76 CORAL AND ATOLLS 



consequence the surface-pattern and the density of the coral 

 may vary widely within the limits of a species. The same 

 variation is to be seen in the level of the site of orisrin of the 

 lateral buds : this will have to be referred to later on when 

 the cause of the variations is considered. 



Another feature that is subject to an excess of variation, 



Fig. 14. 



Example oy an Amorphous Type oe Growth. 



{Porites.) 



and must therefore be considered, is the amount of raising 

 from the general surface of each individual corallite. Every 

 corallite of the colony may be flush with the general surface, 

 or it may be raised from it in varying degrees, and the degree 

 of raising gives very characteristic appearances to the colonies. 

 The degree of elevation of the corallite is no safe criterion for 

 determining specific rank, for it is a variable factor depending 

 altogether on the reactions of the coral to its environment. 

 The portions of the coral body which lie between the actual 

 corallites are also important in this connection, for many 



