[Nhcoll-l] Transferring a worm to new fixative

Thu Mar 26 11:44:16 EDT 2026

I'm thinking Bouin's and AFA are definitely possibilities, I think. Looks like the pH range for stock Bouins is 0.5-3.5 and the pH of stock AFA solution are around 3.0-4.6. So there's some overlap, but could rule out one or the other.

To Dirk's point about osmotic pressures, I do not think the specimen was swelling or shrinking appreciably. It honestly looked to me more like the way soft tissue specimens look when first fixed in high percentage ETOH -- it looked like the surface of the specimen was getting "fixed", and tissues which were previously supple and translucent were becoming opaque and less flexible.

Also, to Fabian's point, I was not (and do not condone) trying to identify preservatives by smell intentionally. After the initial jar opening when I realizing the fluid wasn't ethanol, my little transfer experiment happened in our hood.

I'll investigate further next week, but for now at least the specimen is staying in its original fluid!
Best,
Nate
--

[The Ohio State University]
Nathaniel F. Shoobs
Curator of Mollusks
College of Arts & Sciences Dept. of Evolution, Ecology, and Organismal Biology
Museum of Biological Diversity, 1315 Kinnear Rd, Columbus, OH 43212
614-688-1342 (Office)
mbd.osu.edu/collections/invertebrates<https://mbd.osu.edu/collections/invertebrates>

From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> on behalf of Hans-Joachim Händel <Joachim.Haendel at zns.uni-halle.de>
Date: Thursday, March 26, 2026 at 5:57 AM
To: nhcoll-l at mailman.yale.edu <nhcoll-l at mailman.yale.edu>, info at naturhistorische-konservierung.de <info at naturhistorische-konservierung.de>
Subject: Re: [Nhcoll-l] Transferring a worm to new fixative

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Dear all,

Oligochaeta are often preserved in a mixture of formalin and alcohol. The mixing ratio can vary (depending on the preparer’s personal experience or the advice of their teachers).
Typically, a mixture of 90% alcohol and 35% formalin is used in a ratio of 9:1.

If the ratio of the new solution does not match the original, osmotic differences arise, leading to the problem described here.

btw: Fabian is absolutely right. Although the old methods can largely be ruled out here, there is often something of an alchemy involved in the preservation of ‘worms’. Particularly with Oligochaeta, Schaudinn’s fixing mixture was often used (1 part sublimate solution / 1 part 95% alcohol).

Fritz Schaudinn first published the formula in 1895, and later published it frequently in various modifications. This toxic agent is still in use in microscopy today,

All the best,
Joachim

--
Joachim Haendel

Center of Natural Science Collections
of the Martin Luther University (ZNS)
- Zoological Collection -

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>>> Am 26.03.2026 um 07:34, Fabian Neisskenwirth <info at naturhistorische-konservierung.de> schrieb:

Dear all,

just as a safety advice. Please do not smell preservation fluids. This practice is very dangerous and unprofessional. There are many simple methods to test physical properties and if there is an aldehyde content in the fluid.

The density alone of the fluid can give already a lot of information.

All the best,

Am 25.03.26 um 22:38 schrieb William Poly:
Hi Nate,

AFA (alcohol, formalin, acetic acid) is another possible solution as it is used for worms, and the combination of odors could make it difficult to identify by smell.

Bill

On Wed, Mar 25, 2026 at 12:57 PM Shoobs, Nate <shoobs.1 at osu.edu<mailto:shoobs.1 at osu.edu>> wrote:
Hey all,
We have a display specimen of a Giant Australian earth worm (Megalascides) with no data in our collection. It's in nice condition, but the fluid it's preserved in is quite dark orange (presumeably colors leeched from the animal) and thus it makes the specimen hard to see and appreciate.

I want to transfer it to fresh fluid so it's easier to examine, but I can't figure out what it's preserved in. I initially thought it was in 10% formalin, but test-dipping a portion of the animal in a fresh jar of 10% formalin caused a pretty immediate visible reaction (skin started peeling). The preservative is definitely not ethanol. It has an acrid odor like formalin. I don't have Schiff's reagent on hand. The specimen was acquired in the mid 60s early 70s, so I think it rules out many of the more obscure Victorian fixatives.

Any suggestions on a protocol to safely transfer it to a fixative that is less opaque (fresh formalin or ethanol)? The primary purpose of the transfer is for display and teaching, as the specimen is uncatalogued and has no data other than the ID, so the only thing that matters in this case is making sure it's not ruined aesthetically. (And of course, making sure I can figure out what the old preservative is to safely dispose of it).

-Nate
-
Nathaniel F. Shoobs, Curator of Mollusks
College of Arts & Sciences Dept. of Evolution, Ecology, and Organismal Biology, The Ohio State University
Museum of Biological Diversity
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