92 BOTANICAL GAZETTE | FEBRUARY 
the chromosomes are loosely arranged throughout; and the 
metaphase proceeds with separation of the daughter segments 
at the split previously indicated. In the anaphase, when drawn 
to the fixed pole, the chromosomes are arranged as if in close 
contact with the membrane adjacent. 
From the position of the microspore nucleus just previous 
to this division, it is to be noted that the spindle is further 
peculiar on account of its orientation in a plane perpendicular to 
the greatest mass of protoplasm. There is some evidence that 
the nucleus of the microspore constantly remains in the vicinity 
of that wall of the microspore which was in contact with the 
other spores in the group of four, yet certainly not in contact 
with this wall. Since this wall is usually in a plane perpendicular 
to the greatest mass of protoplasm, this may partially account 
for the constant orientation of the spindle. The free pole 
of the complete spindle occupies approximately the center 
of the spore, hence the axis of the spindle is about equal to 
half the short diameter of the spore. In this division the 
sudden disappearance of the large nucleolus is a matter of 
some interest, in connection with other observations previously 
given upon this organ. In some cases large fragments of 
nucleolar-like substance seem to be entangled in the fibers of 
the developing spindle, and in several cases a large mass of 
this material has been found at the free pole, and appat- 
ently held between the fibers.6 Moreover, in accordance with 
the observations of many others, I noticed only a few deeply 
staining granules in the cytoplasm previous to the disappearance 
of the nucleolus; but in the anaphase and telophase stages - 
division they are especially abundant in the vicinity of the free 
pole. They do not, however, disappear with the formation of 
the daughter nuclei, persisting for a time, but disappearing 
almost entirely before the pollen grain is mature. 
The general effect of the division of the microspore nucleus 
is well known, but some details may be mentioned, particularly 
6 " * 
DeBskt: Beobachtungen iiber Kerntheilung bei Chara fragilis. Jahrb. f. wiss 
Botanik 30: 227. 1897 
