Nature of the attractive force 81 



other figures thus. " The mitotic forms have often been compared 

 (Fol, Ziegler, Gallardo,) to lines of force in an electric or magnetic 

 field, but this has not furnished any deeper analogy; in contrast 

 to the electric and magnetic figures with dissimilar poles we are 

 dealing in the case of mitosis with similar poles; this may be 

 recognised from the migration of the chromosomes in opposite 

 directions, and still more clearly from the association of several 

 poles to form figures which do not in any way disturb the spindle 

 and aster figures. The crossing of the rays has been urged as an 

 objection to this comparison." 



Przibram clearly favours a solution of the problem along the 

 line of differential hydrostatic states, the accumulation and with- 

 drawal of water from various parts of the alveolar protoplasm and 

 he suggests as "a provisional solution of the difficult problem 

 of mitotic cell division" the following statement: "The common 

 cause of the mitotic phenomena lies in a localised secretion 

 ('condensation') of a more liquid substance, the Enchylemma, 

 and in the transformation, caused by the redistribution of the 

 liquid, of a monocentric system of surface tension into a dicentric 

 system." 



Przibram does not allude to the paper by Marcus Hartog in the 

 Proceedings of the Royal Society, 1905, Vol. LXXVI, where that 

 author meets at any rate some of the objections alluded to above, 

 such as the anastomosing and crossing of the rays, which he finds 

 actually were reproduced in his magnetic model. 



Hartog also obtained, though not very perfectly, triaster and 

 tetraster conditions, although working with unlike poles of the 

 magnet and a "third of zero sign in the models the core of a 

 magnet without a coil." 



Still, these experiments, although they tend to make the 

 analogy between this force of the dividing cells [termed "karyo- 

 kinetic force," or " mito-kinetism " (Hartog)] closer, leave the 

 analogy an analogy only, indicating that the effect upon cell 

 material is in its action from a centre similar to that of a force 

 like magnetism or electricity on substances variably permeable to 

 those forces acting in a field from a centre. 



Whatever the nature of the force may be, if it act under those 

 conditions from a centre, analogous effects may be produced quite 



