
1904. | The Dual Force of the Dividing Cell. 565 
The fact is that the etymological meaning of “ karyokinesis ” (= disturbance 
of the nucleus) forbids its correct application to the dual force we have 
investigated. For this reveals itself first in the cytoplasm, while the nuclear 
wall is still intact, and since this wall is highly permeable, it must act 
as a screen between its contents and the force in the cytoplasm, just like 
a spherical investment of charcoal-iron would screen all within it from 
external magnetism. 
If by a permissible extension of meaning we use Aaryokinesis as an 
inclusive term to designate all the phenomena of “indirect cell-division,” 
we find that this covers not only the cual force, but the forces that separate 
the poles, and possibly others as well, for the process is not a simple one. 
Henee, for this dual force under which the cytoplasm gives rise to chains 
of foree in the form of the dumb-bell figure, comprising spindle and asters, 
we have had to use the term “ mitokinetic,’ signifying the kinesis which 
reveals itself by a thread-structure. 
Summary. 
1. The cytoplasmic figure of the dividing-cell is a strain-figure, under 
the action of a dual force, analogous to magnetism, and still more to statical 
electricity ; without prejudging its nature further we may call it “ mito- 
kinetic force” or “ mitokinetism.” 
2.. The conception of relative permeability is invoked for the first time 
in elucidating the behaviour of this dual force in comparison with those of 
magnetism. 
3. By comparison with magnetic models we find that (a) the spindle 
fibres and astral rays, (b) the Hautschicht of the cytoplasm, (c) the nuclear 
wall, and (d) the free chromosomes along the cell-spindle must all be of 
high permeability to mitokinetism as compared with the other structures of 
the cell (see also 7, 12, 14).* 
4, As the cell-structures are all material, the conception of geometrical 
lines of force is inadequate to explain them. We must recognise that the 
effect of stresses within a mixture of substances which are of different 
permeability and free to rearrange themselves, will be to segregate out the 
more permeable material in strands along the lines of force whose distribu- 
tion they modify. Such strands we may call “material chains of force,” or 
for brevity simply “ehains of force.’ It is only our recognition of these 
structures that enables us adequately to utilise electric and magnetic models 
for our explanations. 
* [3a. The periphery of the centrosome is also highly permeable, since it screens the 
alveolar contents from the action of the surrounding field (see fig. 4).—Note added during 
printing. | 
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