136 THE MICROSCOPE. 



Polygastrica, or many-stomached', and the Rotifer a, or rotating, wheel- 

 animalcules : the latter are now classed with animals of a higher 

 type of organisation. The classification of the Infusoria presents 

 considerable . difficulties, partly arising from their excessive minute- 

 ness, which renders the assistance of our best microscopes necessary 

 to enable us even to see many of them, and partly from the impossi- 

 bility of avoiding confusion from the intermixture of the genus of 

 more highly organised animals, and some plants, as the Volvodnece, 

 the Desmidiacece or Hacillariw of Ehrenberg, in various stages of de- 

 velopment. 



The term Infusoria* is applied to them because they were first dis- 

 covered in water where vegetable matter was decomposing, and there- 

 fore, the infusion was considered necessary for their production. Now, 

 however, it is an established fact, that they are in a higher state of 

 organisation when taken from pure streams and clear ponds than from 

 putrid and stagnant waters. A little bundle of hay, or sage leaves, left 

 for about ten days in a mug containing some pure rain-water, caught 

 before entering a butt, produces the common wheel-animalcules, which 

 are found adhering to the sides of the mug near to the surface of the 

 water. The only use of the vegetables seems to be to facilitate the 

 development of the latent life of the atoms of organic matter, and per- 

 haps as the first sources of their food. 



The astronomer turns his telescope from the earth, and ranges over 

 the vast vault of heaven, to detect and delineate the beautiful objects 

 of his pursuit. The naturalist turns his microscope to the earth, and in 

 a drop of water finds a wondrous world of animated beings, more nu- 

 merous than the stars of the milky way ] and these he classifies into 

 genera and families, and catalogues in his history of the invisible world. 



The Infusoria are a mighty family, as they frequently, in countless 

 myriads, cover leagues of the ocean, and give to it a beautiful tinge 

 from their vivid hue. They are discovered in all climes, have been 

 found alive sixty feet below the surface of the earth, and in the mud 

 brought up from a depth of sixteen hundred feet of the ocean. They 

 exist at the poles and .the equator, in the fluids of the animal body 

 and plants, and in the most powerful acids. A brotherhood will be 

 found in a little transparent shell, to which a drop of water is a world j 

 and within these are sometimes other communities, performing all the 

 functions granted them by their Creator, and eagerly pursuing the 

 chase of others less than themselves as their prey. 



The forms of the Infusoria are endless ; some changing their shape 

 * Infusoria (from infiisor, a pourer-in). 



