460 SUPPLEMENTARY NOTES. 



described by Berzelius, 1833, and found by him to contain Silex, 

 animal matter, and crenic acid, is eaten in Lapland in seasons of 

 scarcity, mixed with ground corn and bark, in the form of bread; 

 in 1833 this occurred in the Commune of Degerfors. M. Retzius 

 has discovered in this Bergmehl, nineteen species of Infusoria 

 with siliceous shields. This deposits appears to be analogous to 

 tlie Kieselguhr of Franzenbad. 



L'Institut, 22 Feb. 1837. No. 198. 



Ehrenberg has farther ascertained that a soft yellow ochreous 

 substance called Raseneisen, (Marsh Ochre, or Meadow Earth,) 

 which is found in large quantities every spring in Marshes about 

 Berlin, covering the bottom of ditches, and in the footsteps of 

 animals, is composed in part of Iron secreted by Infusorial animal- 

 cules of the Genus Gaillonella. This Iron may be separated from 

 the siliceous shields of these animals, which retain their form after 

 the extraction of the Iron. He has also detected similar ferruginous 

 and siliceous remains of Infusoria in similar ochreous substances, 

 from the Ural, and New York, and also in a yellow earthy sub- 

 stance formed on the surface of the mineral water of the saltworks 

 at Colberg and Dlirrenberg. This substance is used for iron colour 

 in house painting at Colberg. The iron secreted by these animal- 

 cules, and connected with their siliceous shields, forms after death 

 a nucleus to which other iron is attracted, from a solution of this 

 metal in the water which these animals inhabit. 



In another communication, Prof. Ehrenberg announces that 

 certain indurated and heavy portions of the Polierschiefer of Bilin, 

 called Saugschiefer, are also the remains of Gaillonellse, cemented 

 and tilled with amorphous siliceous matter derived from these infu- 

 soria; and that nodules of Semiopal, which occur in the same 

 Polierschiefer, are also composed of Silex derived from infusorial 

 remains that have been dissolved and formed into siliceous concre- 

 tions, having dispersed through them numbers of infusorial shields, 

 partially dissolved, together with others that are unaltered. Ehren- 

 berg also thinks he has found indications of microscopic orgr.nic 

 bodies of a spherical form, (some, perhaps, allied to the existing 

 genus Pyxidicula,) in semi-opal from Champigny, and also in 

 semi-opal from the Dolerite of Steinheim near Hanau, and from 

 the Serpentine of Koseraitz in Silesia, and in precious opal from 



