[ 479 ] 



On the Precipitation of Calcium Carbonate in the Sea 

 by Marine Bacteria, and on the Action of Denitri- 

 fying Bacteria in Tropical and Temperate Seas. 



By 

 G. Harold Drew. 



With Two Figures in the Text. 



TABLE OF CONTENTS. 

 Introduction ....... 



General Considerations and Previous Work .... 



Description of Apparatus ..... 



Culture Media and Methods ..... 



The Investigation of Samples of Sea-water taken oft' Port Royal, Jamaica 

 The Investigation of Samples of Sea-water taken around the Dry Tortugas 

 The Investigation of Samples taken from a point 70 miles west of Ushant Island 



France ... . . 



The Investigation of Samples from the Marquesas Keys, Florida, and the Experi 



mental Precipitation of Calcium Carbonate by Bacterial Agency 

 Some Considerations on the Physiography of the Tongue of the Ocean and 



Andros Island, Bahamas, B.W.I. .... 



Bacterial Investigations in the Deep Water in the Tongue of the Ocean . 

 Hydrographic Observations in the Tongue of the Ocean 

 Bacterial Investigation of the Chalky Mud-flats which are being deposited to th 



West of Andros Island, Bahamas .... 



Conclusion ....... 



PAGE 



479 



480 

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 497 



501 



503 



506 

 510 

 515 



519 

 522 



INTEODUCTION. 



The investigations in the American Tropics described in this paper 

 were made during the summers of 1911 and 1912 under the auspices 

 of the Carnegie Institution of Washington : the work was made possi- 

 ble by the invaluable help and kindness of Dr. Alfred G. Mayer, 

 Director of the Department of Marine Biology. The investigations in 

 Temperate waters were made from the Plymouth Laboratory of the 

 Marine Biological Association of the United Kingdom, and my thanks 

 are due to the Council and Director of the Association for giving me 

 every facility for the work. 



Originally the primary object of the investigations was to make a 

 study of the action of marine denitrifying bacteria in Tropical and 

 Temperate seas. The discovery during the course of the experiments 

 that these denitrifying bacteria also possess the power of precipitating 

 Calcium carbonate from soluble Calcium salts present in sea-water 

 has, perhaps, by its geological significance, somewhat overshadowed 

 the interest of the primary object of the work. 



NEW SERIES. — VOL. IX. NO. 4. MAl'.CH, 1913. 2 I 



