238 KrrKwoop: PoLLEN-FORMATION IN CUCURBITACEAE 
4. The spindle originates partly from the linin of the nuclear 
reticulum but mostly from the thin weft of fibers which appears 
about the nucleus as its wall is gradually dissolved. As the form 
of the nucleus changes from spherical to angular the spindle-fibers 
are collected into numerous pencils pointing different directions. 
These gradually collect to form a bipolar spindle which stands in 
the center of the large mother-cell and has no apparent connec- 
tion with the plasmatic membrane. The form of the spindle is 
narrow and sharply pointed, some of its fibers Spreading far out 
into the cytoplasm. 
5. The chromatin in early stages in the development of the 
spore-mother-cell is inconspicuous, but as the time for division 
approaches it becomes distributed in paired masses through the 
nuclear reticulum. The masses are regarded as representing 
chromosomes. They finally become merged into a compact mass 
as synapsis approaches. 
6. Synapsis here seems to be a normal phenomenon in the life 
of the cell. The chromatin becomes massed about the nucleolus 
at one side of the nuclear vacuole. From this condition it merges 
from a coiled thread split longitudinally, which soon segments 
into sixteen double pieces. These pieces become compactly 
massed at the equator of the spindle, contracting into rounded 
masses. The separation of the chromosomes is according to the 
heterotypic form of mitosis, The reduced number of the chro- 
mosomes is sixteen. 
7. In the telophase of the first division the chromatin forms a 
thread which is gradually dissolved into small granules and masses 
almost as in the resting nucleus. The second mitosis is inaugu- 
rated by the reassembling of this chromatin into irregular masses, 
which become more evenly rounded and divided into two in the 
ensuing metaphase. Owing to the size and rounded form of the . 
chromosomes, the characters of a homotypic mitosis were not 
discernible, but the appearance of the figure is essentially differ- 
ent from that of the first mitosis. In the telophase of the second 
division the chromatin distributes itself in the form of a beaded 
network which persists long into the development of the spore. 
SYRACUSE UNIVERsITY. 
