DEPARTMENT OF MARINE BIOLOGY.* 



Alfred G. Mayer, Director. 



Early in the year the yacht of the Department was placed at the 

 disposal of the United States Government. Permission was granted, 

 however, to retain the vessel for use at Tortugas until August, when 

 she was duly turned over to the Navy Department. We were thus 

 enabled to spend a very successful season at Tortugas, despite the 

 difficulty in maintaining research in pure science during this period 

 of international conflict. Yet, if such research has been of value in 

 the past, it must become even more necessary in the future, when we 

 come face to face with the huge task of restoring civilization to the 

 earth. 



The Director, accompanied by Professor Lewis R. Cary, of Princeton 

 University, and Mr. John Mills, our engineer, remained on the island 

 of Tutuila, American Samoa, from March 4 to April 18, 1917, engaged 

 in an intensive ecological, biological, and physiological study of the 

 coral reefs surrounding this volcanic island. 



In response to the request of the President of the Institution, the 

 Secretary of the Navy gave us a letter of introduction to Captain John 

 M. Poyer, U. S. Navy, governor of American Samoa, who together 

 with his officers did all in their power to render our visit scientifically 

 successful and socially delightful. 



Professor Cary devoted his attention to the Alcyonaria, while 

 Dr. Mayer studied the stony corals. 



It was found that rain-water falhng upon the island is acid, but when 

 it reappears in streams or springs it has become neutral or slightly 

 alkaline, due to bicarbonates or calcium, potassium, magnesium, and 

 sodium, derived not only from the salt air surrounding the island, but 

 chiefly through solution from the volcanic rocks. We see, then, that 

 the stream-water pouring outward from this purely volcanic and 

 densely forested island is not acid and can not therefore dissolve sub- 

 marine limestones by reason of its '^ acidity." Thus the Mm-ray- 

 Agassiz theory to account for the origin of atolls and barrier reefs 

 through submarine solution seems finally to be refuted, Vaughan and 

 Dole having disproven it for the Tortugas and Bahama region. 



It was proven that corals are not found off the mouths of streams 

 simply because the silt and dilution prevent their growing in such 

 places, and not because of solution of submarine hmestones. Indeed, 

 when a stream changes its course and flows out over the previously 

 formed reef-flat it deposits sandbars, but does not dissolve the coral. 



Squares were laid out over the reef-flat and all coral heads counted 

 in order to determine the distribution of the various species over the 



*Situated at Tortugas, Florida. 



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