194 Modern Microscopy 



shellac cement, and when this has dried, rub 9, way any 

 water-marks that may be left on the slide with a soft cloth, 

 and add another coat of cement. 



Wing-cases, legs, heads, and feet of diamond beetles 

 should be mounted in opaque cells in Canada balsam. 

 Take a slide, and with a turn-table run on a disc of black 

 varnish of the required size ; allow this to dry thoroughly. 

 Take a piece of black gummed paper and punch out a disc 

 of the same size as that on the slide to which it is to be 

 fastened. Now take a tin cell of the required depth — on 

 no account use brass or vulcanite cells ; they are affected 

 by the balsam, and the mount will be spoiled — lay the cell 

 on a slide, and apply a coat of cement to its upper surface : 

 allow this to become nearly dry, then take up the cell in a 

 pair of forceps, and bring its cemented surface in contact 

 with the paper disc on the slide, and with the point of the 

 forceps press the cell down until the cement adheres to the 

 paper. Now put away to dry in some place protected from 

 dust. Take the specimen to be mounted, examine it under 

 a microscope, and if dirty, v^^ash in some benzole, and then 

 let it dry again. Now place a small quantity of gum-water 

 in the centre of the cell, and put the specimen into it in 

 the desired position ; make sure that it adheres securely to 

 the gum, and put the slide away again until everything is 

 quite dry. Put the slide in a turn-table, and run on a coat 

 of shellac cement to its upper surface, and allow it to be- 

 come nearly dry ; then fill up the cell with Canada balsam, 

 clean, and apply a cover, which must be well pressed into 

 the cement until it adheres firmly ; put away for an hour, 

 and then wash away the exuded balsam with a soft brash 

 and some turpentine ; dry the slide with a soft rag, and 

 apply a coat of black shellac cement. 



Heads of flies having coloured compound eyes, such as 

 Tabanus, lace-wing flies, etc., should be mounted in opaque 

 cells in glycerine. Make the cell in exactly the same way 

 as directed for balsam mounts, but take care that the cell 

 is only just deep enough to take the specimen, as the 



