Johann was born in 1724 in Schinkau,
Bohemia (now
Žinkovy, Czech Republic). His father was manager of the estates of Count Wenzel von Zwrtby. Johann was educated at a
Jesuit seminary where he learned
Latin and
philosophy. He then studied medicine at the "Carolina Medicin". Between 1746 and 1750, he made trips to
Padua,
Montpellier,
Paris and several German universities and after his return published a
dissertation on the uses of electricity in medicine. In 1753, he was made associate professor of natural philosophy in
Prague and began to collect materials for a work on the natural history of Bohemia. Interrupted by the war and riots, he travelled to
Italy from 1757 to 1759, where he collected and described a number of new species of marine
invertebrates. On his return he was appointed professor of botany and pharmacology and in 1762 elected a
fellow of the Royal Society. On a natural history trip to Bohemia he contracted a severe chill. He died on 16 October 1768 in Prague. ==Writings==