396 BOARD OF AGRICULTURE. 



are even now exerting an important influence in changing the 

 ph3'sical features of the globe, filling up ponds and lakes, changing 

 the beds of rivers, and forming shoals or deltas at "their mouths. 

 It has been shown by the researches of Roper and other English 

 microscopists that in the mud of the Thames, if we exclude the 

 coarse sand, nearly one-fourth of the finer part of the residuum is 

 entirely composed of the silicious shells of diatoms, while Ehren- 

 berg has shown similar results from an examination of the waters 

 of the Elbe and Scheldt. In our own country the Columbia river 

 has been shown by Col, Fremont to have cut its way through a 

 deposit entirely composed of diatomaceous shells, five hundred feet 

 in thickness ! The first question which I am requested to answer 

 in regard to these deposits is whether or not they may be made of 

 economic value ? 



That they are of value has been most satisfactorily proved by 

 the researches of many authors. As early as 1850 the great abun- 

 dance of the remains of microscopic organisms, fresh and marine, 

 in the low rice-grounds of our Southern States, and the probable 

 influence of their presence in promoting the fertility of those lands, 

 was pointed out by my father. The same observer has also shown 

 that the mud of New Haven Harbor, which has been successfully 

 applied as a fertilizing agent, is largely composed of silicious exu- 

 viae, containing by analysis 58.63 per cent, of silica. To the same 

 cause is assigned by Ehrenberg the wonderful fertility of the lands 

 annually inundated by the Nile and Ganges, while an examination 

 of the tidal muds in any of our large rivers would probably lead to 

 like results. I have myself found marine diatomaceai in great 

 abundance in the St. John river, at considerable distances from its 

 mouth, while an examination of the ice when melting in the spring, 

 also showed a vast number of fresh water forms. All the cases 

 just mentioned, however, are of recent deposition ; will the sub-peat 

 deposits, which can alone be gathered in any quantity also prove 

 beneficial in their application to the soil ? I am not aware that any 

 experiments have been made to test this point, but as the deposits 

 are numerous and easily obtained, it would be well worth the 

 trouble to make the trial. It is a significant fact, and one fre- 

 quently observed, that those plants, especially the cereals, which 

 require a large amount of silicious matter to give the requisite 

 strength to their stems, and thus to promote their healthy growth, 

 have about their roots, in a living state, numbers of these very 



