302 Allen . — The Early Stages of Spindle- Formation 
All of my observations are opposed to the notion that the 
kinoplasmic fibres are only { lines of force,’ or that they are, 
as Farmer (’95 b ) expresses it, simply hyaline protoplasm 
which has become strained along such lines of force. The 
appearance of the fibres throughout their history, their stain- 
ing properties, their powers of movement and contraction, all 
set them off as distinct from the surrounding cytoplasm, and 
argue in favour of their chemical and physical differentiation. 
The well-known formation of asters about the blepharoplasts 
points in the same direction ; for the same organs later form 
cilia which certainly closely resemble, if they are not essen- 
tially identical with, the intracellular fibres. Farmer (’95 b , 
p. 475) found that the fibres of the polar aster in Fossombronia 
extended as stiff projections beyond the broken edge of a cell 
which had been injured in cutting. In some preparations 
of my own of the dividing pollen-mother-cells of Lilium , 
there are numerous cases in which, after the first nuclear 
division and the formation and splitting of the cell-plate, some 
of the fibres of the central spindle may still be seen stretching, 
as densely stained strands, across the gap between the 
daughter-cells. Such facts appear consistent only with the 
actual existence of the fibres as differentiated structures. 
This specialized fibrous constituent of the cytoplasm seems 
to be, as has often been pointed out, the more active element 
of the cell ; the fibres in many ways display energy ; they 
change their position in the cell ; they bend and straighten 
themselves ; they extend into the nuclear cavity, are attached 
to the chromosomes, and appear to pull these bodies out into 
close proximity to the nuclear membrane ; when the latter 
disappears, the fibres arrange themselves into a figure of 
definite form, the bipolar spindle ; they apparently pull the 
chromosomes into the equatorial plate, and from this situation 
draw the daughter-chromosomes toward the poles. These 
activities suggest an analogy, if not a close relationship, 
between the fibres in question and the cilia of motile cells, and 
perhaps even a relationship with the contractile elements 
of muscle-fibres. Since, as has been . noted, there is no 
