656 Wisconsin Academy of Sciences , Arts, and Letters. 
DESCRIPTION OF FIGURES 
All figures were drawn with the aid of a camera lucida. 
Figures 1 to 35 inclusive have an approximate magnification 
of 2000 times; figures 36 to 46, 600 times; and figures 47 to 
58, 150 times. 
Plate I. 
Figure 1. Resting nucleus immediately preceding the last pre- 
synaptic division in the anther. 
Figure 2. Late prophase of the last pre-synaptic division 
Polar caps formed as in typical divisions. 
Figure 3. Equatorial plate stage of the last pre-synaptic di¬ 
vision. 
Figure 4. An early telophase stage immediately preceding 
synapsis. The general location of the chromosomes 
can still he seen. 
Figure 5. The resting nucleus of the pollen mother cell. 
Figure 6. A tangential section of the resting nucleus of a 
pollen mother cell showing chromatin knots and the 
finer connecting strands. 
Figure 7. The nucleus of a pollen mother cell in the early 
prophase stage. The net like appearance is becom¬ 
ing transformed into more uniform and continuous 
threads while the chromatin material is drawing away 
from the periphery of the nucleus. 
Figure 7a. A tangential section of the nucleus shown in Fig. 
7. The fine spirem is seen here to be w^ell formed 
with no trace of knots and connecting strands. 
Figure 8. Tangential section of another nucleus in the same 
stage of contraction as Fig. 7. The leptoneme condi¬ 
tion conspicuous. 
Figure 9- A tangential section of a nucleus in very early pro¬ 
phase. There are fewer connecting strands and the 
chromatin knots are more elongated than in the rest¬ 
ing nucleus. 
