434 THE MICROSCOPE. 



breadth, abounds in Infusoria and other siliceous remains. 

 Ehrenberg, on examining the immense deposit of mud 

 at the harbour of Wismar, Mecklenburg-Schwerin, found 

 one-tenth to consist of the shells of Infusoria ; giving a 

 mass of animal remains amounting to 22,885 cubic feet 

 in bulk, and weighing forty tons, as the quantity annually 

 deposited there. How vast, how utterly incomprehen- 

 sible, then, must be the number of once living beings, 

 whose remains have in the lapse of time accumulated ! 

 In the frigid regions of the North Pole no less than sixty- 

 eight species of the fossil Infusoria have been found. 

 The guano of the island of Ichaboe abounds with fossil 

 Infusoria, which must have first entered the stomachs of 

 fish, then those of the sea-fowl, and became ultimately 

 deposited on the islands, incrustating its surface ; whence 

 they are transported, after the lapse of centuries, to aid 

 the fruition of the earth, for the benefit of the present race 

 of civilized man. The hazy and injurious atmosphere met 

 with off Cape Verd Islands, and hundreds of miles distant 

 from the coast of Africa, is caused entirely by a brown 

 dust, which upon being examined microscopically by 

 Ehrenberg, was found chiefly to consist of the flinty sheila 

 of Infusoria, and the siliceous tissue of plants : of these 

 Infusoria, sixty-four proved to belong to fresh-watei 

 species, and two were denizens of the ocean. From the 

 direction of the periodical winds, this dust is reasonably 

 supposed to be the finer portions of the sands of the desert 

 of the interior of Africa. 



The deposit of the beneficent Nile, that fertilises so 

 large a tract of country, has undergone the keen scientific 

 scrutiny of Ehrenberg ; and he found the nutritive prin- 

 ciple to consist of fossil Infusoria. So profusely were they 

 diffused, that he could not detect the smallest particle of 

 the deposit that did not contain the remains of one or 

 more of the extensive but diminutive family that once 

 revelled in all the enjoyment of animal existence. It is 

 very remarkable that at Holderness, in digging out a sub- 

 merged forest on the coast, numbers of fresh-water fossil 

 DiatomacecB have been discovered, although the sea flows 

 over the place at every tide. 



Mode of Preparing Fossil Infusoria. Before entering 



