28 Wisconsin Academy of Sciences, Arts, and Letters. 
ing both before and after fusion. The fusion may take place 
early, in which case as in figure forty-six, the fusion cell is 
small. On the other hand, the fusion may be delayed until the 
cells are half grown. The fact that the stage when fusion be¬ 
gins, varies both in different spore sacs, and to some extent in 
the same spore sac, accounts in part for the abundance of these 
stages in sections through the young sori. 
In figure forty-seven, the cytoplasm of the two cells is shown 
completely united. It is to be noted, however, that at the mid¬ 
dle of the right hand side, where the union is most recent, the 
line of union is still traceable by the openness of the cytoplasmic 
mesh-work and the large vacuoles. In the nuclei the fused 
region is much broader than in figure forty-six and the chro¬ 
matin reticulum of the two is continuous. Ho nucleoles were 
present in this case. 
Figure forty-eight represents the type of fusion figure encoun¬ 
tered most frequently. I have recorded not less than forty like 
it. Some of these are smaller than the one drawn and a few are 
larger. The condition of the chromatin varies in the different 
cases from that of a reticulum to that of a well-defined spirem. 
In all cases, the nucleus has the characteristic kidney shape, 
and the cytoplasm of the two cells is completely fused around 
the convex side of the fusion nucleus, but remains separate 
almost to the nuclear membrane on the concave side. 
Just why the cells and nuclei should fuse and round out more 
quickly on one side than on the other is hard to understand, 
but in the majority of cases the fusion plainly occurs in this 
fashion. These figures are not oriented in any particular way 
in the sporange. In some, the convex side of the nucleus is 
turned toward the sporange wall, while in others the concave 
open side is turned outward. 
Figure forty-nine represents a more unusual type of fusion. 
The cell here is almost full grown. The cytoplasm of the two 
is completely fused. [Neither the contour of the cell nor the 
appearance of the cytoplasm gives any evidence that a fusion 
has occurred. The nucleus on the other hand still shows clearly 
its double nature. In fusing, the two component nuclei evi¬ 
dently came to lie side by side and flattened against each other. 
