54 VIEWS OF THE MICROSCOPIC WORLD. 



CHAPTER II. 



FOSSIL INFUSORIA. 



" All that tread 



The globe, are but a handful, to the tribes 

 That slumber in its bosom." Bryant 



" "Where is the dust that has not been alive ?" Young. 



WHEN the loricated Infusoria die, their soft and gelatinous parts quickly 

 decompose ; but their shells or cases remain, retaining for ages their peculiar 

 forms and structures. To such an extent do these minute beings, swarming 

 throughout the waters of the globe, increase, by their various modes of produc- 

 tion ; and so rapidly do these myriad generations succeed each other, that the 

 shells of Infusoria, which perished centuries ago are now found in a fossil state, 

 constituting a large proportion of the materials of extensive tracts of land, several 

 feet in thickness, that cover the surface of the earth for many miles. These 

 cases consist, for the most part, of lime, iron, and flint, and entire ranges of hills 

 and masses of rock are composed of these minute envelopes. Dr. Ehrenberg has 

 ascertained, that no less than five kinds of rocks and mineral substances consist 

 wholly or in part, of the fossil shells of Infusoria, and that three other kinds have 

 probably the same origin. Bog iron is made up of microscopic iron shells, and 

 the remains of animalcules have been abundantly discovered in beds of marl. So 

 numerous are these fossil coverings amid the chalk cliffs, that they are detected 

 in the smallest portion of chalk that can be taken up on the point of a knife. 

 The deposites at the mouth of rivers frequently consist, to a large extent, of Infu- 

 soria, both living and fossil ; and the land is thus, in many places, continually 

 advancing upon the sea, from a cause which, until a few years ago, had entirely 

 escaped observation. 



The searching investigations 'of distinguished naturalists have furnished a most 

 interesting fund of facts, which fully attest the truth of the above remarks. In 

 Bilin, in Bohemia, a mass of slate has been discovered, forming a series of strata 

 fourteen feet thick, almost entirely composed of the flinty shells of Infusoria. It 

 is used, when ground, as a polishing powder, under the name of tripoli. A sin- 

 gle druggist's shop in Berlin disposes, yearly, of more than twenty hundred 

 weight, and the supply is still sufficient for the demands of trade. The smallest 

 quantity of this powder, when examined by the microscope, is seen to be full of 

 the fossil remains of animalcules, as is likewise true of tripoli from other locali- 

 ties. A cubic inch of the Bilin stone weighs two hundred and twenty grains, 

 and contains no less than (40,000,000,000) forty thousand millions of distinct, 

 organic forms. The species of Infusoria of which nearly the whole mass is com- 

 pacted, is the divided Gallionella, or box-chain animalcules ; a kind of Infusoria 

 which has already been described. A specimen from this slate is delineated JM 



