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IV. 



ON THE PATH OF A SMALL PEEMEABLE BODY MOVING WITH 

 NEGLIGIBLE ACCELERATION IN A BIPOLAR FIELD. 



By PHILIP E. BELAS, B.A, A.RC.Sc.L, 



AND 



MARCUS HARTOG, M.A., D.Sc. (N.U.I.), 

 University College, Cork. 



(COMMUNICATED BY PROFESSOR WILLIAM BROWN, B.SC.) 



(Plate I.) 



[Read November 23, 1915. Published February 28, 1916.] 

 Historical. 

 This investigation originated in the researches of one of us (Dr. Hartog) 

 upon the " Mechanism of Mitosis in the dividing cell." Struck by the 

 similarity of the spindle form which is assumed by the achromatin fibres 

 of a cell undergoing division with that of inductive dust, when scattered 

 on a flat surface, or suspended in a liquid of lower permeability, between 

 two poles of opposite sign, he was led to develop a theory that at a 

 particular stage in its life-history the cell was the seat of a dual force, 

 like electrostatic, centring on two bodies — the centrosomes — whose field 

 was bounded by the cell wall. The chromosomes were to be considered 

 as portions of matter more permeable (in the broad Kelvin sense) than 

 the medium in which they moved and their orientations in the equatorial 

 plane, discessions and migration to the centrosomes were to be accounted 

 for by the differential action about the two force centres on these and on the 

 surrounding medium. 



This theory we consider to be fully established by the experiments 

 described in a series of papers by Dr. Hartog, and in this our joint paper. 



When we were attempting to model the phenomena of mitosis by means 

 of a bipolar magnetic field, we had to consider what would be the path of a 

 small disc of very soft iron if floated in a viscid liquid between the poles of 

 an electromagnet — the disc at no time acquiring observable acceleration. 



A more accurate model of the field of the living cell would be obtained 

 by using charged electric spheres ; but since climatic and other conditions 

 made electrostatic force inadmissible in practice, the plane section of the 

 magnetic field through the poles, having the same general distribution of 

 energy, was utilized by us. On looking up the literature of fields of force, 

 electrostatic and magnetic, we noticed a remarkable paucity of information. 



A single North Pole —that useful abstraction — would of course move along 



SCIENT. PROC. K.D.S., VOL. XV., NO. IV, F 



