IN THE POLYPODIACEAE 



377 



the origin of the branch from the first cell of the filament and Fig. 

 II, D, shows the further development of this branch into a fila- 

 ment of five cells. In Fig. ii, C, is shown an interesting example 

 of branching. Here the first prothallial cell instead of dividing 

 by a transverse w^all into two cells, divided by means of a longi- 

 tudinal wall, thus forming two cells side by side. One of these 

 cells by growth and transverse division continued the growth of 

 the filament while the other gave rise to two branches. One 

 formed a filament of two cells, the first of which was extremely 

 long. In Figs, ii, E, and 12, the branches were not formed until 



Fig. 12. A-E. Branched prothallia of Wood:>la obtusa (Spreng.) Torr., X 125. 

 F. Branched prothalUum of Phegopteris polypodioides Fee, X 75- 



the expanded portion of the prothallia had begun to develop. In 

 Fig. 12, the expanded portion later showed a decided tendency 

 to branch monopodially at its apex. 



Polypodium aureum L. — Only one case of branching was observed 

 in this species and it developed on the distilled water culture. As 

 shown in FiG. ii, G, the branch originated in the first prothallial 

 cell. The rate of growth was the same for both the main filament 

 and the branch. 



