Imagine studying a pseudoscorpion, a tiny arachnid that is almost too small to see. In 1891, Harvard curator Nathan Banks mounted such a creature on a microscope slide. Over 130 years later, that same specimen is still carefully preserved in the Museum of Comparative Zoology (MCZ).
In trays, boxes, and drawers in the museum’s collections spaces, there are around 50,000 tiny treasures in the form of invertebrate specimens mounted on microscope slides, some more than 150 years old. Under magnification, these slides reveal fascinating anatomical details, such as the delicate veins of a dragonfly’s wing or the symmetry of a beetle antenna.
The slides are colorfully and ornately labeled and transport the viewer to a time when Harvard graduate Addison Emery Verrill etched on a slide featuring a Leptogorgia soft coral specimen, “sent to James Dwight Dana by Charles Darwin.” The slide is on display in the exhibit. Also on display is a slide made by William Morton Wheeler for his 1893 thesis study on insect embryos. This is paired with a microscope that Wheeler, who became a Harvard professor, used at the MCZ in the 1920s.
In the mid-19th century, microscopes offered scientists a means to study the details of invertebrates, opening up a world of scholarship. The MCZ’s incredible slide collection spans species and continents, decades and collectors. It’s still growing today as Harvard researchers continue to mount new specimens on slides.
In 2024, Mansi Srivastava, Professor of Organismic and Evolutionary Biology, Curator of Invertebrate Zoology in the Museum of Comparative Zoology, and Co-Chair of the Department of Organismic and Evolutionary Biology, joined with curatorial staff from across Harvard’s Entomology, Invertebrate Zoology, and Malacology collections to embark on a massive digitization project. The goal: to locate, restore, rehouse, and digitize these slides that had been largely overlooked for over a century.
The project includes securing high-quality images of some 3,000 slide-mounted type specimens: the examples on which scientific names and descriptions are based. When the project is complete, a treasure trove of digital data to be shared with researchers and the public online.
Through the new exhibit Making the Invisible Visible: Digitizing Invertebrates on Microscope Slides, visitors will discover how digitizing slide-mounted specimens brings information from the collections to the wider world, truly making the unseen seen! At an Interactive microscope station, visitors can zoom in to explore a series of slides and compare a before-and-after example to see how MCZ staff cleaned and preserved a slide.
In the gallery, a wall of oversized images highlights the beauty and diversity of the slide-mounted specimens found at the microscope. This smaller-scale exhibit will be on display in the Arthropods gallery, which also features the new Velvet Worms exhibit and the famous Rockefeller Beetles.
This exhibition was supported by a grant from the National Science Foundation to Mansi Srivastava, Naomi Pierce, Adam Baldinger, Crystal Maier, and Jennifer Trimble. High-resolution images were taken by Amelia Lawson, Even Dankowicz, and Jenni Nelson.
Making the Invisible Visible: Digitizing Invertebrates on Microscope Slides opened December 12 at the Harvard Museum of Natural History. For museum hours and visitor information, please visit hmsc.harvard.edu/visit.
