218 



Mr Gardiner, On the Rate of Growth 



imagined as flat plates, covering the same horizontal areas, as 

 the specimens themselves naturally covered when alive. 



Name of Coral 



Time of 

 Growth 

 in Days 



First 

 Weight 



in 

 Grams 



Present 

 Weight 



in 

 Grams 



Weight 



in 

 Water 



in 

 Grams 



Specific 

 Gravity 



Volume 

 in c.c. 



Thick- 

 ness as 

 a Sheet 

 in mm. 



1. Stylophora 



raristella, var. 



wilsoni 



1030 



310 



293 



104 



1-55 



189 



14-1 



2. Stylophora 



raristella, var. 



wilsoni 



1030 



186 



168 



53 



1-46 



115 



12-8 

 122 



3. Pocillopora 

 suffruticosa 



1030 



194 



190 



106 



2«26 



84 



4. Pocillopora 

 suffruticosa 



1030 



131 



127 



71 



2-27 



56 



10-2 



5. Pocillopora 



plicata, var. 



aspera 



1030 



195 



177 



57 



1-47 



121 



24-7 



In examining the table, the difference between the specific 

 gravities and volumes of the two species of Pocillopora is most 

 noticeable. Assuming that the corallum is an excretion, it 

 would naturally be supposed that the greater the surface the 

 quicker the rate of growth. Yet the reverse here is the case, 

 P. plicata being a fairly massive species, while P. suffruticosa 

 branches into fine twigs. It is not known, however, when the 

 larvae affixed themselves, and the real time of growth is pro- 

 bably in every case very much less than the recorded time. 



For comparison the last column is the most important, but 

 it assumes that the position of growth, the vertical and hori- 

 zontal axes, are known. It is necessary hence that these should 

 be marked (by paint, or some other means), when the specimens 

 are obtained. This is more especially the case with massive 

 than branching species. All true reef corals grow towards the 

 light, and with branching specimens of any size, remembering 

 that the ends of the central larger branches will be approxi- 

 mately vertical and that the underside has only short blunt 



