106 NATURAL HISTORY 



which it is easily procured, and managed with great 

 facility. 



Collect, in a large wide-mouthed phial, some of the 

 matter from the surface of such stagnant ponds as are 

 covered with a dull-green substance, which, at a distance, 

 may be mistaken for confervse, or duck-weed, but which 

 is easily distinguished from it, on a closer examination, 

 by the masses not being connected by fibres or threads, 

 but loose, like dust. This matter, with some of the 

 water of the pond, must be carefully carried, for the 

 least agitation will cause it to sink to the bottom, and 

 kill many of the animalcules, while the rest will be some 

 days before they re-ascend. If a portion of it is placed 

 on the stage-glass under the microscope, it will be found 

 to consist of an immense number of beautiful green 

 animalcules of different shades of colour, from a bright 

 yellow-green to a deep blue- green. If your microscope 

 has sufficient penetrating power, and is free from aber- 

 ration, you will perceive in the pellucid part of the head 

 a bright orange-brown spot, as shewn in the drawing, 

 figures 105 to 109 : this spot, which is the eye of the 

 creature, is situated on one side, just under the surface 

 of the envelope. The most usual, or what perhaps may 

 be called the normal form of this creature, is shewn at 

 figure 107, where is also exhibited by the arrows the 

 direction of the currents produced by the cilia at the 

 mouth. The general aspect of the body is very ac- 

 curately shewn in this figure, several parts of which 

 are covered with opaque green spots; the centre is often 



