PLATE 46 

 Ectocarpus socialis S. and G. 



Fig. ]2. A small group of plants showing rhizoids, a few cells with chro- 

 matophores, and the positions and shapes of the zoosporangia. X 125. 



Fig. 13. A selection of parts of filaments showing the positions and relative 

 shapes and sizes of the gametangia. X 125. 



Ectocarpus cylindricus f. codiophilus S. and G. 



Fig. 14. A group of young plants showing both zoosporangia and game- 

 tangia, the two parts of ramuli on the left representing these organs on the 

 same plant. X 60. 



Ectocarpus Taoniae S. and G. 



Fig. 15. A portion of a creeping filament showing erect filaments and the 

 positions and relative shapes and sizes of the gametangia on both the creeping 

 and the erect filaments. X 250. 



Ectocarpus affinis S. and G. 

 Fig. 16. Diagrammatic representation of a small group of plants on their host. 

 Fig. 17. Portions of filaments illustrating positions, relative shapes and 

 sizes of gametangia. X 225. 



[420] 



