
i 
348 THE NORTHERN MICROSCOPIST. 


when freshly gathered ; and those who are wishful to add to their 
cabinet, as perfect a slide as possible, must pay some little atten- 
tion to the fruiting seasons of the various species, so as to place on 
the slide plants showing in addition to the leaf structure, the 
capsule with its peristome, and, wherever possible, the operculum ) 
and the calyptra. 
The best medium and the one generally used is glycerine jelly, 
as it preserves the natural colour of the moss, and is not of so 
highly refractive a nature as balsam; an important consideration in 
observing the cell structure of mosses, alge, &c., and, in fact, all 
vegetable structure where staining is not applicable. 
First of all centre your glass slip by means of the turn-table, 
with an ink ring about the size of the cover glass required; then 
having liquified your jelly, by placing the bottle in a cup of warm 
water, place a fair portion of the jelly on the slip, take your 
specimens fresh from the water and arrange them on it; put on the 
cover glass, using as easy a clip as possible, as the jelly is of an 
elastic nature and more liable to spring if too tight a clip has been 
used ; now hold your slide over the lamp, but not too close to the 
flame, until it boils, when if it is carefully watched a very percep- 
tible crack will be heard; at this moment the slide should be 
immediately withdrawn from the lamp and placed upon a cold 
surface, such as the window sill, when the jelly will rapidly con- 
tract and in the course of half an hour all air bubbles will have 
been excluded. Before placing outside, the lids and calyptras 
should be carefully put in position under the cover glass, with a 
very fine needle, as they are apt to find their way out during the 
boiling. 
It often happens that when the specimens are very thick, the 
slide after cooling will still contain a few air-bubbles ; In this case 
add a little more jelly to the slide, and repeat the process. 
I have found, however, in obstinate cases the following sugges- 
tion of Mr. Miles to prove very successful. 
Take your slide with the clip on and flood it with boiling water 
from the kettle until you have removed all the jelly and your 
Specimens are mounted solely in warm water, now tilt your slide a 
little and apply with a pipette the warm jelly to the upper edge of 
the cover-glass, when, if assisted a little with blotting paper at the 
lower edge, the jelly will gradually take the place of the water and 
you will have a mount quite free from air bubbles. With care, 
nearly all Mosses and Hepatics will stand the boiling process, 
although it is said by some to change the natural colour of the 
plant, but I think this is due either to over-boiling or to imperfect 
jelly, as the bulk of my specimens have all been boiled and are now 
as fresh in colour as the day they were mounted. For mounting 
without boiling, and this is necessary in the case of inflorescences, 

