born Jan. 7, 1745, Tøndern, Den.
died March 3, 1808, Kiel
Danish entomologist.
He studied at Uppsala University with Carolus Linnaeus and from 1775 taught not only natural history but also economics and finance at the University of Kiel. He advanced theories progressive for his time, particularly the view that new species and varieties could arise through hybridization and by environmental influence on anatomical structure and function. His taxonomic research was based on insect mouthparts rather than their wings.