348 SCIENCE PROGRESS 



sphere in the most powerful electric field. Gallardo was the 

 first to note this, and the publication of Vejdowsky and Mrazek's 

 figures have given the most striking confirmation to his theoretical 

 anticipations. The gebildete Laier is so accustomed to the idea 

 that the movable plates of an electrostatic field, the equally 

 movable (though inseparable) poles of a magnet are the sources 

 of the energy of a field, that it was natural to apply this 

 inadequate conception to the cell-field in Metazoa, and to hold 

 to it even after it became clear that it could not apply to Higher 

 Plants. But the physicist will have no difficulty in accepting the 

 view that the stresses of the strain-field are correlated with its 

 condition of strain, and that the centrosomes are merely sources 

 of supply of highly permeable material to hold and to convey 

 that strain. 



Finally, we must regard the processes in the mitotic cell-field 

 as due to the combination of many factors. We may summarise 

 them thus : 



i. Mitokinesis is the expression of a dual strain-force, acting 

 in a viscid heterogeneous medium, of which the more permeable 

 constituent segregates out into chains of force, grouped into 

 spindle and asters. 



2. The centrosomes are infinitely permeable to mitokinetism. 

 They are centres of like osmotic phenomena, probably con- 

 ducing to the growth of the archoplasm of the chains of force. 



3. Nuclear wall and cytoplasmic boundary are also highly 

 permeable to mitokinetism. 



4. The functions of the centrosomes are (i) to afford fixed 

 points for the spindle ends; (ii) to provide for the growth of 

 kinoplasm. 



5. Ordinary cytoplasmic motion explains the growth of the 

 spindle and the progressive divergence of its ends. 



6. In the completion of the splitting of the chromosomes 

 and the discession of the daughter halves, they behave exactly 

 like flexible inductors suspended in a viscid medium in a magnetic 

 field. 



7. Mitokinetism is the force which determines the partitive 

 division of the formed contents of the nucleus. 



8. Polyasters, even with an odd number of centres, may occur 

 in the fields of a dual force. 



9. No theory of like forces at the centres of the cell-field will 

 account for the typical spindle. 



