Complex sentence: He studied medicine at the University of Halle under physiologist Johann Christian Reil (1759--1813), and following graduation returned to Bielefeld as a general practitioner and later director of a hospital for the poor.
Split into simpler sentences: He studied medicine at the University of Halle under physiologist Johann Christian Reil (1759--1813). Following graduation returned to Bielefeld as a general practitioner, later serving as director of a hospital for the poor.