For comparisons of radioactive counts, the areas previously occupied by- 

 polyps were measured in all samples by tracing on to stiff cards which 

 were then cut out and weighed. Plastic film was used for samples of 

 irregular shape . 



RESULTS 



Data from the coral head checked for uniformity of labeling appear in 

 Table 1. The standard deviation represents approximately + l8^ of the 

 mean value for the radioactivity per cm of coral surface." The total 

 radioactivity extracted from triplicate samples of M. annularis and S. 

 siderea taken over a period of 11 days after exposure to Na COo was" 

 converted to counts/min/cm of surface and plotted against time in 

 Figures 3 and k. The figures also show counts in the alcohol and the 

 Mill OH extracts. 



Table 1. Labeling of coral head: a check on the uniformity of labeling. 



Siderastrea siderea was labeled with NaHl^C03 (i+OuCi) as describ- 

 ed and then sectioned according to the diagram (Figure l) . 



Sample Counts per min per sq. cm. of surface 



1 33,200 



2 32,700 



3 31,650 

 1+ 21,200 



5 30,800 



6 25,200 



7 27,000 



8 33,500 



9 25,950 



10 21,300 



11 19,700 

 Standard Deviation + i+,870 



VI-252 



