Later he had a private practice in Kassel, and travelled extensively throughout Europe, particularly Paris, where he collaborated with physicians that included Claude Bernard (1813–1873), Jean-Martin Charcot (1825–1893) and Jean Zuléma Amussat (1796–1856).
Jean-Paul Sartre | Jean-Jacques Rousseau | Jean Cocteau | Jean Genet | Jean-Luc Godard | Wyclef Jean | Jean Racine | Jean Chrétien | Jean Michel Jarre | Jean Paul Gaultier | Jean Nouvel | Jean-Michel Basquiat | Jean Giraud | Jean Sibelius | Jean-Luc Ponty | Jean-Baptiste-Camille Corot | Jean-Claude Van Damme | Jean Renoir | Jean-Pierre Rampal | Jean-Léon Gérôme | Jean Harlow | Jean Anouilh | Billie Jean King | Jean Giraudoux | Jean-Bertrand Aristide | Jean Baudrillard | Jean-Pierre Thiollet | Jean-Martin Charcot | Jean Gabin | Jean de Florette |
Other important names in its historical development were Jean Zuléma Amussat (1796–1856), Auguste Nélaton (1807–1873), Henry Thompson(1820–1904) and William Cheselden (1688–1752).