Rows of jars filled with specimens from Charles Darwin’s historic voyage sit quietly in London’s Natural History Museum (NHM). For 200 years, these specimens have remained unopened, protecting their secrets. Now, scientists are using lasers to peek inside.
Darwin isn’t just famous for his voyages but also for shaping the theory of evolution through his observations of wildlife in the Galapagos Islands while aboard the HMS Beagle. These specimens—ranging from mammals to fish—offer a treasure trove of insights into our planet’s history.
Until recently, the liquids preserving these specimens were a mystery. Opening the jars could mean losing valuable information due to evaporation or contamination. Wren Montgomery, a researcher at NHM, highlights the importance of understanding how these specimens are cared for. “Knowing what preservation fluid is in each jar could change how we handle collections for years to come,” she explains.
Historically, various fluids have been used for preservation. Ethanol and methanol were standard, but in the late 19th century, formaldehyde gained popularity. Different scientists had unique recipes for preserving specimens. Some mixtures included aromatic spices or other compounds to enhance preservation.
A recent study adopting spatially offset Raman spectroscopy (SORS) has allowed researchers to analyze these jars without opening them. This technique measures how laser light interacts with materials, revealing their chemical makeup through a spectral fingerprint. Montgomery, Mosca, and their team successfully identified the preservation fluids in about 80% of the jars analyzed.
They discovered that mammals and reptiles were often treated with formalin and suspended in ethanol, while invertebrates were typically stored in formaldehyde or its buffered forms, sometimes mixed with glycerol. This knowledge is vital not just for understanding Darwin’s collection, but for preserving over 100 million similar specimens in museums worldwide.
As technology progresses, the ability to study and care for historical specimens without risking damage will have lasting impacts on both science and conservation. “This method allows us to safeguard these invaluable specimens without compromising their integrity,” Mosca states.
For a more in-depth exploration of this methodology, check out the study published in ACS Omega.
For additional insights into the importance of specimen preservation, you can refer to reports from the UK Research and Innovation and related studies.
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