PLATE 19 



Fig. 1. Young erect filaments. To the left, premature formation of spo- 

 rangia; to the right the raeristematic zone is clearly seen; X 480 diam. 



Fig. 2. Solitary lateral branch, resembling an Ectocarpus sporangium, X 240 

 diam. 



Fig. 3. Three sterile cells showing disk-shaped chromatophores, X 480 diam. 



Figs. 4-5. Parts of fertile filaments with lateral branches, X 240 diam. 



Fig. 6. Mature plurilocular sporangia, X 480 diam. » 



[164] 



