ANTIQUITY OF THE BACTERIA 17 



long ago as 1879, Van Tieghem called attention to the evidence 

 of bacterial existence, if not the actual presence of bacteria, in 

 the silicified vegetable remains from the coal measures of St. 

 fitienne. Since then, in a series of admirable memoirs, Renault 1 

 has confirmed and extended those observations. That marine 

 Algae play an important part in certain geological horizons, 

 notably in connexion with oolitic and dolomite structures, was 

 laid down by Professor Garwood 2 in 1913. 



But even before this date a brilliant investigator, Drew, 

 who died all too young, had in 1911 studied the calcareous 

 muds now being deposited in the lagoons on the coast of Florida, 

 and had shown that in the warm tropical waters of the Gulf 

 the commonest living form is a denitrifying bacillus which, by 

 the removal of the nitrogen from the water, leads to a combina- 

 tion between calcium and dissolved carbon dioxide, with, as 

 result, the precipitation of the insoluble calcium carbonate. 

 He isolated and cultivated this form and obtained in vitro the 

 deposit of calcium carbonate from the sea water. In the follow- 

 ing year he found the same Bacterium calcis extraordinarily 

 abundant in the chalky mud of the Great Bahama reef, as many 

 as 160 million bacilli being present in 1 c.cm. of the surface ooze. 3 



These observations indicate, therefore, that bacteria, even 

 to a greater extent than the larger marine Algae, have been 

 responsible for the deposit of the vast beds of chalk and lime- 

 stone in which no coralline or other fossils are to be detected. 

 And now, in the oldest of all stratified rocks, in the pre-Cambrian 

 or Algonkian deposits of America, Dr. Walcott, the head of the 

 Smithsonian Institute, has discovered fossilized chains and 

 clusters of cells which from their appearance and his description 

 belong to the Cyanophyceae, the blue-green Algae closely related 

 to the bacteria, and with these other clusters of coccus-like 

 cells which may, or may not, be bacteria. 4 



He likewise concludes that "it is quite probable that the 

 bacteria were the most important factor in the deposition of 



1 Renault, B., " Sur quelques micro-organismes des combustibles fossiles," 

 Bull, de la Societe de I'Industrie minerale, St-Stienne, vols. vii. and xiv., 1899, 

 1900 (with folio atlas of 20 plates of untouched photographs). 



2 Geological Magazine, x., 1913, pp. 440, 490, and 545. 



3 Papers from Tortugas Laboratory, Carnegie Institute of Washington, v., 

 1914, 44. 



* If bacteria then they are much larger than the micrococci of to-day. 



O 



