MICROSCOPE AT THE POND-SIDE. 67 



interior of the little fleshy lump of which the ani- 

 mal is composed. They are found in the vorticella, 

 and in most of the true animalcules. 



All animalcules have been called infusory, be- 

 cause they seem so abundant in many kinds of 

 vegetable infusions. Ehrenberg divided them into 

 Polygastric and Rotiferous. The last are also called 

 wheel-animalcules, as, when looked at through the 

 Microscope, they appear to be supplied with little 

 wheels on the upper part of their body. The most 

 common form of these creatures is the Rotifer 

 vulgaris, represented at figure 41, plate 2. The 

 branches or leaves of any of our common water- 

 plants can scarcely be examined without some of 

 those pretty little creatures being found nestling 

 among them. The structure of these creatures is 

 highly complicated, and the family to which it 

 belongs is far removed from the polygastric ani- 

 malcules with which it is associated by Ehrenberg. 

 On examination, the wheels will be found to 

 consist of two extended lobes, the edges of which 

 are covered with cilia. These cilia are in a con- 

 stant state of movement, and produce the appear- 

 ance of wheels moving on an axis. Between the 

 wheels is the entrance to the mouth, which, in 

 many species of wheel-animalcules, is furnished with 

 a strong pair of jaws. This leads to an oesophagus, 

 a stomach, and an intestinal tube. Two little spots 

 on the neck seem to indicate the existence of eyes ; 

 whilst a projecting organ, believed to be analogous 

 to the antennae, or feelers of insects, is seen 

 directly below them. The tail is finished off with 

 a pair of little nippers, by which the creature has 

 the power of attaching itself to objects. When 

 moving, its whole body is extended, but it has the 

 power of drawing itself up like a telescope in its 

 case, and appearing almost round. 

 F 2 



