slide restoration

[R. Zander]

Older microscopic mounts were made with a number of techniques, mountants and
sealants. It may be impossible to repair old slides. The big problem, I think,
it whether the slide was made with a glycerine-based mountant (as a
semipermanent mount of water-based fresh material) or with a resin with a
complicated technique of removing the water with an alcohol series. When my
slides dry out, I can revive them by heating them, lifting off the then
loosened coverslip with forceps, adding glycerine or glycerine jelly, and
replacing the slip: but then all my slides are water-based with gum chloral,
lactophenol, or glycerine jelly, or something of the sort. If the slides are
resin, this may not work, and you may have to heat, lift off the loosened
coverslip, add balam, replace coverslip. To tell the difference between resin
and water based mounts, you might run some toluene underneath the slide...
if it loosens and the slip and contents start to move around, then resin is the
best bet for remounting. Just a guess, however.

Two fine publications with info on a wide variety of older methods of mounting
microorganisms, and for repairing them, are:
Gatenby, J. B. & H. W. Beams. 1950. The Microtomist's Vade Mecum. 11th ed.
Blakiston, Philadelphia.
Gray, P. 1954. The Microtomist's Formulary and Guide. Blakiston Co., New York.

R. Zander


Birger Neuhaus wrote:

> Dear TAXACOMERS,
>
> reviewing my slide collection of "worms" up to 150 years old I realized
> that an increasing number of slides suffers from different problems:
>
> 1. The coverslips of slides some 50-100 years old have disconnected from
> the embedded whole mount. Is somebody aware what kind of embedding medium
> was used commonly at that time in Germany, Europe, or the USA? Is it
> possible to identify the embedding medium in one way or another easily?
> 2. The embedding medium (might be canada balsam) has withdrawn from around
> the specimen leaving the specimen in a cavity. Is there any possibility to
> re-embed specimens?
> 3. Slides from the rotifer collection of Charles Rousselet (slides made
> around 1910) show white precipitations in the periphery of the sealed
> coverslip. The embedding medium is glass-clear and not yellowish as in
> other material from that time.
> 4. Slides occasionally break apart, and we try to glue together major parts
> with a glass-clear 2-component epoxid resin (Henkel: Pattex Kraft-Mix).
> 5. Which embedding medium/procedure would you recommend for permanent
> slides of fresh specimens of a) Crustacea and b) "worms" such as Polychaeta
> or Nematoda? Sealed paraffin-glycerin mounts as commonly used for nematodes
> probably require regular inspection intervals o check the quality of the
> slides?
>
> I have looked through several books on the preservation of natural history
> collections, but did not find hints to how to solve problems as mentioned
> above. I would greatly appreciate your comments, suggestions, hints to
> published references, ...
>
> Birger
>
> ------------------------------------
> Dr. Birger Neuhaus
> Museum fuer Naturkunde
> Institut fuer Systematische Zoologie
> Invalidenstr. 43
> D-10115 Berlin
> Germany
> Tel.: +49 (0)30 2093 8525
> Fax: +49 (0)30 2093 8528
> e-mail: birger=neuhaus at museum.hu-berlin.de



--


Richard H. Zander, Curator of Botany
Patricia M. Eckel, Research Fellow in Botany
Buffalo Museum of Science
1020 Humboldt Pkwy, Buffalo, NY 14211 USA
bryo at paradox.net   voice: 716-896-5200 ext. 351