128 CORAL AND ATOLLS 



of fact, there is no species of coral in this atoll that is not 

 able to withstand an exposure of many hours to the midday 

 sun, with from 6 inches to a foot of its apical growth above 

 the water : there is no barrier species that does not normally 

 suffer this at midday spring tides. There are many isolated 

 rocks that are ordinarily exposed for two feet at low tide, on 

 which living corals flourish luxuriantly. When season and 

 winds combine to cause tides abnormally low, it is possible to 

 go from island to island along the barrier flats, and for the 

 greater part of the journey to walk in but a few inches of 

 water ; and if such a walk be taken during a low tide at hot 

 midday, the smell of the exposed coral is almost overpowering 

 and may be noticed far out in the lagoon. Coral has an odour 

 that is peculiarly oftensive when the growth is exposed to the 

 air, and this strange odour is no sign of death, for a stinking 

 coral when replaced in water or when re-covered . by the 

 rising tide, flourishes again. At such a low tide the barrier 

 flats present a picture of bushes and boulders of living 

 coral all freely exposed to the sun, all dry, all smelling very 

 offensively, and yet the returning tide finds them all living as 

 actively as when it left them. A coral may be taken from 

 the bottom of the lagoon, may spend the best part of a hot 

 day, high and dry, in the bottom of a boat, and yet, when it 

 is replaced in the water, all its zooids will expand, and it will 

 resume all its vigour. Exposure to the sun and air between 

 tide limits plays but little part as a causative factor in the 

 question of coral death. Of course no coral could grow beyond 

 the normal high-tide level, but the remarkably level appear- 

 ance of the barrier flats is not the result of the action of sun 

 and air on the coral colonies so much as of the levelling 

 effects of the waves, and the moving fragments which they wash 

 to and fro. It is the grinding action of the surface waters at 

 their level of maximum activity which determines the limiting 

 level of upward coral growth, far more than the death of the 

 apices from the effects of sun and air. The waves that sweep 

 over the flats, and carry shorewards the fragments which they 

 have broken from the seaward margin of the barrier, are for 



