34 



MICROSCOPICAL RESEARCH 



The slip must be placed on the turntable, and a ring of brown 

 cement run round the cavity (Fig. 20, B, 5-6) ; this must be allowed to 

 set hard, then another layer of the cement should be applied on the top, 

 into which the tin ring must be imbedded, and another cement ring to 

 seal it completely to the first. This must be allowed to dry thoroughly, 

 and, if necessary, the process repeated until the cell is built up to the 

 required height, so that the specimen can be enclosed without having to 

 use pressure upon it. A light "tacky" ring of brown cement should now 



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— 1 



o o o :• iOi 



A. 



Fig. 20. — A. Rings for building up cells. A". Cardboard rings made out of old post cards, 

 used for dry mounting. B". Tin rings for balsam or fluid mounts, i. Upper 

 side of caps for same. 2. Underside of caps showing the flange. B, 1-6. Cells 

 at various stages of construction. 4. With black background for opaque 

 mount. 5 and 6. Cells surrounding a cavity to give depth. 



be applied to the top of the cell, the cell filled with the mounting fluid, 

 and the specimen arranged, in position, (care being taken that the fluid 

 stands slightly above the margin of the cell), the cover slip must now be 

 applied to the left margin of the cell and gently lowered into position, at 

 the same time flushing out the superfluous fluid. Now place the mount 

 on the turntable, which is set in motion, and a little pressure applied to 



