‘Virtual microscope’ will zoom in on Peabody’s historic scientific slides

Closeup of a slide revealing intricate swirls and colors.
A screen shot of the Euborlasia nigrocinta slide specimen magnified using the zoom feature on the digital microscopy web tool under development. The tool will be unveiled in June.

Wesley R. Coe, professor of zoology at Yale during the early 20th century, devoted his career to studying ribbon worms — a group of mostly marine-dwelling creatures that includes more than 1,000 known species.

Identifying ribbon worms often requires examining their internal anatomy under a microscope. To that end, Coe created thousands of microscope slides of worm specimens over the course of his career. He was a deft hand at the job.

Coe’s slides are stunning,” said Daniel Drew, museum assistant II in the Peabody Museum of Natural History’s Division of Invertebrate Zoology, where the late zoologist’s handiwork is among about 52,000 microscope slides housed in the museum’s invertebrate zoology collection.

A digitization project underway at the Peabody Museum is developing a “virtual microscopy” web tool through which users can view and magnify high-resolution images of hundreds of scientifically or historically significant slides, including a selection of Coe’s, on their computer screens.  

'Invaluable' educational resource

This will be an invaluable educational and scientific resource,” said Eric Lazo-Wasem, senior collections manager in the Division of Invertebrate Zoology and the co-principal investigator and manager of the project. “We want to invite researchers into the collection and also provide teachers a dynamic way to incorporate these fascinating materials into lessons.”

As part of the project, which is funded by a National Science Foundation grant, the museum will make images and associated data of the entire slide collection available on its website. But the searchable web tool is the project’s centerpiece. It will allow users to browse through at least 3,000 slides and study them via two methods: One will enable them to zoom-in on slide specimens as though studying a streetscape on Google Maps. The other will allow them to bring entire images into sharp focus, revealing minute details, as though peering through a microscope — only better, according to Lazo-Wasem.

Image of a shrimp-like creature
Ptilohyale plumulosa, a tiny sea-dwelling crustacean, rendered in minute detail using the Peabody's scanning system. The Peabody is building a website to host a series of high-resolution images of specimens from its microscope slide collections.

When you’re looking at a slide under a microscope, you can only see one little area at a time,” he said. “Our tool allows you to see the entire slide in context. It’s a whole new level of information you can’t get through an eyepiece.”

Many slides are visually striking.

Drew, who is responsible for photographing the slides and compiling the associated data, presented a box of slides Coe had prepared of Euborlasia nigrocincta, a species of ribbon worm. Each slide contained dozens of razor-thin sections of a single worm stained and arranged in a grid. Viewed through the web tool’s zoom function, the specimens’ swirling colors resemble polished agate or an abstract painting.

Corals, parasites, sponges and more

The slides’ visual appeal is secondary to their scientific and historical value, said Drew.  

We have some of the richest historical collections anywhere in the world,” he noted.

Among the slides are fragments of soft coral specimens prepared by Coe’s mentor, Addison E. Verrill, Yale’s first professor of zoology. Verrill, who taught at the university from 1864 to 1907, is credited with describing and naming more 1,000 new species of animals, mostly marine invertebrates.

There are thousands of slides that belonged to Alexander Petrunkevitch, a renowned arachnologist who began teaching at Yale in 1910. Petrunkevitch amassed a large collection of parasites, including slides he prepared of original specimens studied by Theodor Bilharz, a German scientist who performed groundbreaking research on parasitic flatworms in the mid-19th century.

Those slides are very important to the history of the study of disease,” Lazo-Wasem said.

Slide of ovoid specimen with abstract swirls
A magnified cross-section of Euborlasia nigrocinta, a ribbon worm specimen. The slide specimen was prepared by Yale zoologist Wesley R. Coe, who joined Yale faculty in 1896.

A large collection of slides by the late Willard Hartman, professor of zoology and former director of the Peabody, inspired the digitization project, Lazo-Wasem said.

Hartman travelled the globe collecting sea sponges, amassing more than 10,000 specimens. There are slides associated with most of the specimens. A substantial portion of the collection has never been identified.

I figured we needed to put this information out there to draw researchers into the collection and entice them to work in it,” Lazo-Wasem said.  

He approached Leo Buss, former curator of invertebrate zoology and professor emeritus of ecology and evolutionary biology, and suggested digitizing Hartman’s slides. Buss, who is principal investigator of the project, suggested they digitize the museum’s entire slide collection, which was sitting in boxes not cataloged and unused.

'Surprising' discoveries

Drew has spent two years sifting through the massive collection, organizing and recording important data for each individual slide. The task required substantial detective work as most of the slides, apart from Hartman’s, were not linked to the specimens from which they were drawn. Label data was often incomplete, obsolete (scientific names can change over time), or in a foreign language (e.g., many of Pentrunkevitch’s slides are labeled in German).

Drew’s research has revealed that the collection is richer and more historically significant that previously understood, according to Lazo-Wasem. 

Dan is constantly surprising me with things he has discovered,” he said. 

Image of a pinwheel-shaped creature with eight arms
This slide specimen of a moon jellyfish larva was prepared by Alexander Pentrunkevitch, an arachnologist who began teaching at Yale in 1910.

Over the Peabody’s more than 150-year history, its researchers have identified thousands of new species. When Drew began exploring the collection, Lazo-Wasem assumed 500 slides would be of type specimens — the initial specimen used to describe and name a new species.  

We’re over 3,000 now,” Drew said.

Petrunkevitch’s parasite collection, which contained over 2,000 species and dated to the mid-19th century, was particularly challenging to work through and required mining old scientific literature, Drew said.

The division is using a microscope-based scanner, purchased through the NSF grant, to image the entire collection and create about 3,000 dynamic, high-res images to populate the web tool. About 10% of the collection’s 52,000 slides had crystallized and were no longer usable, Drew said. The deteriorated slides were prepared using synthetic mounting media as opposed to organic materials, such as balsam, a traditional substance once favored for its archival qualities.

The digital microscopy website is slated to launch in June 2018.  It will include a mapping feature identifying where specimens were collected. As a user zooms in on certain slides, annotations will appear to point out and identify specific structures in an organism.

For example, zooming in on a sample of muscle tissue produces several arrows pointing to Trichinella spiralis, tiny parasitic worms that cause trichinosis, embedded in the tissue.

Enhancing lesson plans 

Lazo-Wasem and Drew are consulting with high school teachers to determine how the website can best enhance their lesson plans.

Selected images will be packaged into study sets to help teachers develop lesson plans on themes such as “coral reef organisms,” “Long Island Sound micro-invertebrates,” and “parasites and the human body,” Lazo-Wasem said.

I’ve spoken with teachers who tell me they don’t do much with microscopes due to the expense of buying and maintaining them and obtaining slides,” Lazo-Wasem said. “When our website is live, they won’t need microscopes. All they’ll need to do is visit the website.”

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Media Contact

Mike Cummings: michael.cummings@yale.edu, 203-432-9548