OF THE MICKOSCOPE. 179 



ble quantity of it through a filter, the surface of which will 

 then furnish a large amount of valuable matter. 



But it is not in such fields that the microscopist will find his 

 best hunting grounds. Along the edges of quiet pools of clear 

 water is the best place for the finer vegetable forms, such as 

 the Volvox Globator, Closterium, etc. If the water is much con- 

 taminated with dead animal matter or with sewage, nothing will 

 be found but the coarser organisms and animalcules, such as 

 Paramecium. The same is true of small pools found in woods, 

 or very much shaded with trees, and filled with dead leaves. 

 Such places are, however, the favorite haunts of the larvse of 

 insects, and also of frogs and Tritons. The size of the pools is 

 not of much consequence. We remember on one occasion to 

 have found by the roadside in Centre County, Pennsylvania, a 

 little pool which was almost filled with the larvre of Tritons. 

 The gills, which were beautifully developed, would have formed 

 a splendid object under the microscope, but when we returned 

 next day, for the purpose of securing some, the water had dried 

 up, and the larvae were all gone. 



The little pools formed in boggy ground by the footsteps of 

 cattle will often be found to contain large quantities of one or 

 two species of desmids or diatoms. It will not do to look for 

 these objects in similar pools formed in ordinary soft land, and 

 temporarily filled with rain water. The ground must be na- 

 turally and constantly wet, so that the pools are always kept 

 filled by the infiltration of water from the surrounding soil. 

 Such pools, however small, usually contain a large number of 

 specimens, and it is in such places that one is most likely to 

 find a supply of one variety unmixed with any others. 



While many of the most interesting objects will bo found 

 swimming freely about in the water, others of great beauty are 

 always attached to floating weeds, sticks, etc. We have gen- 

 erally been most successful in discovering specimens of this 

 kind when we have placed the gathering in a large glass jar, and 

 allowed it to stand quiet for some time. The water will then 

 settle, and the objects of which the microscopist is in search 

 will have time to expand, when they may be seen in a form 

 resembling light mould, or down, attached to the surfaces of 

 the solid matters. 



