142 SHIELDS OF ANIMALCULES. 



fifty-two years. The mass may have been raised 

 by a storm from a Courland marsh, and merely car- 

 ried away, but may also have come from a far distant 

 district. The original locality of the substance 

 appears to be neither the atmosphere, nor America ; 

 but most probably either East Eussia or Courland, 



In Sweden, on the shores of the lake Lettnaggsjon, 

 near Urnea, a vast quantity of extremely fine matter 

 is found, much resembling flour in appearance, and 

 called by the natives, Mountain Meal.* It is used 

 as food, being mixed up with flour, and is nutritive. 

 This substance is ascertained, by examination with 

 a microscope, to consist of nothing else than the 

 shelly coverings of certain polygastric animalcules, 

 which coverings, as the animals perish, accumulate 

 from age to age at the bottom of the waters, and 

 form a deep stratum ; this drying on the shore, or 

 in places no longer covered by the water as formerly, 

 assumes the appearance whence it has its name, and 

 each particle is the relic of a microscopic animal. 



The marvellously rapid increase of these creatures 

 gives rise to other extraordinary results. As from 

 one individual, in four days, one hundred and forty 

 millions of millions would have existed, so there 

 is a sufficiency to form two solid cubic feet of sili- 

 ceous rock. Most of the solid skeletons of polygas- 

 tric animalcules are external siliceous covers, which 

 envelop the entire body ; they long resist decay, and 

 exhibit the general form and character of the species 

 * Borgmehl. 



