162 ON THE INTERNAL FORM AND [ch. 



is an admirable mechanism for the making of waves ; with a lump 

 of ice in it, it becomes an efficient and self-contained mechanism 

 for the making of currents. The great cosmic mechanisms are 

 stupendous in their simplicity ; and, in point of fact, every great 

 or little aggregate of heterogeneous matter (not identical in 

 'phase") involves, ipso facto, the essentials of a mechanisna. 

 Even a non-living colloid, from its intrinsic heterogeneity, is in 

 this sense a mechanism, and one in which energy is manifested 

 in the movement and ceaseless rearrangement of the constituent 

 particles. For this reason Graham (if I remember rightly) speaks 

 somewhere or other of the colloid state as "the dynamic state of 

 matter"; or in the same philosopher's phrase (of which Mr 

 Hardy* has lately reminded us), it possesses "ewer^rmf." 



Let us turn then to consider, briefly and diagrammatically, the 

 structure of the cell, a fertilised germ-cell or ovum for instance, 

 not in any vain attempt to correlate this structure with the 

 structure or properties of the resulting and yet distant organism ; 

 but merely to see how far, by the study of its form and its changing 

 internal configuration, we may throw light on certain forces which 

 are for the time being at work within it. 



We may say at once that we can scarcely hope to learn more 

 of these forces, in the first instance, than a few facts regarding 

 their direction and magnitude ; the nature and specific identity 

 of the force or forces is a very different matter. This latter 

 problem is likely to be very difficult of elucidation, for the reason, 

 among others, that very different forces are often very 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 " caryokinetic " figures of which we are about to 

 speak. One student may, like Rhumbler, choose to account for 

 them by an hypothesis of mechanical traction, acting on a reticular 

 web of protoplasm J ; another, like Leduc, may shew us how in 



* Hardy, W. B., On some Problems of Living Matter (Guthrie Lecture), 

 Tr. Physical Soc. London, xxviii, p. 99-118, 1916. 



I As a matter of fact both phrases occur, side by side, in Graham's classical 

 paper on "Liquid Diffusion apphed to Analysis," Phil. Trans, cli, p. 184, 1861; 

 Chem. and Phys. Researches (ed. Angus Smith), 1876, p. 554. 



X L. Rhumbler, Mechanische Erklarung der Aehnhchkeit zwischen Magne- 



