10 MR GOODCHILD ON 
granules accumulate and gradually become more compact, 
being moulded, as they do so, after the form of those parts of 
the body from whose tissues they are deposited. Little by 
little the growth of the calcareous particles excludes more 
and more of the animal matter, so that the coral animal 
itself grows, or is, as it were, gradually thrust, to an in- 
creasingly-greater distance from its original point of attach- 
ment. Eventually, it finds itself at the end of a small 
column of carbonate of lime, whose form, both externally 
and internally, has been determined entirely by the shape 
of those parts of the animal from and within which it was 
deposited.* 
There are some modifications of the mode of deposition 
which are characteristic of different groups of corals; but, 
in general terms, the process of coral growth goes on in very 
much the way just described. 
The early stages of the life-history of these animals 
present several points of interest and importance in the 
present connection. The adult animals are fixed to some 
solid object below the surface; but the fry, in the earlier 
stages of their existence, are minute, free-swimming animals, 
which live in great swarms at or near the surface of the 
ocean. In this state they are drifted far and wide by the 
surface currents, and in so doing are exposed to so many 
dangers that myriads of the fry must perish for every one 
that survives to reach the adult condition. They become 
the prey of innumerable fellow-creatures; they quickly 
perish with a fall of the surface temperature of the ocean 
water, such as must happen when they are drifted from a 
warmer current into a colder, as when they are transported 
by the Gulf Stream northward from the West Indies. If 
the current that transports them happens to meet an out- 
flowing current off the mouth of a river, the influx of fresh- 
water kills them off; and even if the water be more or less 
salt, the presence of the mud in suspension is inimical to 
their well-being. So they die by the million, and only a 
few out of the many survive. Those which do escape 
* One of the very best simply-worded descriptions of coral animals and 
corals is given by the late Professor Martin Duncan in his edition of Cassell’s 
Natural History, pp. 292-311. 
