486 Mr Gardiner, The Coral Reefs of [Mar. 7, 



to one proportionately poor — so as to observe them constantly and 

 have them handy to kill, when they were properly expanded. I 

 fixed them between stones on the sandy bottom, but they soon 

 became silted up with sand and were killed. I then placed a 

 number of pieces on the hollowed out top of a species of Astrwo- 

 pora, but debris soon collected round them, and, when I last visited 

 them, I found only the clean coralla without polyps. Generally I 

 could not, in the boat channel, get any true coral to grow if placed 

 on the bottom owing to the sand and mud deposited on them, but 

 all would grow if not too near the passages, on the tops of the 

 stone heaps, which are built up by the natives for fish trapping. 

 In the few fringing reefs, with boat channels, which I examined, in 

 Fiji it was unusual to find any corals growing inside the reef, and 

 at Rotuma the presence of corals is largely due no doubt to the 

 presence of these stone heaps, on which the larvae fix themselves 

 above the level of the scour of the tide. 



When I saw that the corals on the Astrmopora were being 

 killed, I tried transferring all the commoner species out of their 

 own peculiar zones into other zones. I also wounded a certain 

 number of corals over a definite area to see how soon their wounds 

 would heal and be grown over. Of course in the limited space of 

 three months no decisive experiments could be carried out, the 

 results are yet not without interest. Broken-off arms of branching 

 species and small pieces of massive species all died. .Branching 

 forms removed by the root and large blocks of massive species, if 

 kept in their own proper zone, continued to live. Corals could be 

 removed from the rim to the reef-flat ; from the nature of the reef 

 it was impossible, however, to try the opposite experiment. Some 

 species from the reef of Pocillopora and Prionastrcea, fixed on the 

 top of a stone heap near one of the passages, seemed to flourish, 

 but species of Madrepora and most other genera died. In no case 

 was there any sign of the coral attempting to fix itself. The polyps 

 near the damaged part of a colony died, and there was no attempt 

 in the time to heal over the scars, which simply gave an easy 

 entrance to boring animals. The experiments with Millepora and 

 Heliopora were inconclusive ; their lamellae fixed on the hollowed 

 out top of the Astrceopora certainly seemed alive after three 

 months. 



I never saw the corals over any considerable area, or individual 

 corals, killed by the heat of the sun at low tide. The corals on the 

 rim, at even the lowest tides, are constantly wetted by spray, and 

 on the reef-flat the water remains constant in height. In the boat 

 channel at Rotuma, and on certain shoals at Funafuti, I noticed 

 species of Montipora, Porites, Favia and many other genera exposed 

 for upwards of three hours at low water without any effect on them. 

 Nearly, if not all, had some part in the water, and doubtlessly 





