Mature Halimeda 



\ 

 Microgamete 



Mature Halimeda 

 Macrogomete 



ZYGOTE 



PROTOSPHERE 



7 months 



2 weeks 



JUVENILE FILAMENTS 

 1/ 



5 months 



One large nucleus approximately 7-10 ji.ni 

 in diameter; > 500 lenticular chloroplasts 

 with starch grains; no amyloplasts; 100-150 

 Jim in diameter. 



Erect, positively phototrophic filamentous 

 extension approximately 30 jim in diameter; 

 nucleus divides forming regular-sized nuclei; 

 chloroplasts lose starch and are the shape o 

 a rice grain. 



Negatively phototrophic filamentous ex- 

 tension developed at opposite end to other 

 extension ; first amyloplasts appear. 



Filaments approximately 2 cm tall and 90— 

 1 30 (i,m in diameter in five months ; some erect 

 filaments have dichotomous or trichotomous 

 branching at their tips; creeping filaments 

 proliferate with some branches becoming 

 erect. 



Fig. 68. Scheme of development, in culture, of zygote of Mediterranean tuna over one 

 year, indicating morphological and cytological characteristics of protosphere and 

 juvenile filament stages. The ixiature Halimeda thallus has not yet been obtained 

 from zygotes in culture. (Adapted from Meinesz, 1972b, 1973.) 



