7 1 



MOUNTING AND LABELING. 



§ 166. Mounting Cells. — Many objects are of considerable thickness 

 and require a space or cell in which to be mounted, the wall of the cell 

 serving to support the cover-glass and to contain the mounting medium. 

 Where objects are mounted dry, that is in air, a cell must always be 

 used to support the cover-glass and to prevent the soft cement used in 

 sealing the preparation from running in by capillarity and thus flooding 

 the preparation. 



Fig. ^8a. Turn-Table for Sealing Cover-Glasses and Making 

 Shallow Mounting Cells. {Queen & Co.) 



§167. Preparationof Mounting Cells. — (A) Thin Cells. These are 

 most conveniently made of some of the microscopical cements. Shellac 

 is one of the best and most generally applicable (§ 193). To prepare a 

 shellac cell, place the slide on a turn-table (Fig. 38 s1 ) and center it, that 

 is get the center of the slide over the center of the turn-table. Select a 

 guide ring on the turn-table which is a little smaller than the cover- 

 glass to be used, take the brush from the shellac, being sure there is 

 not enough cement adhering to it to drop. Whirl the turn-table and 

 hold the brush lightly on the slide just over the guide ring selected. 

 An even ring of the cement should result. If it is uneven, the cement 

 is too thick or too thin or too much was on the brush. After a ring is 

 thus prepared remove the slide and allow the cement to dry spontan- 

 eously or heat the slide in some way. Before the slide is used for 

 mounting, the cement should be so dry when it is cold that it does not 

 dent with the finger nail applied to it. 



A cell of considerable depth may be made with the shellac by adding 

 successive layers as the previous one drys. 



(B) Deep cells are sometimes made by building up cement cells, but 

 more frequently, paper, wax, glass, hard rubber or some metal is used 

 for the main part of the cell; Paper rings, block tin or lead rings are 

 easily cut out with gun punches. These rings are fastened to the 

 slide by using some cement like the shellac. 



§ 168. Sealing the Cover-Glass. — (A) For dry objects mounted in 

 cells. When an object is mounted in a cell, the slide is warmed until 

 the cement is slightly sticky, or a very thin coat of fresh cement is put 



