200 Years. 200 Stories. Story 151: “Invertebrates of Glass ”

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three glass slugs crafted by Leopold and Rudolf Blaschka
Three of the glass invertebrates crafted by Leopold and Rudolf Blaschka. The leopard slug, Limax maximus (left), is a land slug that was native to Europe but is now an invasive species in the United States. Melibe australis (center) is a nudibranch or marine slug that lives in the waters off Australia. Elysia grandis (right), another marine slug, is from the South Pacific. These glass slugs are not shown to scale. The leopard slug is about 6 inches long, while the two marine slugs are about 2 inches long. All three labels note that the glass invertebrates were donated by Anna T. Jeanes.

Invertebrates of Glass

Invertebrate animals such as slugs are notoriously difficult to preserve as specimens. In formaldehyde or alcohol they shrink and lose their colors, and if allowed to dry out they become little more than raisins.

In the 19th century, Ward’s Natural Science Establishment of Rochester, New York, offered a full line of exquisite models of living invertebrates made by hand from glass. These were the work of Leopold Blaschka (1822–1895) and his son Rudolf (1857–1939), who honed their extraordinary talents through the thousands of glass models they created, many by exclusive contract to Harvard University. Though best known for their reproductions of orchids and other flowers, the Blaschkas also produced highly accurate models of jellyfish and planktonic organisms, together with the sea slugs and land slugs seen here. At their workshop in Dresden, Germany, the father-and-son team created their own techniques for forming and coloring the glass, which they shaped in the flame of a spirit lamp before gluing on separately formed detail parts and finishing with paint.

The specimens in the Academy’s glass invertebrate collection were mostly purchased from Ward’s in the 1870s by George W. Tryon, the first chairman of the Department of Malacology, and Anna T. Jeanes, a well-known Philadelphia socialite and philanthropist. They remain as beautiful and lifelike as the day they were made, more than 125 years ago.

Read about one particularly notorious invertebrate.

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