T. F. GOREAU 285 



phuric and phosphoric acids as the primary ashing agent, we use 

 mixtures of 70% perchloric and concentrated nitric acids with a 

 bit of potassium iodate added. We cannot use sulphate in any form 

 because we wish to avoid converting the calcium to the sulfate 

 and phosphate salts. 



PHILLIPS: The 80% ethanol might be worth trying since it would 

 avoid the use of this rather explosive reaction mixture. 



GOREAU: We have had no trouble with it because we are 

 using only 300 mg. samples in which there is less than 20 mgs. of 

 organic matter present. 



HAND: Would you comment on the number of algae in the 

 growing tip as compared with the number farther away. 



GOREAU: Histological sections show fewer zooxanthellae in 

 the growing tip of A. cervicornis. The mg. N/mg. chlorophyll a ratio 

 is also much higher in the axial polyps than in the lateral polyps- 

 indicating a lower specific photosynthetic rate in the growing tip. 



HAND: This suggests that where there is less algae, there is 

 more calcification. 



GOREAU: Yes, at least in A. palmofa and A. cervicornis. 



