390 RALPH S. LILLIE 



etc.); in such a case an increase of permeability to electrolytes 

 will involve decreased electrical polarization, and by the Lipp- 

 mann-Helmholtz law of electrocapillarity, also increased surface- 

 tension. With appropriate localization of the altered areas, 

 and a sufficient increase of surface-tension, a definite change 

 of form would result, as already indicated. 



This, however, is only one possible result of the assumed 

 change of surface-polarization. The complete effects of such 

 a change upon the physico-chemical conditions within the divid- 

 ing cell cannot be determined at present, and form a problem 

 for future research. This problem will be simplified — in some 

 of its terms at least — if it is recognized that dividing cells un- 

 dergo, at the time of change of form, surface-changes similar 

 to those which irritable elements like muscle-cells or nerve- 

 fibers undergo at the time of stimulation, and of which the bio- 

 electric variations are the most definite index. The time-rela- 

 tions of these changes are known to differ from cell to cell,^* 

 and the precise consequences within any particular cell vary 

 according to the specific constitution of the latter. But in all 

 cases the same general problem is met, namely: what are the 

 nature and conditions of the effects, chemical and other, result- 

 ing within the cell from alterations of surface-polarization? 

 Progress will have to be made in this fundamental problem 

 before the relation of the membrane-changes to cell-division 

 can be elucidated in detail. 



Cytoplasmic radiations appear to play a highly important 

 part in cell-division, although they vary greatly in their develop- 

 ment in different cells, and are usually absent in amitosis. Their 

 nature is still a subject of investigation; but the evidence^ ^ 

 appears to favor the view that they are essentially the expres- 

 sion of local differences of electrical potential within the cell, — 

 the polarized particles in the electrical field becoming oriented 



3^ For a table giving the time-relations of the bioelectric variations in a large 

 number of tissues and organisms, cf. Amer. Journ. Physiol., 1914, vol. 34, p. 417. 



'^ Especially the regular and symmetrical curvature which they show in the 

 spindle-area, and which seems inexplicable on any other hypothesis; mantle 

 and other astral fibers are also often curved in a manner resembling the lines of 

 force of intersecting electrical fields. 



