[233] On the effect of electrical influences in altering the surface-tensions of the colloid particles, see Bredig, Anorganische Fermente, pp. 15, 16, 1901.
[234] The Cell, etc. p. 66.
[235] Lillie, R. S., Amer. J. of Physiol. VIII, p. 282, 1903.
[236] We have not taken account in the above paragraphs of the obvious fact that the supposed symmetrical field of force is distorted by the presence in it of the more or less permeable bodies; nor is it necessary for us to do so, for to that distorted field the above argument continues to apply, word for word.
[237] M. Foster, Lectures on the History of Physiology, 1901, p. 62.
[238] Op. cit. pp. 110 and 91.
[239] Lamb, A. B., A new Explanation of the Mechanism of Mitosis, Journ. Exp. Zool. V, pp. 27–33, 1908.
[240] Amer. J. of Physiol. VIII, pp. 273–283, 1903 (vide supra, p. 181); cf. ibid. XV, pp. 46–84, 1905. Cf. also Biological Bulletin, IV, p. 175. 1903.
[241] In like manner Hardy has shewn that colloid particles migrate with the negative stream if the reaction of the surrounding fluid be alkaline, and vice versa. The whole subject is much wider than these brief allusions suggest, and is essentially part of Quincke’s theory of Electrical Diffusion or Endosmosis: according to which the particles and the fluid in which they float (or the fluid and the capillary walls through which it flows) each carry a charge, there being a discontinuity of potential at the surface of contact, and hence a field of force leading to powerful tangential or shearing stresses, communicating to the particles a velocity which varies with the density per unit area of the surface charge. See W. B. Hardy’s paper on Coagulation by Electricity, Journ. of Physiol. XXIV, p. 288–304, 1899, also Hardy and H. W. Harvey, Surface Electric Charges of Living Cells, Proc. R. S. LXXXIV (B), pp. 217–226, 1911, and papers quoted therein. Cf. also E. N. Harvey’s observations on the convection of unicellular organisms in an electric field (Studies on the Permeability of Cells, Journ. of Exper. Zool. X, pp. 508–556, 1911).
[242] On Differences in Electrical Potential in Developing Eggs, Amer. Journ. of Physiol. XII, pp. 241–275, 1905. This paper contains an excellent summary of various physical theories of the segmentation of the cell.