34 Wisconsin Academy of Sciences, Arts, and Letters . 
the cell is much less dense. The spindles themselves are usually 
broadpoled and the chromosomes are short and thick. 
At the close of the second division the daughter nuclei are 
formed and the chromatin goes into the form of a reticulum. 
Central spindles are then formed connecting all four muclei in 
preparation for cell plate formation. Figure fifty-nine shows 
a stage in this process. Only two of the four nuclei lie in the 
plane of the drawing. The volume of all four taken together 
is considerably less than that of the fusion nucleus before di¬ 
vision. These four nuclei are irregular and angular in outline. 
The rather scanty chromatin is in the form of a loose irregular 
network. At this stage numerous fibres are seen running 
radially from almost the entire surface of every nucleus. The 
only side of each nucleus that is free from fibres is that lying 
toward the mother cell-wall. This space between the nuclei 
and the mother cell wall is filled with vacuolated cytoplasm. 
Many of the fibres can be followed through their entire length 
from one nucleus to the other. They are uniformly distributed 
throughout the space between the nuclei. In the middle plane 
between each pair of nuclei, thickenings in the fibres are formed. 
They do not as yet touch each other and are still placed a little 
irregularly. This is the beginning of cell-plate formation. 
With the formation of the cell plates, the spore mother cell 
is divided simultaneously into four approximately equal cells. 
Figure sixty represents a section through a tetrad of young 
spores. Only three of the four spores lie within the plane of 
the drawing, and the middle one of the three is not seen in me¬ 
dian section. The four cells lie loosely connected—spaces ap¬ 
pearing between them. Each young spore is a somewhat elon¬ 
gated cell whose surfaces of contact with the other spores are 
still flat but whose free surface is convex. The nucleus also 
is elongated following more or less the contour of the mother 
cell. The chromatin is more conspicuous than it was in the 
stage shown in figure fifty-nine and forms a dense reticulum in 
which there are comparatively large aggregations. 
As mentioned before, the number of spores formed in a spore 
sac never exceeds thirty-two. Eight spore tetrads is the maxi- 
