, pp. 511–578, 1910.
[216] Hartog, M., Une force nouvelle: le mitokinétisme, C.R. 11 Juli, 1910; Mitokinetism in the Mitotic Spindle and in the Polyasters, Arch. f. Entw. Mech. XXVII, pp. 141–145, 1909; cf. ibid. XL, pp. 33–64, 1914. Cf. also Hartog’s papers in Proc. R. S. (B), LXXVI, 1905; Science Progress (n. s.), I, 1907; Riv. di Scienza, II, 1908; C. R. Assoc. fr. pour l’Avancem. des Sc. 1914, etc.
[217] The configurations, as obtained by the usual experimental methods, were of course known long before Faraday’s day, and constituted the “convergent and divergent magnetic curves” of eighteenth century mathematicians. As Leslie said, in 1821, they were “regarded with wonder by a certain class of dreaming philosophers, who did not hesitate to consider them as the actual traces of an invisible fluid, perpetually circulating between the poles of the magnet.” Faraday’s great advance was to interpret them as indications of stress in a medium,—of tension or attraction along the lines, and of repulsion transverse to the lines, of the diagram.
[218] Cf. also the curious phenomenon in a dividing egg described as “spinning” by Mrs G. F. Andrews, J. of Morph. XII, pp. 367–389, 1897.
[219] Whitman, J. of Morph. II, p. 40, 1889.
[220] “Souvent il n’y a qu’une séparation physique entre le cytoplasme et le suc nucléaire, comme entre deux liquides immiscibles, etc.;” Alexeieff, Sur la mitose dite “primitive,” Arch. f. Protistenk. XXIX, p. 357, 1913.
[221] The appearance of “vacuolation” is a result of endosmosis or the diffusion of a less dense fluid into the denser plasma of the cell. Caeteris paribus, it is less apparent in marine organisms than in those of freshwater, and in many or most marine Ciliates and even Rhizopods a contractile vacuole has not been observed (Bütschli, in Bronn’s Protozoa, p. 1414); it is also absent, and probably for the same reason, in parasitic Protozoa, such as the Gregarines and the Entamoebae. Rossbach shewed that the contractile vacuole of ordinary freshwater Ciliates was very greatly diminished in a 5 per cent. solution of NaCl, and all but disappeared in a 1 per cent. solution of sugar (Arb. z. z. Inst. Würzburg, 1872, cf. Massart, Arch. de Biol. LX, p. 515, 1889). Actinophrys sol, when gradually acclimatised to sea-water, loses its vacuoles, and vice versa (Gruber, Biol. Centralbl. IX, p. 22, 1889); and the same is true of Amoeba (Zuelzer, Arch. f. Entw. Mech. 1910, p. 632). The gradual enlargement of the contractile vacuole is precisely analogous to the change of size of a bubble until the gases on either side of the film are equally diffused, as described long ago by Draper (Phil. Mag. (n. s.), XI, p. 559, 1837). Rhumbler has shewn that contractile or pulsating vacuoles may be well imitated in chloroform-drops, suspended in water in which various substances are dissolved (Arch. f. Entw. Mech. VII, 1898, p. 103). The pressure within the contractile vacuole, always greater than without, diminishes with its size, being inversely proportional to its radius; and when it lies near the surface of the cell, as in a Heliozoon, it bursts as soon as it reaches a thinness which its viscosity or molecular cohesion no longer permits it to maintain.
[222] Cf. p. 660.