He was at Wistar from 18 years .
In 1980 , he was named Wistar Professor of Genetics at the University of Pennsylvania and associate director of the Wistar Institute , titles he held until 1988 .
He was at Wistar Professor of Genetics from 18 years .
In 1980 , he was named Wistar Professor of Genetics at the University of Pennsylvania and associate director of the Wistar Institute , titles he held until 1988 .