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Glycerin Jelly as a Substitute for Hoyer's Solution Mountant |
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Glycerin Jelly as a Substitute for Hoyer's
Solution Mountant Problems
arise when microscope slides are made, as is commonly the case in bryology,
with Hoyer's Solution. The slides remain sticky too long and arrive through
the mail smeared. Also, some researchers may not have access to Hoyer's
Solution as a mounting medium because a main ingredient, chloral hydrate, is
a controlled substance. You
can make an acceptable mounting medium with glycerin jelly. Simply make the
jelly according to standard formulae or 1.
dissolve a packet of granulated gelatin (available
in grocery stores; about 7 grams per packet) in enough cold water to hydrate
it, stirring well, then heat to fully dissolve. 2.
add 50 to 100 ml of drugstore glycerin, stirring with
continued mild heating until mixed well. 3.
pour the hot solution into a flat dish. 4.
let harden overnight - and let the water portion
evaporate for a day or so preferably in a hot place like a herbarium drier. 5.
the nearly pure gelatin and glycerin mixture is now
scored into long "worms" and removed from the plate. The
glycerin jelly will be hard to remove from the plate unless the water portion
has evaporated. It is best to evaporate the water portion with heat since glycerin
absorbs water, to some extent, from the air. Method A: Put your plant material on a slide in water,
soak, add pure glycerin and heat with a cigarette lighter so the water
evaporates somewhat and the plant material plumps up with glycerin after an initial
collapse. Make sections, etc. Take a strip of glycerin jelly and pinch
off a portion, put on the slide with the glycerin-heated material and heat
some more being careful to apply the heat rather generally rather than in
only one spot (which can crack the slide). Arrange material and gently add a
cover slip. It hardens in a minute and may be mailed when cool - which is
almost immediately after labeling. Don't worry about the clearing aspect of
Hoyer's solution, material usually doesn't have to be cleared to be studied
or illustrated, or if you must clear it, dip the most plant in lactic acid
for a minute or so (or heat in the pure acid) before preparing the glycerin
jelly mount. Method B: I have a small hot plate near my
microscope. I set a microscope slide with the wetted plant (or sectioned
material) in a little water (or a mixture of water and a little glycerin) and
a cube of glycerin jelly on the hot plate. After a moment or two, the
glycerin jelly melts and some of the extra water evaporates. I remove the
slide, arrange the material and put a cover slip on it. The hot plate is one
of those coffee warmers you can pick up in a flea market for a buck or two.
This eliminated heating a cube of glycerin jelly on a slide, which can break
the slide if not it is heated evenly with the cigarette lighter. The hot
plate warms up whenever the microscope light is switched on. Note: Although you can put a dropper bottle of
glycerin jelly on the hot plate, the heat eventually turns the jelly brown,
and the gelatin breaks down so that it will not harden. Another note: Glycerin dissolves (eventually)
calcium carbonate. Also, if you make the glycerin jelly with a high
concentration of gelatin, then if you work on your specimen in a
water/glycerin mixture (which slows sections from flying around when you make
them] then any added glycerin jelly will not be too dilute (when mixed with
the pure glycerin on the slide] to harden. See also: Zander, R. H. 1997. On mounting delicate bryophytes in glycerol. Bryologist 100: 380–382. [Another note: Try this formula: Take 2 packets (2 time 7 g) of gelatine, Mix in 150 ml cold water to hydrate, Leave for about 30 min, Heat but don't boil for an hour or so until the liquid is clear, Swirl it to dissolve all gelatine, Add 200 ml glycerin, Heat for about an hour until dissolves and the liquid is clear, Pour on a clean metal baking pan to make a thin layer, Leave uncovered overnight or a couple days to allow water to evaporate, Slice into thin strips, Peel off and keep in a plastic box, Pinch off a small piece when wanted.] [Another note, this time to Bryonet Nov. 9, 2009: Technique with Mniaceae and other large-celled bryophytes:
strip leaves in water or Pohlstoffe solution or 2%
KOH, then add 2 tiny drops of pure glycerin to the water or solution mount.
Do cross sections and arrange leaves nicely in the unmixed water/glycerine mount, add a fingernail sized clod of glycerin jelley, heat with one of those butane lighters with the
nice torch flame taking care to heat the slide fairly evenly so it does not
break, heating until the glycerin jelly just melts or before it is completely
melted, rearrange the leaves and whatever else is on the slide, plop on a
cover slip, and after it cools it is solid and ready to mail or bang around
the lab without drying. Don't use 2% KOH with liverworts as the leaf cell
walls are attacked. Mounting in water and glycerin first, then heating plumps up the leaf cells with glycerin, then add the glycerine jelly. The slides are permanent if you keep them in a sealed cabinet with a small dish of glycerin to saturate the air with glycerin.] |
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