196 Farmer and Digby.—On the Cytological Features exhibited by 
evident, and not before, the kinoplasmic sheath already described is 
observed to protrude from the surface of the nucleus at these points. In 
this way the quadripolar structure is initiated. The inference that it arises 
as the result of a specific influence attributable more or less directly to the 
chromatic linin seems irresistible. The lines of kinoplasm assume curvatures 
which unless one is careful may easily lead to misinterpretation. In surface 
view the appearance is sometimes such as to suggest the existence of a so- 
called ‘Hermann’s Spindle’; owing to the fact that in the regions between 
the cones the fibres form curves which start from the surface of the nucleus 
(cf. PI. XVI, Fig. 7, to the left). 
Instances also occur where individual threads of the spindle are 
attracted towards, or perhaps originate from, isolated granules in the cyto¬ 
plasm ; but in this fern, whatever the individual differences may be, 
a quadripolar (or multipolar) spindle is the rule. We have also found 
it to occur in the premeiotic archesporial divisions, though not so obviously 
as at meiosis (PI. XVI, Fig. 6). 
The cones consist each of a dense sheaf of fibres, and these are very 
‘ rigid ’ in character, as is shown by the fact that a cone may often be seen 
to cause a bulging out of the cytoplasm (Fig. 7) at the periphery when, 
through the action of reagents employed in fixing, the cell protoplasm 
has contracted away from the wall. This ‘ rigidity ’ has been observed 
before and in other plants, and it has been interpreted as the result of 
a ‘ growth ’ of the fibres. We do not share this view of the matter, at least 
if the word growth is to bear its ordinary meaning ; but, as we have 
already indicated, the whole process seems to us to depend primarily upon 
repulsive forces developed within the cell. We think the facts support the 
view that electrical disturbances, and perhaps also phenomena of induction, 
play the most important part in the formation of these structures, 1 and whilst 
they are normally maintained by the continuance of those conditions that 
were in the first place responsible for their formation, it by no means follows 
that the cones, when once organized, will lose their identity immediately on 
the cessation of the operation of the causes which first produced them unless 
the new conditions are such as to actively render-their further continuance 
impossible. 2 We have used the term c kinoplasm ’ as designating a par¬ 
ticular differentiation of the cytoplasm, but we make no assertion as to 
whether the stuff which this differentiation renders visible really represents 
a specific substance or not. It is of course easily conceivable that such 
a substance might exist, but would only become visible, would only become 
organized, when appropriate conditions were supplied, just as the figure 
1 Lillie, R. S., Am. Journ. Physiol., viii; also Biol. Bull., iv. See also Gallardo, A., L’inter- 
pretation bipolaire de la division karyocinetique. An. del Mus. Nacionale de Buenos Aires, t. xiii, 
1906. 
* Hartog, M., The dual force of the dividing cell. Proc. Roy. Soc., B. 76. 
