308 Doubts Relative to the Epochal and 



families of the foraminifera and polypifera have not been the 

 efficient factors of our lime strata ? The bare fact that much 

 of our lime, especially in the oolite and cretaceous systems, 

 is nothing else than organic exuviae, is too patent to admit 

 of a moment's doubt as to its correctness ; but the difficulty 

 does not rest with the admission of such facts, since the 

 original doubt still presents itself Whence do these polypi 

 obtain their lime ? The answer to this question usually is, 

 that however small the quantity of lime sea water contains 

 in a given measure, yet such is the industry of the madre- 

 pores, astrseas, the millepores and seriatopores, that islands 

 are raised by them in the midst of the ocean, and a continent 

 is being girt by their increasing labours. Granted that it is 

 so, yet the BED of the ocean in many parts, and the washing 

 of its endless SHORES, yield a constant fresh supply of lime 

 to those waters from which the lime has been abstracted 

 by the industrious zoophytes. The founding and extending 

 of coral-reef building has nothing to do with the small 

 amount of carbonate of lime held in solution in sea water at 

 any one given time, but whether, when that is exhausted by 

 the reef-building polypi, there is placed within the limits of 

 the ocean's expanse lime sufficient to replace that abstracted 

 from the waters, and so the unceasing demands of the polypi 

 receive an unceasing supply. 



For if there is not sufficient lime, then, where that limit 

 defines itself, there their work must cease since zoophytes 

 are no more alchymists than the higher order Bimania and 

 the power to convert silicon or alumina into lime, where the 

 latter element (or compound) ceases to exist, would be 

 necessary to enable them to carry on their work ; for they 

 cannot create matter or lime, they can but apply it when 

 present. Therefore, the organic source of lime is bounded 

 by the same limit as that of pure sedimentary rock namely, 

 the quantity deposited as exuvice is limited by the sources or means 



