GROWTH OF THE CORAL COLONY 91 



as every grade of environment is to be found, every grade of 

 modification of the colony is represented. 



Corals grow in great luxuriance on the wave-stirred outer 

 slopes of the atoll, but this is a site by no means to be con- 



Fjg. 26. 



A Colony or Pocillopora 



Whose growth is branched in complex fashion. This form is 



linked to the less highly branched forms by the reduction of 



its smaller branchlets. 



founded with the surf-line of the barrier. They grow also in 

 the numerous pools of the barrier flats, in the inlets to the 

 lagoon, and in the lagoon itself; and each environment has 

 its own peculiar conditions. 



In the barrier pools every modification of life-surroundings 

 is to be met with, for these pools are of varied depth, they 

 are filled with sand, or are of bare rock ; and they have a 

 varying exposure to the wave action of the barrier breakers. 



