THE ANIMAL KINGDOM. 



31 



the former contains, in round numbers, forty-one millions 

 of animalcules, and as the schists of Bilin extend over a 

 surface of not less than eight to ten square leagues, and 

 are from two to fifteen feet thick, what an amount of 

 vital activity there must have been in this region to 

 produce such a mass of imperceptible skeletons ! 



Some tripolis of a red colour are employed in house- 

 painting; others serve for cleaning our plate, dish-covers, 

 &c. A few years ago people little thought that the 

 rose-colour with which we decorate our dAvellings was 

 due to the skeletons of invisible animalcules, and that it 



17. Skeletons of Silicious Infusoria, seen under the Microscope. 



was they which, from their silicious nature, enabled us 

 to give a beautiful polish to so many articles of copper. 

 It is with the osseous structures of myriads of animals 

 that we scour our cooking utensils ! 



Not only do the Infusoria enter into the composition 

 of the porous rocks, but we meet with them even in the 

 most compact that are known, such as the silex, which 

 forms our hardest pebbles and gun -flints. Mr. White, 

 in a memoir read before the Microscopical Society of 

 London, described twelve species in the flint of the chalk. 



The miraculous abundance of this once living dust in 

 the ancient epochs of our globe is fully shown in the 



