VIEWS OP THE MICROSCOPIC WORLD. 



CHAPTER II. 



MICROSCOPIC FOSSILS. 



' All that tread 



The globe, are but a handful, to the tribea 

 That slumber in its bosom." Bryant. 



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



WHEN the encased protophytes die, their soft and gelatinous parts quickly de- 

 compose; but their shells or cases remain, retaining for ages their peculiar forms and 

 structures. To such an extent do these minute plantules swarming throughout the 

 waters of the globe, increase, by their various modes of production ; and so rapidly 

 do these myriad generations succeed each other, that the shells of organisms 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 

 organisms, and that three other kinds have probably the same origin. Bog iron is 

 made up of microscopic iron shells, and the remains of the Diatomaceae 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 deposits at the mouth of rivers frequently 

 consist, to a large extent, of protophytes, 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. InBilin, 

 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 the Diatornaceae. It is used 

 when ground, as a polishing powder, under the name of tripoli. A single 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 amount of this powder, 

 when examined by the microscope, is seen to be full of the fossil remains of plan- 

 tules, as is likewise true of tripoli from other localities. A cubic inch of the Bilin- 

 stone weighs two hundred and twenty grains, and contains no less than (40.000,- 



