MOUNTING AND PREPARATION OF OBJECTS. 59 



shakings for an hour. After standing the same 

 length of time, the fluid is removed without dis- 

 turbing the sediment at the bottom of the vessel. 

 This is repeated till the washings become colourless. 



A small quantity of the sediment is transferred 

 by a pipette to a piece of thin glass, and the fluid 

 allowed to evaporate ; the evaporation may be ac- 

 celerated by heat. 



The thin glass is next fixed in the slip and placed 

 on the stage of the microscope. A low power objec- 

 tive is adjusted and the coarser uninteresting parti- 

 cles removed in the following manner : A bristle 

 from an old shaving brush is fastened in a wooden 

 handle ; these bristles are nearly always split, and 

 when pressed on the glass, their ends separate ; the 

 object is allowed to occupy a position between them ; 

 on removal of the pressure the bristle closes and the 

 object if valuable maybe transferred to another slide, 

 or if not, discarded. 



It may be perceived that two methods are adopted, 

 either the removal of the debris from the original 

 slide, or the transference of the objects to a fresh 

 one, the former being employed when the objects 

 are in excess of the debris, the latter when the op- 

 posite is the case. 



Whichever plan is adopted, a perfectly clean cover- 

 glass being seized by a small pointed forceps, a 

 ring of stiff cement is painted round the edge and 

 the preparation mounted dry, or a drop of damar is 

 placed near the edge of the side farthest from the 

 forceps, this side is brought into contact with the 



