AND THE MICROSCOPE. 35 



systems of rocks are found almost solely consisting of them. 

 The siliceous shells sometimes become blended together by 

 a peculiar process, not yet explained, and so form flints and 

 opals. The Botanist must not disdain a nearer acquaintance 

 with these siliceous animalcules, for the question which has 

 long been agitated, even with some bitterness, whether 

 these little organisms are animals or plants, is not yet set at 

 rest. In regard to magnitude, the formations originating 

 from the calcareous Infusoria are still more important. A 

 considerable portion of Russia, on the Wolga, of Poland, 

 Pomerania (e. g. Rugen), Mecklenburg, Denmark, Sweden, 

 of the south of England, Northern Ireland, the north of 

 France, Greece, Sicily, of the north of Africa, and perhaps 

 also Sahara, of the north-western and Arabian portion of 

 Asia, consist of such calcareous soils and masses of chalk 

 rock, the thickness of which may often be estimated, as in 

 England, at a thousand feet. The imagination halts in the 

 attempt to realize these masses of organic life, when we 

 remember that a single chalk-enamelled visiting card forms 

 a zoological cabinet of, perhaps, a hundred thousand shells. 



As Galileo, Kepler, Newton and Herschel introduced us 

 into an infinite world of huge magnitudes, as Columbus, 

 Magellan and their successors first unfolded to us one 

 entire half of the earth, so in the present day, has Ehren- 

 berg, by his untiring industry, laid open to us a wonderful 

 world of organic life, which, small as are the individuals 

 composing it, invisible to the keenest eye when unassisted, 

 through the inconceivable activity of development, through 

 the number, vast beyond expression, of single beings, heaps 

 up masses, before which man himself seems insignificant. 



On the 26th of January, 1843, a great crowd collected 

 at the Round Down Cliff, near Dover, in anxious expecta- 

 tion, to witness the event of the grandest and most daring 



3* 



