NATURAL HISTORY OF THE DIATOMACE^. 461 



skeletons of marine species. The city of Richmond, Va., rests upon 

 such a stratum, which varies in thickness from twelve to twenty-five feet, 

 and which extends to Fortress Monroe and over the Potomac river into 

 Maryland, and all the way down on both sides of the Patuxent river in 

 that state. The principal localities from which these deposits, fresh- 

 water and salt-, have been obtained so far, will be mentioned in the 

 directions for collecting, to be given hereafter. 



Besides objects of great beauty and scientific interest, the uses to 

 which the diatomaceae have been put may be briefly summarized. It 

 is to be hoped that the unlearned, whose attention has for the first time, 

 perhaps, been called to them by this sketch, will feel that the elegance 

 of their forms and the geometrical purity of their sculpture will recom- 

 mend them sufficiently, without eliciting the question, which unfortu- 

 nately has been propounded with reference to other scientific subjects, 

 viz., What good are they? That they serve as food for numerous 

 aquatic animals is plainly shown by the fact of their being found in 

 their stomachs; but, if that were their only use, it could hardly be 

 said that they were of value to man directly. Who would suppose 

 that these little atomies, so seemingly insignificant, could serve as sus- 

 tenance for the human race? and yet such is the fact. In the bleak 

 and almost barren parts of Lapland, during times of scarcity from failure 

 of the crops, the infusorial deposits are turned to account, under the 

 name of "berg-rnehl" or mountain meal, to eke out the scanty supply of 

 flour with which they are mixed before it is made up into bread and 

 eaten. In some other parts of the world we find wild nations making a 

 similar use of such "infusorial deposits;" but we can hardly say they 

 serve as food, for although some authors have supposed that some of the 

 organic matter they contain may be absorbed by the stomach or intes- 

 tines, it is not likely that such is the case. It is much more probable 

 that the earthy material serves to clog the stomach, and, by the mere act 

 of distention, arrest for a time the pangs of hunger. Their siliceous 

 character is opposed to their serving as food in the true acceptation of 

 that word. In Samarancy and Java, under the name of "tanah," an 

 earth of this kind, made up of the siliceous remains of diatomaceas, is 

 eaten. It is described as "generally solid, plastic, and sticky, and is 

 rolled and dried in the shape of small sticks over a charcoal fire, and is 



