Allen—-Sper mat o genesis and Apogamy in Ferns . 29 
Although there is a broad, connection between the two, each nu¬ 
cleus has retained to a large extent its individual contour. The 
zone where the two nuclear membranes are in contact is marked 
by a deep furrow. A number of the fine strands of chromatin 
run through from one nuclear cavity to the other. There is a 
dense tangle of threads between the two. Many of the chroma¬ 
tin strands in the nucleus at the right, run radially inward 
toward the opening, suggesting perhaps the idea of motion to¬ 
ward the chromatin of the other nucleus. In a half dozen 
places the chromatin threads are already paired for a short dis¬ 
tance. 
In figure fifty, we have another characteristic fusion figure. 
Here, as in figure forty-eight the fusion in the nuclei is the 
more advanced. A rather deep furrow still partially separates 
the two masses of cytoplasm. The plasma membranes of the 
two cells are continuous but at the plane of junction of the 
nuclei a furrow extends in almost to the nuclear membrane. 
The fusion nucleus is well rounded. A protruding ridge in 
the outline along the upper side is the only remaining evidence 
of fusion so far as form is concerned. Within the nucleus the 
strands of the spirem run more or less continually from one 
end of the nucleus to the other. Here, too, in a few places the 
chromatin threads are paired. Two or three small nucleoles 
are present 
That the fusion is always in pairs and that all the sixteen 
mother cells fuse in the above described fashion is further estab¬ 
lished by the number of sporogenous cells in the spore sac be¬ 
fore and after the fusion process. 
The stage during which sixteen spore mother cells are pres¬ 
ent in the spore sac is apparently short. The fusion stages are 
next found abundantly. The growth of the cells continues dur¬ 
ing fusion and when the spore mother cells reach their full size 
and round up, only eight are to be found in a sporange. 
This second eight-celled stage is markedly different from the 
first eight-celled stage described above. The spore sac has now 
increased greatly in size. The tapetal cells are shrunken and 
crushed and often out of place. The spore mother cells are more 
or less rounded up and separate from each other. The nucleus 
