FORMATION OF CORAL REEFS AND ISLANDS. PAS 
nooks and recesses deep among the corals, the rapidly moving 
waters, during the heavier swells, must produce whirling ed- 
dies of considerable force. tending to uproot or break the coral 
clumps. Moreover, it is to be kept in mind that shells and 
echinoderms make contributions as well as corals, and that all 
life grows luxuriantly in the coral seas. 
There is another process going on over the coral field, some- 
what analogous to vegetable decay, though still very different. 
Zodphytes have been described as ever dying while living. The 
dead portions have the surface much smoothed, or deprived 
of the roughening points which belong to the living coral, and 
the cells are sometimes half obliterated, or the delicate lamelle 
worn away. This may be viewed as one source of fine coral 
particles ; and as the process is constantly going on, it is not 
altogether unimportant. This material is in a fit condition to 
enter into solution, and it cannot be doubted that the water 
receives lime from this source, which is afterward yielded to 
the reef. 
In the Alcyonia family, which includes semi-fleshy corals, 
and in the Gorgonie, the lime is often scattered through the 
polyps in granules ; and the process of death sets these calca- 
reous grains free, which are constantly added to the coral sands. 
The same process has been supposed to take place in the more 
common reef corals, the Madrepores and Astreeas, and it is 
possible that this may be to some extent the case. Yet it 
would seein, from facts observed, that after the secretion has 
begun within the polyp, the secretion of lime going on takes 
place against the portions already formed and in direct union 
with them, and not as granules to be afterward cemented. 
The mud-like deposits about coral reefs (pp. 142, 183, 205) 
have been attributed to the causes just mentioned, but with- 
out due consideration. There is an unfailing and abundant 
