368 BOTANICAL GAZETTE [DECEMBER 
masses eleven are clearly double. Whether in the case of the 
larger numbers all the groups represent pairs, or whether some 
of them are single chromosomes, has not been determined. It 
is by no means certain, however, that the number of chromo- 
somes in the equatorial plate is so constant as theories of nuclear 
division which are accepted at the present time require us to 
assume. 
There is a corresponding development of the spindle fibers 
coincident with the maturation of the chromosomes. The spindle 
acquires a more distinctly bipolar form, and its fibers, which 
become coarser and longer, run continuously from pole to pole. 
During the prophase they have the appearance of knotted cords 
or strings of loose beads. These features can be seen in fig. 5, 
and also in fig. 6, which represents a section of a cell cut suffi- 
ciently deep to remove one chromosome and part of the equato- 
rial region of the spindle. But in the metaphase and anaphase 
the knotted appearance is no longer recognizable. The fibers 
then appear as stout uniform threads or rods ( figs. 9, 70). The 
same statement can be made of the second division ( figs. 17 
78); that is to say, the fibers at the time when they are aed 
tioning in the separation of the chromosomes are of uniform 
diameter and texture. They are rows of granules at all other 
times, either when they are disappearing or in process of forma- 
tion. 
It is evident that the achromatic spindle is wholly of 
plasmic origin. If any nuclear material takes part in its formation 
it can do so only after passing through the nuclear membrane 
There can be no direct union of linin or other nuclear substance 
with the kinoplasm, for in nuclei, as far advanced in the prophase 
as those shown in jigs. 5 and 7, the chromosomes are the ee 
Stainable constituent remaining; no fibers of any kind can 
made out, nor any trace of the nucleolus. : 
A comparison of the shape of the spindle, 
before and after the dissolution of the nuclear membrane 
gests that this period is marked by a sudden change- 
the nuclear membrane is still present, the spindle has - 
as seen just 
, sug 
While 
poles 
