iv] AND STRUCTURE OF THE CELL 293 



direction and magnitude; tli£ nature and specific identity of the 

 force or forces is a very different matter. This latter problem is 

 likely to be difficult of elucidation, for the reason, among others, 

 that very different forces are often much alike in their outward and 

 visible manifestations. So it has come to pass that we have a 

 multitude of discordant hypotheses as to the nature of the forces 

 acting within the cell, and producing in cell division the "caryo- 

 kinetic" figures of which we are about to speak. One student may, 

 like Rhumbler, choose to account for them by an hj^othesis of 

 mechanical traction, acting on a reticular web of protoplasm*; 

 another, hke Leduc, may shew us how in many of their most striking 

 features they may be admirably simulated by salts diffusing in a 

 colloid medium; others, hke Lamb and Graham Cannon, have 

 compared them to the stream-hnes produced and the field of force 

 set up by bodies vibrating in a fluid; others, like Gallardof and 

 Rhumbler in his earher papers J, insisted on their resemblance to 

 certain phenomena of electricity and magnetism §; while Hartog 

 believed that the force in question is only analogous to these, and 

 has a specific identity of its own||. All these conflicting views are 

 of secondary importance, so long as we seek only to account for 

 certain configurations which reveal the direction, rather than the 

 nature, of a force. One and the same system of lines of force may 

 appear in a field of magnetic or of electrical energy, of the osmotic 

 energy of diffusion, of the gravitational energy of a flowing stream. 

 In short, we may expect to learn something of the pure or abstract 

 dynamics long before we can deal with the special physics of the 



* L. Rhumbler, Mechanische Erklarung der Aehnlichkeit zwischen magne- 

 tischen Kraftliniensystemen und Zelltheilungsfiguren, Arch. f. Entw. Mech. xv, 

 p. 482, 1903. 



t A. Gallardo, Essai d'interpretation des figures caryocinetiques, Armies del 

 Museo de Buenos- Aires (2), ii, 1896; Arch. f. Entw. Mech. xxvm, 1909, etc. 



X Arch.f. Entw. Mech. ill, iv, 1896-97. 



§ On various theories of the mechanism of mitosis, see (e.g.) Wilson, The Cell 

 in Development, etc.; Meves, Zelltheilung, in Merkel u. Bonnet's Ergehnisse der 

 Anatomic, etc., vii, viii, 1897-98; Ida H. Hyde, Amer. Journ. Physiol, xii, pp. 241- 

 275, 1905; and especially A. Prenant, Theories et interpretations physiques de 

 la mitose, Journ. de VAnat. et Physiol, xlvi, pp. 511-578, 1910. See also A. Conard, 

 Sur le mecanisme de la division cellulaire, et sur les bases, morphologiques de la 

 Cytologie, Bruxelles, 1939: a work which I find hard to follow. 



II M. Hartog, Une force nouvelle: le mitokinetisme, C.R. 11 Juli 1910; Arch. f. 

 Entw. Mech. xxvii, pp. 141-145, 1909; cf. ibid, xl, pp. 33-64, 1914. 



