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REPORTS ON INVESTIGATIONS AND PROJECTS. 



Table of dimensions of naturally attached yearling corals. 



* Perhaps 2 years old. 



incrusting organisms, growth-rate is one of the most important factors in 

 determining which shall survive. Corals may grow with great rapidity in 

 locations where they can not survive, or are only poorly represented, because 

 the habitat is suited to other organisms of a more rapid rate of growth. In 

 the vicinity of the Tortugas there are many obstacles in the way of free 

 planulae obtaining a footing and developing into colonies. They settle and 

 begin their initial development best precisely in those places where they are 

 most likely to be smothered by other organisms. The relatively small num- 

 ber of planulae that attach in crevices or small protected spots, in which sea- 

 weeds, sponges, etc., do not get a footing, and when the environment is 

 unfavorable for the growth of these, are those that have the best opportunity 

 for growth and ultimate survival. To offer a proper foundation for a coral 

 reef, the sea-bottom must, besides being hard, clean, with a free circulation 

 of water over it, also be rough. Irregularities in the surface constitute an 

 essential factor. 



