176 MOSSES AND LIVERWORTS 



the melted jelly; and if its own weight is not 

 sufficient to cause the jelly to flow under the 

 whole of its lower surface, a little more can easily 

 be introduced. 



3. While the jelly in the cell is still liquid 

 a small additional quantity should be run all 

 round the outside edge of the cover-glass, in order 

 to allow for the subsequent shrinkage of the 

 gelatine ; this may seem a w r aste of good material, 

 as all this extra amount will have to be removed 

 before the cell is sealed, but the expenditure is 

 really well worth the making. 



4. As already mentioned, the superfluous jelly 

 should not be removed, and the cell sealed, for 

 at least two or three months after mounting. 



5. The cabinet containing the slide should stand 

 in a room with a fairly equable temperature, and 

 where it will not be exposed to draught. 



Glycerine. Where thin objects, such as moss 

 leaves, are to be mounted, requiring but a slight 

 film of the mounting medium, glycerine itself may 

 be used. A very small quantity, just enough 

 to lie under the cover-glass, should be put on 

 the glass slip ; in this the specimen (prepared as 

 before) is placed, and the cover-glass is lowered 

 onto the glycerine. Any superfluous glycerine 

 must be carefully removed with a slightly wet 

 camel's-hair brush, the whole success of the 

 mount depending upon the thoroughness with 

 which this operation is carried out. Lastly, the 



