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On the Remains of Infusorial Animalcules in Volcanic Rocks. By 

 C. G. Ehrenberg. 



The influence of animalcules (or organic bodies so minute as to be 

 invisible to the naked eye) on the formation of the actual solid 

 masses which make up the earth's crust has only lately been recog- 

 nised, even with regard to the newest stratified rocks and those of 

 the most recent geological period ; but amongst these the so-called 

 mountain meal, peat, sea and river-mud, bog-iron, the earth in which 

 the mineral Vivianite occurs, and others, are now known to be either 

 partly or entirely composed of the organic products secreted by these 

 little animals. 



A similar origin must however now be assigned to those tertiary 

 rocks which are known by the names tripoli, polishing slate and 

 semi-opal, to some of the porcelain earths, to the so-called dysodil, 

 and to the paper-coal of the brown coal formation ; and even among 

 the upper secondary rocks we find that the greater part of the white 

 chalk, the nummulite and catacomb limestone of Egypt, the firestone 

 of the same period, and several of the chalk marls, are, beyond ques- 

 tion, the direct products of similar minute organic beings. 



Amongst the middle secondary rocks again, we find that the 

 hornstone of the coral rag of Cracow, and some widely-spread oolitic 

 rocks in various parts of Europe exhibit distinct traces of a similar 

 origin ; while even in the newer palaeozoic rocks we learn from 

 Count Keyserling and Prof. Blasius that there is a compact lime- 

 stone of the carboniferous period near Lake Onega in which these 

 little organic bodies are present in vast abundance, associated with a 

 species of Bellerophon. 



The hornstone of Tula also, considered and described by Helmer- 

 sen as mountain limestone, and in which Choristites mosquensis 

 is present in great beauty, has certainly been formed for the most 

 part by these microscopic animalcules ; and it is not long since Prof. 

 Bailey of New York forwarded to Europe specimens of a hornstone 

 from near Madison, Wisconsin U. S., considered by the American 

 geologists as belonging either to the carboniferous or oolitic group ; 

 and this M. Ehrenberg on examination has found to be also entirely 



