Fig. 3. The constructional unit of Halimeda is the coenocytic filament. In segments, 

 in contrast to holdfasts, there is a definite pattern of organization which is least 

 complex in H. cryptica, a species with a single main filament. This central medullary 

 filament branches several times, producing lateral branches which also branch. 

 In most species there are several to many medullary filaments. Scale bar is 

 1 mm. Material is stained with dilute Lugol's solution, and mounted in glycerine. 

 (From Colin vaux and Graham, 1964.) 



