[223] The elongated or curved “macronucleus” of an Infusorian is to be looked upon as a single mass of chromatin, rather than as an aggregation of particles in a fluid drop, as in the case described. It has a shape of its own, in which ordinary surface-tension plays a very subordinate part.
[224] Théorie physico-chimique de la Vie, p. 73, 1910; Mechanism of Life, p. 56, 1911.
[225] Whence the name “mitosis” (Greek μίτος, a thread), applied first by Flemming to the whole phenomenon. Kollmann (Biol. Centralbl. II, p. 107, 1882) called it divisio per fila, or divisio laqueis implicata. Many of the earlier students, such as Van Beneden (Rech. sur la maturation de l’œuf, Arch. de Biol. IV, 1883), and Hermann (Zur Lehre v. d. Entstehung d. karyokinetischen Spindel, Arch. f. mikrosk. Anat. XXXVII, 1891) thought they recognised actual muscular threads, drawing the nuclear material asunder towards the respective foci or poles; and some such view was long maintained by other writers, Boveri, Heidenhain, Flemming, R. Hertwig, and many more. In fact, the existence of contractile threads, or the ascription to the spindle rather than to the poles or centrosomes of the active forces concerned in nuclear division, formed the main tenet of all those who declined to go beyond the “contractile properties of protoplasm” for an explanation of the phenomenon. (Cf. also J. W. Jenkinson, Q. J. M. S. XLVIII, p. 471, 1904.)
[226] Cf. Bütschli, O., Ueber die künstliche Nachahmung der karyokinetischen Figur, Verh. Med. Nat. Ver. Heidelberg, V, pp. 28–41 (1892), 1897.
[227] Arrhenius, in describing a typical colloid precipitate, does so in terms that are very closely applicable to the ordinary microscopic appearance of the protoplasm of the cell. The precipitate consists, he says, “en un réseau d’une substance solide contenant peu d’eau, dans les mailles duquel est inclus un fluide contenant un peu de colloide dans beaucoup d’eau ... Evidemment cette structure se forme à cause de la petite différence de poids spécifique des deux phases, et de la consistance gluante des particules séparées, qui s’attachent en forme de réseau.” Rev. Scientifique, Feb. 1911.
[228] F. Schwartz, in Cohn’s Beitr. z. Biologie der Pflanzen, V, p. 1, 1887.
[229] Fischer, Anat. Anzeiger, IX, p. 678, 1894, X, p. 769, 1895.
[230] See, in particular, W. B. Hardy, On the structure of Cell Protoplasm, Journ. of Physiol. XXIV, pp. 158–207, 1889; also Höber, Physikalische Chemie der Zelle und der Gewebe, 1902. Cf. (int. al.) Flemming, Zellsubstanz, Kern und Zelltheilung 1882, p. 51, etc.
[231] My description and diagrams (Figs 42–51) are based on those of Professor E. B. Wilson.
[232] If the word permeability be deemed too directly suggestive of the phenomena of magnetism we may replace it by the more general term of specific inductive capacity. This would cover the particular case, which is by no means an improbable one, of our phenomena being due to a “surface charge” borne by the nucleus itself and also by the chromosomes: this surface charge being in turn the result of a difference in inductive capacity between the body or particle and its surrounding medium. (Cf. footnote, p. 187.)