Sect. I. THE GROWTH OF CORAL-REEFS. 
87 
From these facts, it is certain, that the strongest 
and most massive corals flourish where most exposed. 
The less perfect state of the reef of most atolls on the 
leeward and less exposed side, compared with its state 
to windward ; and the analogous case of the greater 
number of breaches on the near sides of those atolls 
in the Maldiva Archipelago which afford some pro- 
tection to each other, are obviously explained by this 
circumstance. If the question had been, under what 
conditions the greater number of species of coral, not 
regarding their bulk and strength, were developed, I 
should answer, — probably in the situations described 
by MM. Quoy and Gaimard, where the water is 
tranquil and the heat intense. The total number of 
species of coral in the circumtropical seas must be 
very great ; in the Red Sea alone, 120 kinds, accord- 
ing to Ehrenberg, 1 have been observed. 
The same author has observed that the recoil of 
the sea from a steep shore is injurious to the growth 
of coral, although waves breaking over a bank are 
not so. Ehrenberg also states that where there is 
much sediment, placed so as to be liable to be moved 
by the waves, there is little or no coral ; and a col- 
lection of living specimens placed by him on a sandy 
shore died in the course of a few days. 2 An experi- 
ment, however, will presently be related in which 
sonu large masses of living coral increased rapidly in 
size, after having been secured by stakes on a sand- 
bank. That loose sediment should be injurious to 
1 Ehrenberg XJeber die Natur, &c. &c., p. 46. 2 Ibid p. 49. 
