GROWTH OF THE CORAL COLONY 93 



branching, one other feature distinguishes the comparatively- 

 deep-water forms from those that inhabit the surface waters — 

 and this is the general absence of pigment throughout every 

 portion of the colony. Deep-water forms are therefore as 

 a rule pale or entirely colourless. 



It will be seen from these instances that the form of the 



Fig. 27. 



KOUGH-WATER Type OF HiGHLY BRANCHED Maclrepora. 



From an actual specimen of Maclrepora pulchra taken 

 from the barrier. 



colony varies as the outcome of the influences of the environ- 

 ment ; and every embryo which settles in any habitat has to 

 comply with the demands of the physical conditions, and 

 modify its inherited growth tendency — or perish. Totally 

 different forms are produced in totally different environments, 

 but these forms must not be regarded as " species," for they 

 are mere variations of vegetative growths in response to the 

 necessities of the life-surroundings of the colony. 



