172 MOSSES AND LIVERWORTS 



will sooner or later chip off. A bath of a very 

 dilute solution of hydrochloric acid, which is just 

 slightly acid to the taste, is used by some for 

 completing the cleansing process, but I find that 

 nothing serves better than a cambric handkerchief 

 moistened at the tongue. In sealing the cells, 

 care must be taken not to get the varnish too 

 liquid, as it is then very apt to run too far over 

 the cover-glass ; and when this happens, the only 

 way is to clean it off with turpentine, and after a 

 time to reseal. For closing round cells a turn- 

 table is, of course, a necessity. 



Nothing now remains but to affix the label, and 

 the slide is complete. Before, however, quite 

 leaving the subject of mounting, I propose to add 

 a few observations on the various media used, and 

 cannot do better than begin with 



Glycerine Jelly. The one drawback to this is 

 that it sometimes, and too often from some un- 

 known cause, develops a tendency to liquefy, and 

 this even after the slide has been finished for 

 several years. It is rather a bitter experience, on 

 going to a favourite mount, to find that tiny beads 

 of glycerine have forced their way through the 

 varnish all round the edge of the cover-glass, and 

 that the jelly surrounding the object is becoming 

 fluid. Some years ago I had the misfortune to 

 lose a considerable part of my then small col- 

 lection of slides in this manner, and since that 

 time have kept a careful record of all my mounts, 



