374 



Wuist: Branched prothallia 



wall where the light conditions were good and the prothallium 

 was not crowded by other prothallia. Fig. 9, A, shows a young 

 branched prothallium of about twenty cells, which had formed a 

 filament of three cells in the usual manner before the expanded 

 portion of the prothallium developed. The second cell of this 

 filament gave rise to a filamentous branch of three cells; the ter- 

 minal one of which divided by two oblique longitudinal walls to 

 form the beginnings of an apical cell. From the first cell of the 

 branch was cut off laterally a cell which would later develop into 



Fig. 9. Branched prothallia of Asplenium Filix-femina (L.) Bernh., X 75- 



another branch. The expanded portion of the prothallium also 

 gave rise to a short filamentous branch of two cells. 



In Fig. 9, B, a short filament of three cells was first formed by 

 transverse divisions, then the third cell divided in such a manner 

 as to form the beginnings of an apical cell. In the meantime a cell 

 was cut off laterally from the first cell of the filament. By trans- 

 verse and longitudinal divisions this branch developed becoming 

 two cells in width and forming at the apex the beginnings of an 

 apical cell. An extreme case of branching is shown in Fig. 9, C. 

 A filament of three cells formed in the usual manner. From the 



