158 MOSSES AND LIVERWORTS 



glass gives a better finish to a slide, yet the 

 square form is often really preferable, because it 

 allows much more mounting surface, and will thus 

 better accommodate the larger objects; though 

 the very fact of the glass being square makes it a 

 more difficult matter, both to centre it on the glass 

 slip, and also to clean it preparatory to sealing the 

 cell, as the corners are very apt to catch in the 

 handkerchief that is used to wipe off the super- 

 fluous mounting material, and in this way a 

 mount may very easily be spoiled. The most 

 useful sizes of cover-glass are in. and in., or 

 J in., while, if the specimen should be unusually 

 large, specially cut pieces -J in. by 2 in. should be 

 procured. Two or three cambric handkerchiefs 

 will be needed, both for washing and drying the 

 instruments after use, and for cleaning the glass 

 slips and cover-glasses, and one should be specially 

 set apart for this latter purpose alone, where 

 cleanliness is of such peculiar moment. 



Register of Slides, etc. Before proceeding to 

 deal more in detail with the subject of mounting 

 objects for the microscope, let me devote a few 

 words to the matter of the storing and registering 

 of specimens and slides, for it is by no means 

 unimportant to adopt some definite system from 

 the outset, on which to work. A cabinet for the 

 slides is, of course, a prime necessity, and it Vill 

 be a saving in the long-run to get one that will 

 hold a large number, for slides have a wonderful 



