MICROSCOPE IN FRESH WATER. 39 



CHAPTER IV. 



A HALF-HOUR WITH THE MICROSCOPE 

 IN FRESH WATER. 



CISTERNS, ditches, ponds, and rivers, contain nume- 

 rous objects to interest the microscopic observer. 

 Some of these objects float on the surface of the 

 water j others are found swimming about in the 

 middle of the water ; whilst the greater number, 

 perhaps, are found at the bottom of the water. In 

 collecting objects from fresh water, little bottles 

 may be used, and a common spoon or small net 

 employed for collecting them. Where the objects 

 are only few, large quantities of. the water should 

 be allowed to stand, and the whole poured off, 

 with the exception of a table-spoonful or two, 

 which may be then placed in a wine-glass. A little 

 of the sediment may be taken up in a pippet or 

 glass tube, and conveyed to the animalcule-cage, 

 and the cover having been put on, it may be 

 placed under the Microscope. If the objects are 

 moving about too rapidly, the cover may be pressed 

 down till they are secured. They may be first 

 sought out with a low power, and when it is 

 wished to examine them more closely, a higher 

 power may be put on. 



Of all the forms of microscopic plants which are 

 found in fresh water, those belonging to the families 

 of desmids and diatoms are most interesting. We 

 have already spoken of plants consisting of one 

 cell, and these also consist of one cell ; but they 

 have this peculiarity, that their cells are divided 

 into two equal parts, each part having the same 



