NUCLEAR DIVISION WITHOUT CELL- DIVISION. I/ I 



spindle-fibers of dividing cells. The resemblance of the lines of 

 the mitotic figure to the electrical and magnetic lines of force 

 has, needless to say, long been the subject of frequent comment. 

 Now we know that if such an electrical potential -difference 

 between exterior and interior exists, a condition of electrical 

 strain or tension must also exist, the direction of whose lines of 

 traction must correspond with that of the electrical lines of force. 

 It has also been shown that the direction of the fibrils of coagu- 

 lum in fixed preparations of albumin-solutions subjected during 

 fixation to mechanical strain coincides closely with the direction 

 of this strain (cf. Hardy, 1 Fischer -). We may therefore infer from 

 the direction of the fibrils in fixed preparations of dividing cells 

 that a condition of strain or tension exists between interior and 

 periphery of the cell during mitosis, similar to that which would 

 exist in the presence of an electrical potential-difference of the kind 

 imagined above. This agreement confirms the theory that such 

 potential-difference does actually exist. The tendency of the 

 alveoli in echinoderm eggs to dispose themselves along corre- 

 sponding lines is similarly to be interpreted as an instance of the 

 tendency possessed by polarizable particles in an electric field to 

 arrange themselves in rows along the lines of force. 3 



It may fairly be claimed therefore that it is no mere assumption 

 to suppose that during cleavage the surface of the egg is charged 

 differently from the interior. If such a surface-charge is present 

 it will infallibly produce a lowering of the surface-tension with 

 corresponding changes in the form of the egg. Cleavage, on 

 the present theory, is the result of such changes : its conditions 

 will be considered below in further detail. 



If we grant then that during mitosis the surface of the egg is 

 charged differently from the interior the question arises : how is 

 this difference of potential established and maintained? In other 

 words, what influence directs ions of one sign toward the periph- 

 ery, the others toward the interior of the egg ? This question ap- 



1 Hardy, Journal of Physiology, 24, 1899, p. 158. 



2 Fischer, Fixierung, Farbung und Bau des Protoplasmas, Jena, 1899. 



3 For experiments bearing directly on this question, see Gallardo, " Interpretacion 

 Dinamica de la division Cellular," Buenos Ayres, 1902. Reviewed by M. Hartog 

 in Nature, Vol. 67, 1902, p. 42. 



