1 68 MOUNTING AND LABELING \_CH. VII 



on the cell and pressed down all around till a shining ring indicates its adherence 



(2 249)- 



5. The cover-glass is sealed (\ 249). 



6. The slide is labeled (| 308). 



7. The preparation is cataloged and safely stored (\ 309, 311). 



247. Example of Mounting Dry, or in Air. Prepare a shallow cell and dry 

 it ( 248). Select a clean cover-glass slightly larger than the cell. Pour upon the 

 cover a drop of 10% solution of salycilic acid in 95% alcohol. Let it dry spon- 

 taneously. Warm the slide till the cement ring or cell is somewhat sticky, then 

 warm the cover gently and put it on the cell, crystals down. Press on the cover 

 all around the edge ( 246); seal, label and catalog (\ 253, 308, 309). 



A preparation of mammalian red blood corpuscles may be satisfactorily made 

 by spreading a very thin layer of fresh blood on a cover with the end of a slide. 

 After it is dry, warm gently to remove the last traces of moisture and mount blood 

 side down, precisely as for the crystals. One can get the blood as directed for the 

 Micro-spectroscopic work (g 210). 



FIG. 137. Turn-Table for sealing cover-glasses and making shallow mount- 

 ing cells. ( Queen & Co.) 



| 248. Preparation of Mouuting Cells. (A) Thin Cells. These are most 

 conveniently made of some of the cements used in microscopy. Shellac is one of 

 the best and most generally applicable. To prepare a shellac cell place the slide 

 on a turn-table (Fig. 137) 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 that 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 spontaneously, 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 when the finger nail is applied to it. 



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

 sive 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. 



