1863 apprenticeship as a bank clerk in Bonn; 1864-1868 studies of medicine at the University of Bonn; 1866 assistant to Schultze; 1867 employment as Unterarzt to Ruehle at the medical clinic in Bonn; 1868 doctorate from the University of Bonn with a dissertation entitled Beiträge zur Physiologie des Blutes; December 1868 state examination; 1868-1869 private practice in Oberpleiss; 1869 seven months of research work in Berlin where he visited the clinics and attended the lectures of Frerichs, von Graefe, Virchow, Westphal and Traube; 1870 assistant to Pflüger at the Physiological Institute in Bonn; 1873 assistant teacher of physiology at the agricultural academy in Poppelsdorf; 1874 associate professor of physiology and prosector in anatomy at the University of Bonn; 1881 resignation from his medical profession, move to Berlin, where he was appointed a professor at the newly founded Tierphysiologische Institut der Königlich Landwirtschaftlichen Hochschule; work with Geppert and experiments with Loewy and Lazarus; 1895 first Monte Rosa expedition with Schumburg; 1901 six weeks expedition to the Monte Rosa with Müller, Loewy and Caspari; 1903 three weeks expedition to the Monte Rosa with Durig; 1904 Geheimer Regierungsrat; 1906-1908 rector of the Königlich Landwirtschaftliche Hochschule Berlin; 1908 research trip to the USA; 1910 expedition to Tenerife with Pannwitz, Durig and v. Schroetter; 1919 retirement; honorary doctorates from the University of Vienna (1913), from the Tierärztliche Hochschule Hannover (1918) and from the University of Bonn.