Neutral fixer for field

William C. Banta WCBANTA at
Fri Jun 10 21:28:56 EST 1994

I've been working on the histology and development of marine
bryozoans for many years.  We are looking for a recipe for a fixer
that is practical for use in the field.  For many years I used
2-4% buffered formalin, but there is a great danger that delicate,
lightly calcified bryozoans will be partly decalcified if they
are not transferred to alcohol shortly after fixation.  Besides,
the state of fixation after formalin is not all that much better
than with just preservation in 70% alcohol.  Our favorite fixers
are things like cocodylate buffered glutaraldehyde and osmium-
based fixers, but obviously these are completetly impractical in
the field.  (It costs over $90 just to wrap a half gram of
osmium tetroxide for shipping!)  Has anyone out there experimented
with other fixers which are neutral or basic in pH?  Chloroform-
based fixers, for example?  Any suggestions?  If the agent overfixes
it is not useful in the field.  Colored materials are preferably
avoided.   We found picric acid useless in any combination.

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