IN THE POLYPODIACEAE 379 
branch at one side of the apex. Fic. 13, C, shows the origin of a 
branch from the apex of the expanded portion of the prothallium, 
while Fic. 13, D, E, shows further development of such a branch. 
These branches formed a small plate of cells, two rows in width, 
then tended to revert to a filamentous condition, at the same 
time growing downward, thus giving the appearance of two young 
prothallia attached by their apexes. FIG. 13, F, shows the only 
case of dichotomous branching which was observed. . One of the 
branches reverted from a plate of cells to a filament four cells in 
length. 
Woodwardia virginica (L.) Sm.—The branched prothallia of 
<P 
se 
Fic. r4. Branched prothallia of Woodwardia virginica (L.) Sm. A, D, X 125; 
B,C, x4. 
Woodwardia virginica varied in size and shape and showed a 
decided tendency to branch dichotomously. Those shown in 
Fic. 14, A-D, and 15, E, F, developed on the inner surface of 
the pot wall of the soil culture. They were not crowded by other 
prothallia and were well lighted. Fic. 15, G, developed on Prantl’s 
nutrient solution with CaSO, omitted. In Fic. 14, A, B, branching 
e first and second cells of the filament. In 
took place from th 
place after the plate of 
Fic. 14, C, D, and 15, G, branching took 
