MOUNTING AND PKEPARATION OF OBJECTS. 59 



length of time, the fluid is removed without disturb- 

 ing 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 ob- 

 jective adjusted and the coarser uninteresting par- 

 ticles removed by a bristle from an old shaving 

 brush, 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 

 may be transferred to another slide, or if not, dis- 

 carded. 



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 

 opposite is the case. 



Whichever plan is adopted, a perfectly clean cover 

 glass being seized by a small pointed forceps, a 

 drop of damar is placed near the edge of the side 

 farthest from the forceps, this side is brought into 

 contact with the corresponding side of the slip on 

 which the objects lie, the other is allowed to sink 

 gradually to its position, in such a manner, that the 



