250 UTILIZATION OF MINUTE LIFE. 



thickness. There are seven or eight similar deposits 

 in Mexico. All these deposits contain a certain 

 amount of vegetable remains. Indeed, a similar 

 kind of earth, composed almost entirely of micro- 

 scopic plants (?) (Diatomacece) , underlies the town 

 of Richmond, in Virginia, North America; and 

 the layer upon which this town is built has a 

 thickness of no less than twenty feet. 



The guano deposits of Ichaboe, and indeed all 

 other beds of this substance, abound in remains of 

 animalculae and inferior algae. 



In some mud brought from the Levant, in 1844, 

 hundreds of siliceous shells of Infusoria, Diatomaceas, 

 etc., were discovered; and some earth recently 

 found near Newcastle, in England, was found to 

 be almost entirely composed of fossil Infusoria and 

 Sacillaria (minute organisms that some naturalists 

 consider as plants, others as animals) . 



Moreover, some specimens of siliceous rock, from 

 the Isle of France, were found by Ehrenberg to 

 consist principally of fossil Infusoria, identical with 

 certain living species. 



In some of the plains of Eastern Germany such 

 infusorial deposits are both common and exten- 

 sive. The town of Berlin is built upon one of 

 them, which measures about twenty-five yards 

 in thickness. But it is a curious fact that the 

 deposit which underlies the town of Berlin is 



