 In 1898, he became Professor of Botany at the University of Basel and the same year joined the German Valdivia-Expedition.This was a deep-sea expedition aboard the SS "Valdivia" led by Professor Carl Chun.The trip lasted 9 months, during which they visited the Canary Islands, Cameroon, Cape Town, (where he joined Rudolf Marloth on collecting trips in the southern Cape), Kerguelen, New Amsterdam and Cocos Islands, Sumatra, the Maldives, Ceylon, the Seychelles and the Red Sea.