52 On Mounting. 



cover glass if it has been measured, and anything of 

 note which may be seen at the time it is examined. 

 Exceptionally good sections should always have a pri- 

 vate mark to show that they are not to be given away 

 or exchanged. 



They should be kept in a cabinet where they may lie 

 flat. 



ON BKEAKING DOWN OLD PKEPAEATIONS. 



It is often necessary to break down an old prepara- 

 tion and remount it. The cover glass may be broken, 

 the staining faded, or the cover glass may be too thick, 

 and preparations should never be discarded for these 

 reasons, as it is quite easy to remount them. When a 

 specimen has been mounted in glycerine, it is an easy 

 matter to remove the cover glass, all that is necessary 

 being to cut round the cement with a sharp knife, lift 

 the cover glass carefully with a needle, and float off 

 the section in water ; if it is very delicate the cover 

 glass had better be removed under water. The section 

 can then be washed, to remove the glycerine, and re- 

 stained if required ; it will then be ready for mounting 

 in the usual manner. 



To break down a specimen mounted in Canada bal- 

 sam or Dammar varnish is more difficult, especially if 

 it has been mounted long enough to allow the balsam 

 or Dammar to become hard. It must be placed in a 

 bath of chloroform until it becomes soft enough to re- 

 move the cover glass, and this may be facilitated by 

 passing the slide over the flame of a spirit lamp so as 

 to heat it very slightly, but this requires care as the 

 section may be easily ruined. 



