58 PROCEEDINGS OF THE PHILADELPHIA MEETING 



TITLES AND ABSTRACTS OF PAPERS PRESENTED IN GENERAL SESSION AND 



DISCUSSIONS THEREON 



RELATION OP BACTERIA TO DEPOSITION OF CALCIUM CARBONATE 



BY KARL F. KELLEKMAN ^ 



(Ahstract) 



At the suggestion of Dr. T. Wayland Vaughan, bacterial studies of water 

 and bottom mud from the Great Salt Lake and sea-water and bottom deposits 

 from the vicinity of Florida and the Bahamas were undertaken in the hope 

 of supplementing the work of Vaughan,= of Drew,^ and of Dole* in regard to 

 the probable agencies concerned in the precipitation of calcium carbonate and 

 the formation of oolites. 



It has been possible to form calcium carbonate by the action of bacteria on 

 various soluble salts of calcium, both in natural waters and in synthetic 

 mixtures. The most important natural precipitation is probably the trans- 

 formation of calcium carbonate by the combined action of ammonia, produced 

 by bacteria either by the denitrification of nitrates or by the fermentation of 

 protein, together with carbon dioxide, produced either by the respiration of 

 large organisms or the fermentation of carbohydrates by bacteria. Both ordi- 

 nary crystals of calcium carbonate and oolites may be produced by the growth 

 of mixed cultures of bacteria, either in salt or fresh water. The zonal struc- 

 ture of the oolites of bacterial origin and of those found in nature in oolitic 

 deposits appears to be exactly the same ; undoubtedly this shows the similarity 

 of the processes of their origin. 



Eead in full from manuscript. 



CORAL REEFS AND REEF CORALS OF THE SOUTHEASTERN UNITED STATES, 

 THEIR GEOLOGIC HISTORY AND SIGNIFICANCE 



BY THOMAS WAYLAND VAUGHAN 



(Abstract) 



After briefly alluding to some of the more recent publications on coral reefs, 

 the author stated what in his opinion were the necessary lines of investigation 

 in order to understand the ecologic factors influencing coral-reef development, 

 the constructional role of corals and other agents, and the series of geologic 

 events which preceded any particular coral-reef development. The geologic 

 history of the extensive coral reefs of the southeastern United States and 

 near-by West Indian islands, which have been the subject of investigation for 

 a number of years, was outlined, and the bearing they have on the theory of 

 coral-reef formation was indicated. 



The author stated his conclusions regarding the Florida coral reefs as fol- 



1 Introduced by T. Wayland Vaughan. 



2 T. W. Vaughan : Bull. Geol. Soc. Am., vol. 25, No. 1, p. 59. March, 1914. Also 

 Publication No. 182, Carnegie Inst, of Washington, pp. 49-67. 



=* G. H. Drew : Publication No. 182, Carnegie Inst, of Washington, pp. 1-45. 

 * R. B. Dole : Publication No. 182, Carnegie Inst, of Washington, pp. 69-78. 



