378 



Wuist: Branched prothallia 



Woodsia obtusa (Spreng.) Torr. — All the cases of branched 

 prothallia of Woodsia obtiisa were observed on distilled water 

 cultures; in two cases branching was dichotomous while in the 

 other three cases it was monopodial. Fig. 12, B, shows the 

 branch originated from the first cell of the filament. In Fig. 12, 

 A, the branch originated from the slightly developed cell plate. 

 Fig. 12, C, D, shows different stages in the development of the 

 dichotomous branches. Fig. 12, E, was an interesting case of 

 branching. Here the wall which cuts off the branch from the 

 main filament did not form at the usual place, but formed almost 

 in the center of the filament cell which gave rise to the branch. 



Fig. 13. Branched prothallia of Scolopettdrium vulgare Sm., X 125. 



Scolopevdrium vidgare Sm. — All cases of branching in this genus 

 were observed on Prantl's solution with CaS04 omitted. Fig. 13, 

 A-E, shows typical examples of the types of branching found in 

 these cultures. Fig. 13, A, is interesting as showing the tendency 

 of both the second and third cells of the filament to form mono- 

 podial branches with very short cells. In Fig. 13, B, the branch 

 which originated from the third cell of the filament formed im- 

 mediately a plate of cells which in turn showed a tendency to 



