Table 1. Concentration of halimedatrial and epihalimedatrial in 

 newly developing segments of Halimeda incrassata as a 

 function of time of day. Because we know little about 

 their biosynthesis and because their structures differ only 

 stereochemically, these compounds were combined to produce 

 Figures 6 and 7. 



HALIMEDATRIAL EPIHALIMEDATRIAL 



% of Ash-Free Dry Mass % of Ash-Free dry Mass 

 (N) X + 1SE X + 1SE 



A 

 Time 



2000 hr (4) 2.2+1.0 



0000 hr (3) 1.0+0.3 



0400 hr (3) 1.8+1.0 



0800 hr (5) 1.2+0.4 



1200 hr (2) 0.8+0.2 



1800 hr (2) 0.2+0.1 



Old (16) 0.2 + 0.2 



B 



Segment Type 



Tips (10) 1.7+0.5 1.6+0.3 



Young (9) 0.8+0.2 0.8+0.2 



Old (16) 0.2 + 0.0 0.1 + 0.0 



384 



