104 Wisconsin Academy of Sciences, Arts and Letters . 
EXPLANATION OP PLATE VIII. 
The figures of this and the following plate were drawn with the aid 
of the camera lucida, the magnification about 1,700 diameters in each 
case. All figures are from spore mother-cells of Marsilia quadrifolia. 
Fig. 1. Young spore mother-cell, showing characteristic aggregation 
of chromatin at central part of nucleus. 
Fig. 2. Somewhat older spore mother-cell, showing an elongated, 
vacuolar region in the cytoplasm at a. 
Fig. 3. An approximately full-sized cell; aggregation of starch 
grains on the side of the nucleus facing the sporange wall. 
Fig. 4. Synapsis; the chromatin strands oriented on a nucleole ly¬ 
ing close to the nuclear membrane. 
Fig. 5. Post-synapsis: the chromatin strands lying on the side of 
the nucleus opposite that occupied during synapsis. A fairly well-de¬ 
veloped bipolar figure of fibers in the cytoplasm, an indication of a 
third pole at the lower left corner. Most of the starch mass is in the 
next section. 
Fig. 6. Two cells in approximately the same stage as the preceding. 
In one of them a granule simulating a “centrosome.” 
Fig. 7. A later stage, showing unsymmetrical arrangement of the 
cytoplasmic fibers; a number of cone-shaped groups lie at the lower 
left corner of the cell below those shown in the figure. A considerable 
number of starch grains lie above the plane of the drawing. 
Fig. 8. Diakinesis. 
