[Nhcoll-l] Speculation on color retention and color loss in preserved herps?

[Claire Smith]

Dear Kelly,

It may be possible that your garter snake was preserved in a 1% solution of propylene phenoxetol at some point in its history. From my current research it appears that propylene phenoxetol is good at preserving melanin, and also retains a degree of softness in specimens in the long term - even after they have been moved into other preservation fluids. We have specimens of a similar age (although not herps) that were preserved in this way which have retained a degree of flexibility.

Best wishes,
Claire

*******
Claire Smith (she/her), AFHEA
PhD Candidate: Colour retention in fluid-preserved museum specimens
Graduate Teaching Assistant, Cole Museum of Zoology (Wednesdays)
c.e.smith at pgr.reading.ac.uk<mailto:c.e.smith at pgr.reading.ac.uk>
claire.smith at reading.ac.uk<mailto:claire.smith at reading.ac.uk>
www.twitter.com/wetconservatrix<http://www.twitter.com/wetconservatrix>

From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Cassidy, Kelly Michela
Sent: Monday, November 6, 2023 8:04 PM
To: nhcoll-l at mailman.yale.edu
Subject: [Nhcoll-l] Speculation on color retention and color loss in preserved herps?

Curious about herp preservation techniques that affect color retention and loss.

We have a garter snake that was once used as a display and/or teaching specimens. It was in a straight glass tube, sealed at the ends with a black tarry substance. About 10 or 15 years ago, I removed the snake from its glass tube because the fluid and glass had become too discolored for it to be a suitable display specimen.  I rinsed it and transferred it to a jar in 70% ethanol, but I am not sure what the fluid in the original tube was. The snake was collected in 1938. For a specimen approaching 90 years old, its color pattern was unusually sharp, but it is also much more flaccid than a typical snake fixed in formalin and preserved in ethanol. (Picture attached.) Any idea what fixative or storage chemicals might have caused better color retention but might have been less good at preservation, leading to more flaccidness?


On the other end of spectrum, we have a number of specimens, most from the mid-20th century (1950s to 1970s) that are now almost entirely bleached of color. These nearly white specimens came to Conner Museum as part of an "orphaned" collection (from Walla Walla College). Not all of the specimens from Walla Walla are bleached out. I am guessing there was a period when their fixative or storage solution contained or lacked something that caused unusual bleaching. We have no records from the collection about fixative or storage methods. What is the most likely cause of such extreme bleaching? Lack of buffering or chemicals used for buffering?  Storage in denatured ethanol?


Dr. Kelly M. Cassidy, Curator, Conner Museum
School of Biological Sciences
Box 644236
Washington State University
Pullman, WA 99164-4236
509-335-3515

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