Historical Markers
Caspar Wistar (1761-1818) Historical Marker
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Caspar Wistar (1761-1818)

Philadelphia and its Countryside/Lehigh Valley


Marker Location:
240 South 4th Street, Philadelphia

Dedication Date:
December 5, 2000

Behind the Marker

Head and shoulders formal painting of Caspar Wistar.
Caspar Wistar, by Thomas Sully, 1830.
To prepare for his journey, markerMeriwether Lewis consulted with two of the nation's top physician-scientists when he visited Philadelphia in the spring of 1803. The first, markerBenjamin Rush, was also one of the nation's most respected citizens and a close personal friend of Thomas Jefferson. Lewis also visited Caspar Wistar, a popular professor in the medical school at the University of Pennsylvania who was considered the nation's leading expert on human anatomy.

When Jefferson suggested that Lewis study with Wistar, he had more than Wistar's medical knowledge in mind; Jefferson wanted Wistar to give Lewis a crash course in paleontology, another of Wistar's specialties. The President believed that the Western Plains might still be populated with the giant mastodon, and he wanted Lewis to be prepared for an encounter. Indeed, he instructed Lewis to do his best to hunt down such a beast - or, better yet, to trap one alive.

Wistar was only fifteen years old when Jefferson and Rush signed the Declaration of Independence. As a member of the pacifist Religious Society of Friends, Wistar would not bear arms and fight in the war. Instead, at the age of sixteen, he served his country by tending the Americans wounded in October 1777 at the markerBattle of Germantown. From then on, Wistar wanted a career in medicine.

After apprenticing with Philadelphia physician John Redman, Wistar studied at the University of Pennsylvania, continued his education in England and Edinburgh, and then completed his medical degree in 1786. Hired by the University of Pennsylvania Medical School in 1787, Wistar taught chemistry, physiology, and anatomy. Realizing that students learned better when they could see what he was describing, Wistar introduced gigantic models to illustrate his anatomical lectures.

In the 1790s, Wistar met and worked with Jefferson through the American Philosophical Society. Together, they assisted Charles Willson Peale as he reassembled mastodon bones into skeletons for his museum on the second floor of Independence Hall. Wistar also studied the fossilized bones of a giant sloth called a "megalonyx," which Jefferson donated to the American Philosophical Society. His analysis, published in 1799, was the first study in vertebrate paleontology by any American.

Image of Mastodon bone
Image of Mastodon bone

In his home at Fourth and Locust streets, Wistar taught Lewis how to spot fossils, a lesson that proved useful when the Expedition neared Cincinnati, Ohio, and the exposed bluffs of the Missouri River. Taking a detour from the route, Lewis studied a huge deposit of petrified Mastodon remains that had recently been found at a place in Kentucky called Big Bone Lick. In his report back to Jefferson, Lewis noted a "tusk of immense size."

During the first winter encampment, in what is now North Dakota, Lewis encountered a similar site with fossilized mastodon bones near an Osage village. None of these fossils ever reached the East - the shipment from Big Bone Lick was lost on its way back down the Mississippi and the Osage Village specimens "were in an imperfect state." But the Expedition did collect, send back, and eventually return with a rich variety of fauna, which ranged from Bison skins to a live prairie dog.

Although Wistar maintained his passion for paleontology, he became better known for other achievements. In 1811, he published A System of Anatomy for the Use of Students of Medicine, the first American textbook on anatomy. In 1813 Wistar succeeded Rush as President of the Pennsylvania Society for Promoting the Abolition of Slavery. Two years later he followed Jefferson as the President of the American Philosophical Society. For many years Wistar's home was a gathering place for the city's cultural elite, who were charmed by their urbane and gracious host. After Wistar's death in 1818, the spirit of his soirees continued in the markerWistar Institute, founded in the 1890s by his great nephew. Wistar is immortal in another form, too, for the purple-flowering vine called "Wisteria" was named in his honor.
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