274 LOUIS AGASSIZ. 



upon the measured and cautious tread, intro- 

 duced by Saussure in geology. You, too, will 

 reconsider all this, and will yet treat the views 

 of Saussure and Escher with more respect. 

 Everything here turns to infusoria. Ehren- 

 berg has just discovered that an apparently 

 sandy deposit, twenty feet in thickness, under 

 the " Luneburgerheyde," is composed entirely 

 of infusoria of a kind still living in the neigh- 

 borhood of Berlin. This layer rests upon a 

 brown deposit known to be ten feet in thick- 

 ness. The latter consists, for one fifth of the 

 depth, of pine pollen, which burns. The rest 

 is of infusoria. Thus these animals, which 

 the naked eye has not power to discern, have 

 themselves the power to build up mountain 

 chains. . . . 



